reﬂections - semantic scholar · the thoracic or cervical region, to prevent the oily contrast...

Norman E. Leeds, MDStephen A. Kieffer, MD

Index terms:Brain, CT, 10.1211Brain, MR, 10.1214Cerebral angiography, 10.124Myelography, 30.122Radiology and radiologists, historyReflectionsSpinal cord, MR, 30.1214

Radiology 2000; 217:309–318

1 From the Department of DiagnosticRadiology, University of Texas M.D.Anderson Cancer Center, 1515 Hol-combe Blvd, Box 57, Houston, TX77030 (N.E.L.), and the Department ofRadiology, State University of New York,Upstate Medical Center, Syracuse, NY(S.K.). Received December 8, 1999; re-vision requested January 4, 2000; revi-sion received April 5; accepted April 21.Address correspondence to N.E.L.(e-mail: [email protected]).© RSNA, 2000

Evolution of DiagnosticNeuroradiology from 1904to 19991

Neuroradiology began in the early 1900s soon after Roentgen discovered x rays,with the use of skull radiographs to evaluate brain tumors. This was followed by thedevelopment of ventriculography in 1918, pneumoencephalography in 1919, andarteriography in 1927. In the beginning, air studies were the primary modality, butthis technique was supplanted by angiography in the 1950s and 1960s. The firstfull-time neuroradiologist in the United States was Cornelius G. Dyke at the NewYork Neurological Institute in 1930. Neuroradiology took a firm hold as a specialtyin the early 1960s when Dr Juan M. Taveras brought together fourteen neuroradi-ologists from the United States and Canada to establish the nucleus of what was tobecome the American Society of Neuroradiology, or ASNR. This society’s initial goalswere to perform research and to advance knowledge within the specialty. Neuro-radiologists initially were able to diagnose vascular disease, infections, tumors,trauma, and alterations in cerebrospinal fluid flow, because the brain structure wasinvisible. Neuroradiology was forever changed with computed tomography (CT)because the brain structure became visible. Soon thereafter, magnetic resonance(MR) imaging was developed, and it not only provided anatomic but also madepossible vascular and physiologic functional imaging.

Imaging of the central nervous system began with radiographs (plain roentgenograms) ofthe skull, following the discovery of x rays by Roentgen in 1895. In the early 1900s, DrGeorge Pfahler (1) in the United States (Fig 1) and Dr Arthur Schuller (2) in Europe usedemulsion-coated glass plates to obtain images to diagnose cerebral tumors and otherlesions. The first major innovation occurred in 1918 with the introduction of ventricu-lography by Dr Walter Dandy (3), a prominent neurosurgeon at Johns Hopkins Hospital.Following this, in 1919 he reported on the first use of pneumoencephalography (4).

In 1927, Egas Moniz, a Portuguese neurologist, introduced opacification of the carotidartery with contrast medium by using a solution of sodium iodide. This technique becamefully developed in the 1930s with the advent of direct percutaneous puncture and iodin-ated organic contrast medium (Fig 2) (5).

The first full-time neuroradiologist in the United States was Dr Cornelius G. Dyke, whoassumed this position at the Neurological Institute of Columbia Presbyterian MedicalCenter in New York in 1930. He remained in this position until his untimely death ofleukemia in 1943, but during that time he published numerous pioneering articles and aclassic monograph in collaboration with Dr Leo M. Davidoff, the prominent neurosur-geon, in 1937—The Normal Encephalogram (6).

In 1952, Dr Juan M. Taveras (Fig 3) became head of neuroradiology at the NeurologicalInstitute of the Columbia Presbyterian Medical Center in New York, and from thesebeginnings, the envelope of neuroradiology was expanded and the future cadre of neuro-radiologists had its beginning. Dr Taveras became the father of neuroradiology by leadingthe charge for recognition of neuroradiology as a specialty; he was primarily responsiblefor the formation of the American Society of Neuroradiology. Dr Taveras recognized theneed for an organized group to represent American neuroradiology to promote the ad-vance of research and knowledge in this field. At a historic dinner meeting at Keen’s ChopHouse in New York City held on April 19, 1962, he brought together a group of 14neuroradiologists from the United States and Canada (Table). It was this invited group

Reflections

309

who, by responding positively to Dr Tav-eras’ recommendation, became foundingmembers of the American Society of Neu-roradiology.

Juan Taveras together with M. M. Schech-ter was further responsible for the recog-nition of the importance of our specialtyby both neurologists and neurosurgeonsin the United States through their manyscientific presentations and service onjoint committees with their clinical col-leagues. In addition, Dr Taveras developedthe first National Institutes of Health–sponsored fellowship training programin neuroradiology at the NeurologicalInstitute in 1960. Soon thereafter, DrSchechter developed the second fellow-ship program at the Albert Einstein Col-lege of Medicine in New York City. Thesetwo remarkably able and energetic indi-viduals were the two major forces in thedevelopment and recognition of the spe-cialty.

An advantage of choosing neuroradiol-ogy to practice at that time was that itseemed almost like general practice of ra-diology, since the daily schedule in-cluded interpreting conventional radio-graphs of the skull, sinuses, and spine, aswell as performing interventional proce-dures such as myelography, encephalog-raphy, and cerebral angiography. Skullradiographs in 1960 were read to identifypineal shift, sellar enlargement due to tu-mor, or erosion from elevated intracra-nial pressure, as well as to detect abnor-mal calcifications, bone erosion, or bonedestruction; metastatic lesions; and hy-perostosis of the calvaria. Spine radio-graphs were evaluated for degenerativevertebral changes, disk space narrowing,erosion of the vertebral end plates, bonedestruction or production, a fracture, lossof a pedicle, interpediculate widening,vertebral body scalloping, and scoliosisor kyphosis.

Myelography was performed with io-phendylate (Pantopaque), an oily ra-diopaque contrast medium that had tobe removed from the subarachnoid spacefollowing the examination, since residualPantopaque could lead to the develop-ment of arachnoiditis. During myelogra-phy, the patient’s head needed to be fullyextended, not flexed, when the patientwas tilted head downward to examinethe thoracic or cervical region, to preventthe oily contrast medium from spillinginto the cranial cavity.

Myelography was used to evaluate diskdisease (7) and extradural, intradural ex-tramedullary, and/or intramedullary le-sions or to identify a block to cerebrospi-nal fluid flow by an intraspinal lesion (8).

In this procedure, fluoroscopic and radio-graphic imaging were performed withthe patient lying prone on a 90°-to-90°tilting table. Images were obtained in theposteroanterior, oblique, and cross-tablelateral projections for accurate localiza-tion. In the upper thoracic or lower cer-vical regions, a spurious or transientblock might be encountered when thepatient was tilted head downward be-cause of the presence of hypertrophicposterior vertebral marginal spurs or in-folded ligamenta flava, which, with the

neck hyperextended, would compromisean already tight thecal sac. If the appar-ent block still persisted, when the patientwas returned to the horizontal position,turning the patient’s spine obliquelysometimes succeeded in relieving the ob-struction to the flow of the bolus of con-trast medium.

Pneumoencephalography was per-formed by successively injecting smallvolumes of air via lumbar puncture andthen removing small volumes of cerebro-spinal fluid with the patient sitting up-

Founding Members of the American Society of Neuroradiology

Norman E. Chase, MD Giovanni Di Chiro, MD*William N. Hanafee, MD Fred J. Hodges III, MDColin B. Holman, MD Norman E. Leeds, MDEugene V. Leslie, MD Donald L. McRae, MD*Thomas H. Newton, MD Harold O. Peterson, MD*D. Gordon Potts, MD Mannie M. Schechter, MD*Juan M. Taveras, MD Ernest H. Wood, MD*

* Deceased.

Figure 1. (a) Photograph shows the firstpublication of skull radiographs in diag-nosing tumor or infarct in Transactions ofthe American Rontgen Ray Society in 1904.(b, c) Lateral skull radiographs reveal opac-ity, outlined by arrows, considered to be tu-mor, which is probably hair with grease ortangles, as considered by H. B. Baker, Jr, aprominent neuroradiologist of the MayoClinic. (Reprinted, with permission, from theAmerican Roentgen Ray Society.)

310 z Radiology z November 2000 Leeds and Kieffer

right and the head flexed (Fig 4). Pneu-moencephalography was used primarilyto determine the presence and extent ofposterior fossa or cerebellopontine angletumors, pituitary tumors, and intraven-tricular masses (9). It was also used to ruleout the presence of lesions affecting thecerebrospinal fluid spaces in patients withpossible communicating hydrocephalus ordementia (Fig 5) (10). After the injection

of a sufficient quantity of air, the patientwas rotated, somersaulted, or placed in adecubitus position to depict the entire ven-tricular system and subarachnoid spaces.These patients were often uncomfortable,developed severe headaches, and becamenauseated or vomited.

At the Neurological Institute, a somer-saulting chair was developed by Dr Gor-don Potts in 1965 (11), so that manualrotation was no longer required and bet-ter filling of ventricles could be attained.Other somersaulting apparatuses for pneu-moencephalography were developed byDr Kurt Amplatz at the University ofMinnesota and by Elema-Schonander(the Mimer chair) in Sweden. Use of thisuncomfortable procedure was abruptlyterminated in the early 1970s when CTbecame available, because CT could de-pict the ventricular system and intracra-nial subarachnoid spaces directly with-out the need to introduce air into thesubarachnoid spaces. Pneumoencephalog-raphy was rarely used in the assessmentof supratentorial tumors.

If an obstruction of the ventricular sys-tem was known or suspected or if theintracranial pressure was elevated, ven-triculography was used for localizing anddefining the extent of supratentorial,third ventricular, or posterior fossa le-sions (12). For this technique, a catheterwas inserted into the lateral ventricles viaa burr hole or through a patent anteriorfontanelle, and air was injected. Ventricu-lography gradually disappeared from useas interpretation of angiograms im-

proved, and particularly when vertebralangiography became easier and safer toperform by using the catheter techniquevia the femoral artery.

Cerebral angiography in the early1960s was typically performed by meansof direct puncture of the common ca-rotid artery, the vertebral artery, or thebrachial artery (with retrograde injec-tion) (13,14). In the late 1960s and early1970s, cerebral angiography was per-formed predominantly by means of se-lective catheter angiography followingpuncture of the femoral artery. Cerebralangiography was first performed bymeans of a direct stick into the commoncarotid artery. Once the puncture wasmade, the needle was advanced with theuse of direct visualization, with the nee-dle antegradely within the arterial lumento make its position more stable. A flexi-ble plastic tube was connected to the nee-dle threaded with a two-way stopcock.This took pressure off the needle so it wasstabilized within the arterial lumen.

The common carotid artery in the neckwas first imaged by means of manual in-jection of a small aliquot of iodinatedionic contrast medium to be certain theneedle was well positioned in the arteriallumen and to avoid a subintimal or wallinjection. Serial angiography was thenperformed to evaluate intracranial ves-sels.

Images were obtained on a manual-pull or a power-driven (Sanchez Perez)film changer. Three or four film hard cop-ies were obtained, and separate injections

Figure 2. Lateral common carotid arteriograms obtained during the early phase. (a) Image reveals anterior cerebral arteries (A) with an earlyvascular stain (S) and an early draining vein (V), which indicates glioblastoma multiforme. (b) Image demonstrates a prominent middle meningealartery (arrows) inducing an early vascular stain (S) in a meningioma. (Reprinted from reference 5.)

Figure 3. Photograph shows Dr Juan Tav-eras, then head of Neuroradiology at the Neu-rological Institute of the Columbia Presbyte-rian Hospital, in his office at the NeurologicalInstitute in New York in 1962. (Image courtesyof Juan M. Taveras, MD, Department of Radi-ology, Massachusetts General Hospital, Bos-ton.)

Volume 217 z Number 2 Evolution of Diagnostic Neuroradiology z 311

were required for each plane. In the1960s, a serial roll film changer was usedat the Neurological Institute to enablethe acquisition of as many images as re-quired, usually two per second for 3 sec-onds and then one per second for 6 sec-onds.

The lesions we looked for included vas-cular lesions, such as aneurysms, arterio-venous malformations, arterial or venousocclusions, and vasculopathies (abnor-malities of the blood vessel wall); cerebraltumors; traumatic lesions such as sub-dural or epidural hematomas; cerebralcontusions; intracerebral hematomas; andtraumatic fistulas or aneurysms. A lesionwas revealed by the midline shift of ar-teries or veins and by the localized dis-placement of arteries or veins. The syl-vian triangle, demarcated on the lateralprojection image by the middle cerebralartery and its branches, aided in tumorlocalization. Midline shift of the anteriorcerebral artery occurred with frontal, pa-rietal, or temporal masses, whereas deeplesions involving the thalamus or medialtemporal region resulted in shift of theinternal cerebral vein. Shifts of the ante-rior cerebral artery were characterized asrounded (anterior frontal mass), angled(temporal or deep frontal mass), or square(posterior frontal or parietal lesion) (15).

The various gliomas could be identifiedby relating vascular patterns to circula-tory changes in the different phases (ar-terial, intermediate, or venous) of the an-giogram. In glioblastoma multiforme, forexample, a tumor circulation with sinu-soidal channels and a typical contrast en-hancement pattern appeared early in thearterial phase and disappeared before thenormal veins appeared (Figs 2a, 6) (16).Early opacification of venous drainagefrom the tumor was a frequent finding(Figs 2a, 6). Most other gliomas of a lessergrade manifested as a lesion with little orno abnormal vascularity.

Meningiomas produced a characteris-tic well-defined blush, with blood supplycoming from the internal and externalcarotid arteries (Fig 2b). The diffuse en-hancement pattern was sharply demar-cated, appeared early, and remained lateuntil after the veins had emptied. Meta-static lesions could be very vascular orhypovascular. Vascular lesions appearedas an intense blush and/or collection ofabnormal vessels that developed in thelate arterial, intermediate, or early or latevenous phase.

The abnormal vascular patterns werecategorized and used to distinguish thevarious types of hypervascular lesions. Inaddition to vascular displacements, vari-

ations in vascular dynamics also proveduseful. These included delayed filling ofveins, as well as early filling of veins anddelayed filling of arteries (17). All thesechanges in vascular dynamics were usedas the basis for today’s perfusion imag-ing.

Circulation time was measured accord-ing to the method of Torgny Greitz, MD,in Stockholm (18) and was influenced byvascular lesions, tumors, aging, and in-creased intracranial pressure. The normalcirculation time, as measured by Greitz(18), was approximately 4.13 seconds.Subsequently, Leeds and Taveras (17,19)not only measured circulation time to be4.3 seconds by using the method of Gre-itz (18), they also measured local circula-tory dynamics in arterial, intermediate(capillary), and venous phases and iden-tified the variable influences of aging onlocal circulatory dynamics, from the pe-diatric to the elderly patient.

A vascular blush or enhancement pat-tern might also be observed in the pa-tient with ischemic changes (Fig 7). Thisis the result of luxury perfusion andchanges in cerebral autoregulation (20).To elaborate further, as a result of loss ofcerebral autoregulation, the capillary bedis opened, and the dilution that normallyaffects the hypertonic contrast mediumis lost. The contrast medium within thecapillary bed and draining vein is there-fore as bright as it is during the arterialphase (Fig 7b). In the patient with nor-mal cerebral autoregulation, the hyper-tonic contrast medium within the capil-laries becomes diluted, such that theintensity of the contrast medium is re-duced in the veins as compared with thatin the arteries (20).

Direct puncture of the vertebral artery,a technique pioneered by Phillip Sheldon(21) in Oxford, England, could be per-formed but was difficult to do, since theneedle could not be threaded into theartery. The vertebral artery and aorticarch could also be examined by means ofpuncturing the right brachial artery andthreading the needle retrogradely upthe artery (13,14). This became feasibleonce power injectors were developed thatcould deliver the bolus of contrast me-dium retrogradely into the subclavianartery and brachiocephalic trunk. Theright brachial arterial injection couldbe used to examine the aortic arch onthe right side, as well as the brachio-cephalic trunk, and to depict the rightcommon carotid and right vertebralarteries. To examine the left side of theaortic arch and left vertebral artery, theleft brachial artery received the injectionof contrast medium by means of a powerinjector.

In the 1960s, transfemoral catheterplacement into each branch off the aortawas introduced and replaced direct sticksof the carotid and brachial arteries (22).This made it possible to selectively exam-ine the branches of the aorta to the brain.The information accumulated about thevascular supply of the posterior fossa,and in particular of the veins of thisstructure (Yun Peng Huang and BernardWolf of Mount Sinai Hospital in NewYork [23,24]), paved the way to a betterunderstanding of the posterior fossa.

Figure 4. Normal lateral pneumoencephalo-gram. The patient is upright in a chair, and thefirst 12 mL of air is injected after a removal of6 mL of fluid. Structures identified include thecisterna magna (cm), fourth ventricle (4v), syl-vian aqueduct (a), third ventricle (3v), and lat-eral ventricle (lv).

Figure 5. Lateral pneumoencephalogramshows the optic recess (O) in the third ventriclein a patient with headache and evidence of anincisural block. Patient is supine with head up.Note the fluid levels in the enlarged lateralventricles. No air is observed beyond the pre-pontine cistern (arrow). (Image courtesy ofIrvin I. Kricheff, MD, Department of Radiol-ogy, New York University Medical Center.)


Knowledge of the normal anatomy of theveins in the posterior fossa and of thepathologic alteration of these vesselscaused by lesions opened the door tomuch improved localization and diagno-sis of lesions in the posterior fossa andcerebellopontine angle (Fig 8). This led toa reduction in the need for pneumoen-cephalography and ventriculography andenabled more accurate surgical planning,which in turn translated into reduced in-traoperative and postoperative morbidityand mortality. Other technologic advancesto improve cerebral angiography includedsubtraction (Fig 6a) and magnification

(25) angiography and angiotomography(Fig 6b) (26).

Despite the considerable advances madein neuroradiology as we approached theend of the momentous decade of the1960s, there were still many lesions ofthe central nervous system we were un-able to evaluate by using these tech-niques. These included multiple sclerosisand other white matter lesions, as well asother degenerative and developmentallesions. Inflammatory lesions such as en-cephalitis and early cerebral abscesses werealso difficult to evaluate. In addition, pi-tuitary lesions were not seen with the

frequency with which they were subse-quently diagnosed by means of CT (27)and then even more so with MR imaging(28). From the 1940s through the de-velopment of CT in 1971, there wereonly incremental improvements in neuro-radiologic methods, techniques, and knowl-edge. In contrast, in the period since 1971,much more substantial changes have oc-curred more rapidly.

CT, which was initially called “com-puterized axial tomography” or “CATscanning,” was developed by GodfreyHounsfield at the EMI Laboratories in En-gland (29) and was introduced clinicallyby Jamie Ambrose of the Maida Vale Hos-pital in London in 1971 (30). Suddenly,the way the brain could be examined wasinstantaneously and forever changed.Cerebral angiography and pneumoen-cephalography were invasive proceduresand posed risks to patients, so these pro-cedures were performed only when nec-essary and were not repeated with anyfrequency, except periodically to followthe course of vascular lesions such as an-eurysms and arteriovenous malformations.

With the advent of CT, the internalstructure of the brain could be depicteddirectly, and a new era in cerebral studiesdawned. It was then possible to under-stand and diagnose almost any type ofcerebral lesion noninvasively (Fig 9). Itwas also then possible to diagnose intra-sellar, parasellar, and suprasellar lesions,and because of this the number of suchcases diagnosed increased substantially(31). The paranasal sinuses and orbitscould be examined much more accu-

Figure 6. Cerebral angiograms show glioblastoma multiforme. (a) Lateral subtracted image obtained during the midarterial phase reveals earlyvascular stain (straight arrows) and the presence of a barely perceptible draining vein (curved arrow), which is better appreciated in (b) lateralangiotomogram, which reveals the abnormal vascular stain to advantage (straight arrows) and highlights the early draining vein (curved arrow).

Figure 7. Lateral carotid arteriograms show vascular blush in a patient with an early middlecerebral infarct. (a) Image obtained during the midarterial phase shows a vascular blush (arrows)around the distal ascending branch of the sylvian triangle. (b) Image obtained during theintermediate phase shows an early draining vein (open arrow) has emerged from the blush (solidarrow). Note the intensity of the contrast medium in the vein because of lack of dilution.


rately (32). Suddenly, we had to learn theinternal structure of the orbit.

The ventricles, interfaces between grayand white matter, and calvaria could bedepicted directly in considerable detailby means of CT. Furthermore, the addi-tion of intravenous contrast medium re-sulted in the depiction of arteries andveins, dura mater, meninges, and abnor-mal vascular patterns of tumors. Theevaluation of acute cerebral changes re-sulting from trauma, infection, hemor-rhage, or metabolic alteration was possi-ble, and this in turn meant that therapycould be started immediately in manypatients, with a resultant decrease inmorbidity and increase in improved out-comes.

For example, the early diagnosis of sub-dural empyema could be made, whereasbefore the advent of CT this conditionwas fatal in more than 50% of patients(33). In the CT era, only one of 32 pa-tients with subdural empyema in one re-ported series (34) of patients died, andthis patient had venous thrombophlebi-tis. Intracranial hemorrhage could be rec-ognized, diagnosed with certainty, andlocalized (35). Angiography could thenbe properly directed in preparation forsurgery. Cerebral abscess could be recog-nized early in its development and treatedin a timely and effective manner (Fig 10)(36). The presence of hydrocephalus ortumor was appreciated, and treatmentcould be planned accurately and safely.

Thus, CT marked the beginning of anew era in which diagnosis could bemade (Fig 11) and therapy thereby insti-tuted earlier, which reduced morbidityand mortality and improved outcomes. Afurther important advantage of CT overearlier imaging technology was that itcould be repeated as often as needed tofollow the course of structural lesions.

The introduction of CT put an end tothe need for air studies, such as pneumo-encephalography and ventriculography.In addition, besides enabling examina-tion of the brain, CT could be used tolook for osseous lesions of the paranasalsinuses and orbits, as well as of the spine.Intravenously administered contrast me-dium could be used to enhance the duramater, which could aid in the evaluationof cervical or lumbar disk herniation(37).

In the 1970s, metrizamide (Amipaque),the first nonionic isosmolar contrast me-dium containing iodine, was introducedfor myelography (38). It made examina-tion easier because it did not need to beremoved, as it was absorbed into thebloodstream over time. This nonioniccontrast medium also did not causearachnoiditis and could be used in com-bination with CT to examine intraspinallesions (CT myelography) (39). It couldfurther be used with CT of the brain foropacification of the intracranial cisterns(CT cisternography) to evaluate obstruc-

tive lesions (40). It could also be used toevaluate cerebrospinal fluid leaks.

Figure 8. Right vertebral arteriograms demonstrate tumor in the right cerebellopontine angle.(a) Anteroposterior image obtained during the arterial phase reveals elevation of the marginalartery (black arrow) of the superior cerebellar artery compared with the normal configuration onthe left (arrowhead). The anterior inferior cerebellar artery (straight white arrow) on the right isforeshortened and displaced inferiorly from the internal auditory canal (a), whereas on the leftthe artery has a normal configuration with a loop (curved white arrow) seen at the internalauditory canal. (b) Anteroposterior image obtained during the venous phase shows displacedpetrosal vein (solid arrows) arced over the tumor on the right, whereas the left petrosal vein (openarrow) is normal.

Figure 9. Transverse CT scan obtained afterthe administration of contrast material depictsa large ring lesion (arrow) in the left frontalcorticomedullary junction. The patient haddeveloped right hemiparesis 10 months afterradiation therapy for a right parasagittal le-sion. No ring was seen on the CT scan (notshown) obtained before the administration ofcontrast material, which excludes abscess, me-tastasis, or glioblastoma. This was supportedby lack of substantial edema and the thicken-ing of the medial margin of the ring lesion. Atsurgery, radiation necrosis was confirmed.

Figure 10. Transverse postcontrast CT scanobtained in the inferior frontal region showscerebral abscess after fracture of frontal bone. Aring lesion (curved arrow), which was also seenon the precontrast CT scan (not shown), isdemonstrated. Although no thinning is seenon the medial margin, the budding of a newlesion from the anterior margin of the ring(straight arrow) suggests an abscess, which wasconfirmed at surgery.


Progressive improvements over time,including improved signal-to-noise ratioand contrast-to-noise ratio with mark-edly reduced data acquisition and pro-cessing times, have resulted in substan-tial improvements in imaging qualityand applications. New scanners havebeen developed with spiral motion andmultisection capabilities that allow fasteracquisition times with ever thinner sec-tions that yield detailed anatomic andvascular studies (41). Aneurysms can bedepicted directly and more completely(42). Perfusion imaging techniques arecurrently advancing and rival thoseavailable with MR imaging (43). Thus, CTcan image the brain, orbits, and spine,and our knowledge of congenital, devel-opmental, white matter, degenerative,traumatic, inflammatory, and neoplasticlesions has progressed by a quantumleap.

CT examination of the neck has al-lowed evaluation of the deep and super-ficial cervical lymph nodes. The aerodi-gestive tract can be examined, and thecongenital and developmental lesions ofthe soft tissues of the neck can be diag-nosed and localized (44–46). Evaluationof the cervical lymph nodes made possi-ble by CT has led to more accurate clas-sification of lymph node groups and hasimproved tumor grading and staging ofhead and neck neoplasms (47–49). CThas also led to similar improvements in

the diagnostic accuracy and staging oftumors of the orbits, paranasal sinuses,temporal bones, and skull base, whichvirtually eliminates the indications forconventional radiographs and tomo-grams of these regions (50).

Progress in neuroradiology continuedrapidly and inexorably with the develop-ment of MR imaging in the late 1970sand early 1980s, close on the heels of CT.Particular advantages of MR imaging arethat it can be performed in any plane andwith various pulse sequences, which re-veal more detailed cerebral anatomy,such as the red nuclei and the substantianigra (51), than was previously possiblewith any earlier diagnostic imaging mo-dality. The anatomy observed by meansof MR imaging is exquisite in its contrastresolution and rivals the appearance ofactual gross anatomic cerebral slices.

MR imaging has replaced CT in theimaging of the brain and spine, except incertain specific instances (52). These in-clude acute subarachnoid hemorrhage,three-dimensional reconstructions of an-eurysms with helical images, and imag-ing in acutely ill or agitated patients be-cause of rapid imaging time. Patients inwhom MR imaging is contraindicated arepatients with a pacemaker or metallic de-vices, such as aneurysm clips, that maymove during examination and patientswith calcified or ossified intracranial le-sions, including skull base tumors and

temporal bone lesions. MR imaging canbe used to help obtain more specific his-tologic diagnoses, assess for complica-tions (eg, hemorrhage or hydrocephalus)in the immediate postoperative interval,and depict metallic fragments within theorbit (52). The development of paramag-netic contrast media that are safe andwell tolerated, coupled with the detailedanatomic depiction possible with MR im-aging, has provided a unique opportu-nity to examine the brain in detail toexplain almost any lesion that affects thehuman brain.

As the American Society of Neuroradi-ology matured, subspecialties within thesociety slowly developed and evolved.These included interventional neuroradi-ology and head and neck radiology, andthen pediatric neuroradiology and thespine society. The American Society ofNeuroradiology now consists of generalneuroradiology and the subspecialties;these each have their own leadership butare integrated with each other, which hasenabled greater growth of the specialty ofneuroradiology.

Further advances that add to our knowl-edge and expand the horizons and appli-cations of neuroimaging continue to bemade at a rapid pace. For example, fasteracquisition times have made possiblenew sequences such as fluid-attenuatedinversion recovery, or FLAIR. This haspermitted improved depiction of intra-

Figure 11. Images obtained in a young adult woman with lupus erythematosis who presented with left hemiparesis. (a) Transverse contrastmedium–enhanced CT scan reveals a large hypoattenuation zone (arrows) affecting temporal white matter without any evidence of contrastenhancement, which suggests a venous infarct. (b) Lateral right common carotid arteriogram obtained during the venous phase with subtractionreveals occlusion of the sylvian vein by its absence (open arrow), and major venous drainage is via the vein of Labbe (solid arrows) and to a lesserextent a frontal vein (F). A right common carotid arteriogram (not shown) obtained during the arterial phase revealed no abnormality.


cranial lesions, as well as evaluation ofsubarachnoid fluid, so that leptomenin-geal disease, subarachnoid blood, pus, orany fluid with an elevated protein con-tent can be made visible by altering thesignal intensity of the subarachnoidspaces (53). In addition, MR angiographynow allows direct depiction of blood flowin arteries or veins with or without theuse of contrast medium (54).

Faster imagers with stronger gradientshave led to the development of echo-planar MR imaging, which is capable ofin vivo functional neuroimaging (55). Inparticular, one can now observe and lo-calize stimulated cerebral activity (eg,motor, sensory, expressive, or receptivespeech and memory), which has vastlyexpanded our understanding of how thebrain works in health and in disease andhas already assumed an important placein patient examination and surgical plan-ning (56,57).

Another technique, diffusion-weightedMR imaging, can be used to examine al-terations in micromolecular water mo-tion, which allows the early detection ofconditions restricting motion of water atthe cellular level (58). To date, this mo-dality has been most effective in identi-fying an early stroke, thereby enablingand improving appropriate therapy plan-ning. Diffusion-weighted imaging is nowbeing evaluated for possible use in iden-tifying tumors and distinguishing tumorfrom necrosis and edema on the basis ofvariations in diffusion rates and particu-lar changes in the apparent diffusion co-efficient (59). It is also being used to de-pict white matter tracts (Fig 12) as an aidto stimulated cerebral activity and to ex-amine connectivity within the brain (60).

Perfusion imaging, another technique,is used to examine cerebral blood vol-ume, cerebral blood flow, and the meantransit time of blood within the brain bymeans of measuring the first pass of abolus of paramagnetic contrast mediumthrough the brain, with multiple sectionsobtained in microseconds. This tech-nique may be used to identify the moreactive components of tumors by reveal-ing foci with increased uptake of contrastmedium. It is hypothesized that tumormay also thus be separated from necrosisin a patient after treatment (61). In apatient who has had a stroke, a mismatchbetween diffusion and perfusion may beused to identify the ischemic but still vi-able penumbra, and this informationcould be important in therapeutic deci-sion making (62).

In the examination of the spine, MRimaging has today almost completely re-

placed myelography. It is effective andaccurate in the assessment of spondylo-sis; degenerative disk disease; traumaticlesions of the spine, including epiduralhematoma; inflammatory lesions of thedisk, bone, and cord; and vertebral andspinal cord neoplasms (63,64). For thefirst time, the spinal cord can be exam-ined intrinsically directly. Intravenousinjection of paramagnetic contrast me-dium may be helpful in MR imaging ofthe head and neck by revealing the peri-neural spread of tumor (65). MR imagingmay reveal vascular lesions by demon-strating flow voids. In the spinal canal,diffusion-weighted imaging may be use-ful in separating benign from malignantlesions affecting the vertebral bodies.

In multiple sclerosis, although MR im-aging often reveals the lesions and canaid in discriminating acute from chroniclesions, the neurologist’s clinical evalua-tion is still the primary method of diag-nosis. MR imaging, however, has proveduseful in evaluating therapeutic optionsby means of monitoring lesion changesover time and helping to delay or preventnew lesions.

MR imaging with rapid imaging timespermits functional neuroimaging, whichis rapidly opening up our understandingof cerebral activity. With the availabilityof new imagers that have field strengthsof 3 T or more and are capable of a sub-stantial increase in the rate and quantityof data acquisition, and a two to threetimes increase in resolution, our under-standing of cerebral activity will surelyincrease further (66).

The accuracy and value of MR spectros-copy should increase because of im-proved data acquisition, multivoxel tech-niques, and smaller voxels of 1 cm or less(67). By clearly showing the biochemistryof the brain, MR spectroscopy shouldprovide information on neurologic disor-ders even earlier than does MR imag-ing, because in some cases biochemicalchanges occur earliest in the evolution ofsuch diseases (68). Use of elements otherthan hydrogen, such as sodium, carbon,and fluorine, may be possible because ofincreases in the available signal with 3-Tor even more powerful magnets, and thisshould further open new pathways of in-formation. Already, more powerful mag-nets with field strengths in the range of6–9 T are being investigated to provideMR spectroscopic information in humansubjects, so biochemical changes mayprovide additional new and useful infor-mation (69).

Our specialty has made quantum leapsin its ability to depict the structural le-

sions of the brain, spine, head, and neck,while reducing patient discomfort andmorbidity. This progress in lesion detect-ability has been possible as newer modal-ities have provided more information. Inaddition, much has been learned aboutthe natural history and evolution of dis-ease through our ability to repeat nonin-vasive diagnostic examinations and tofollow the patient’s clinical course.

The chronology of neuroradiology,which started with the discovery of x raysby Roentgen in 1895 and his applicationof them in x-ray imaging, was quicklyfollowed by early intellectual and techni-cal advances, beginning with conven-tional radiography in the early 1900s, fol-lowed by ventriculography in 1918 andpneumoencephalography in 1919. Thenext important stride came in 1927 whenangiography was developed. After this,serial changers and power injectors madeimproved imaging possible following di-rect arterial sticks. Catheter angiography,which was developed in the 1960s, re-placed direct sticks.

In 1971 came the technologic advance,that for neuroradiology, was comparablewith the trip to the moon by means ofspace flight. This was the year in whichCT was introduced. A revolutionary non-invasive approach to brain and then

Figure 12. Transverse MR image obtained byusing a diffusion tensor imaging sequencewith multiple diffusion gradient orientationsto take advantage of the anisotropic imaginghighlighting white matter tracts. In this singleimage from a sequence of multiple images, thefollowing tracts are identified: arcuate fascicu-lus (small straight arrows), corticospinal tract(arrowheads), internal capsule anterior limb(curved arrows), fronto-occipital tract (largestraight arrows).


spine imaging was possible. We were ableto look inside the brain for the first timeand to observe its internal structure.Soon thereafter came MR imaging, whichmarked an even greater leap forwardthan CT. Structural imaging made sub-stantial progress, and then came physio-logic imaging and the development offunctional imaging with stimulated cere-bral activation, similar to positron emis-sion tomographic scanning, as well asperfusion and diffusion.

With the advent of MR spectroscopy,we are at the beginning of biochemicalimaging. The availability of newer mag-nets with increasing power at 3 T andthen with 6–9 T will open the window ofour diagnostic abilities and knowledgeeven wider.

We were most fortunate to start in neu-roradiology during the age of angiogra-phy and the beginning of pathophysio-logic studies, and then to be a part of themagical changes that have occurred sincethen, including CT and MR imaging. AsMR imaging continues to improve, newvistas in neuroradiology will be openedup that will provide more accurate ana-tomic, physiologic, and biochemical in-formation about disorders of the nervoussystem.

Acknowledgments: We thank Irvin I. Kri-cheff, MD, for his support and Marites A.Trevino for her work on the manuscript.

References1. Pfahler G. Cerebral skiagraphy: transac-

tions of the American Roentgen Ray Soci-ety—5th Annual Meeting. Am J Roentge-nol 1904; 4:174–186.

2. Schuller A. Roentgen diagnosis of diseasesof the head. Stocking FF, trans. St Louis,Mo: Mosby, 1918.

3. Dandy WE. Ventriculography followingthe injection of air into the cerebral ven-tricles. AJR Am J Roentgenol 1919; 6:26–36.

4. Dandy WE. Roentgenography of thebrain after the injection of air into thespinal canal. Ann Surg 1919; 70:397.

5. Moniz EL. L’Angiographie cerebrale.Paris, France: Masson & Cie 1934; 142–214.

6. Davidoff LM, Dyke CG. The normal en-cephalogram. Philadelphia, Pa: Lea & Fe-biger 1937.

7. Mixter WJ, Barr JS. Rupture of the inter-vertebral disk with involvement of thespinal canal. N Engl J Med 1934; 211:210–215.

8. Shapiro R. Myelography. 4th ed. Chicago,Ill: Yearbook Medical Publishers, 1984.

9. Taveras JM, Wood EH. Diagnostic neuro-radiology. 2nd ed. Vol 1. Baltimore, Md:Williams & Wilkins, 1976; 398–542.


11. Potts DG. A new universal head unit.

Am J Roentgenol Radium Ther Nucl Med1965; 95:957–961.


13. Kuhn RA. Brachial cerebral angiography.J Neurosurg 1960; 17:955.

14. Gould PL, Peyton WT, French LA. Verte-bral angiography by retrograde injectionof the brachial artery. J Neurosurg 1955;12:369–374.

15. Aaron JO, Taveras JM. The angiographiclocalization of supratentorial masses. In:Taveras JM, Ferrucci JT, eds. Radiology-diagnosis-imaging and intervention. Vol3. Philadelphia, Pa: Lipincott, 1989; 1–9.

16. Elias DA, Weinberg PE. Vascular stains inintracranial tumors. In: Taveras JM, Fer-rucci JT, eds. Radiology-diagnosis-imag-ing and intervention. Vol 3. Philadelphia,Pa: Lipincott, 1989; 1–15.

17. Leeds NE, Taveras JM. Changes in localcirculation time in frontal and parietaltumors by rapid serial angiography. ActaRadiol Diagn 1963; 1:332–342.

18. Greitz T. A radiologic study of the brain:circulation by rapid serial angiography ofthe carotid artery. Acta Radiol 1965; Sup-plement 140.

19. Leeds NE, Taveras JM. Dynamic factors indiagnosis of supratentorial brain tumorsby cerebral angiography. Philadelphia,Pa: Saunders, 1969; 38–86.

20. Leeds NE, Goldberg HI. Abnormal vascu-lar patterns in benign intracranial le-sions: pseudotumors of the brain. Am JRoentgenol Radium Ther Nucl Med 1973;118:576–585.

21. Sheldon PA. A special needle for percuta-neous vertebral angiography. Br J Radiol-ogy 1956; 29:231–232.

22. Hinck VC, Judkins MP, Paxton HD. Sim-plified selective femorocerebral angiogra-phy. Radiology 1967; 89:1048–1052.

23. Huang YP, Wolf BS. The veins of the pos-terior fossa: superior or galenic draininggroup. Am J Roentgenol Radium TherNucl Med 1965; 95:808–821.

24. Huang YP, Wolf BS. Precentral cerebellarvein in angiography. Acta Radiol Diagn1966; 5:250–262.

25. Leeds NE, Issard HJ, Goldberg HI, Culli-nan RT. Serial magnification cerebral an-giography. Radiology 1968; 90:1171–1175.

26. Rosa M. Value of angiotomography inplanning operative treatment of internalcarotid artery aneurysms. Neuoradiology1971; 3:82–91.

27. Syvertsen A, Haughton VM, Williams AL,Cusick JF. The computed tomographicappearance of the normal pituitary glandand pituitary microadenomas. Radiology1979; 133:385–391.

28. Newton DR, Dillon WP, Norman D, et al.Gd-DTPA-enhanced MR imaging of pitu-itary adenomas. AJR Am J Roentgenol1989; 10:949–953.

29. Hounsfield GH. Computerized transverseaxial scanning (tomography). I. Descrip-tion of system. Br J Radiol 1973; 46:1016–1022.

30. Ambrose J. Computerized transverse axialscanning (tomography). II. Clinical appli-cation. Br J Radiol 1973; 46:1023–1047.

31. Naidich TP, Pinto RS, Kushner MJ, et al.Evaluation of sellar and parasellar massesby computed tomography. Radiology 1976;121:641–646.

32. Tadmor R, Davis KR, Weber AL, et al.Direct coronal computerized tomographyof the skull and facial structures: prelim-inary evaluation of direct coronal sec-tions. Comput Tomogr 1977; 1:211–215.

33. Kaufman DM, Leeds NE. Focal angio-graphic abnormalities with subdural em-pyema. Neuroradiology 1976; 11:169–173.

34. Zimmerman RD, Leeds NE, Danziger A.Subdural empyemas. Radiology 1984;150:417–422.

35. Kendall BF, Lee BCP, Claveria C. Comput-erized tomography and angiography insubarachoid hemorrhage. Br J Radiol1976; 49:483–501.

36. New PFJ, Davis KR, Ballantine HT. Com-puted tomography in cerebral abscess.Radiology 1976; 121:641–646.

37. Russell EJ, Dangelo CM, Zimmerman RD,et al. Cervical disk herniation: CT dem-onstration after contrast enhancement.Radiology 1984; 152:703–712.

38. Ahn HS, Rosenbaum AE. Lumbar myelog-raphy with metrizamide: supplementarytechnique. AJR Am J Roentgenol 1981;136:547–551.

39. Anand AK, Lee BC. Plain and metriz-amide CT of lumbar disc disease: compar-ison with myelography. AJNR Am J Neu-roradiol 1982; 3:567–571.

40. Greitz T, Hindmarsh T. Computer as-sisted tomography of intracranial CSF cir-culation using a water soluble contrastmedium. Acta Radiol Diagn 1974; 15:497–507.

41. Schwartz RB, Jones KM, Chernoff DM, etal. Common carotid artery bifurcation:evaluation with spiral CT—work inprogress. Radiology 1992; 185:513–519.

42. Brown JH, Lustrin ES, Lev MH, et al.Characterization of intracranial aneu-rysms using CT angiography. AJR Am JRoentgenol 1997; 169:889–893.

43. Hunter GJ, Hamburg LM, Ponzo JA, et al.Rapid assessment of cerebral perfusionand arterial anatomy in hyperacutestroke with 3D functional computed to-mography: early clinial results. AJNRAm J Neuroradiol 1998; 19:29–37.

44. Mukherji S, Castillo M. A simplified ap-proach to the spaces of the suprahyoidneck. Radiol Clin North Am 1998; 36:761–780.

45. Sigal R. Infrahyoid neck. Radiol ClinNorth Am 1998; 36:781–799.

46. Reede DL, Whelan MA, Bergeron RT.Computed tomograpy of the infrahyoidneck: pathology. Radiology 1982; 145:399–402.

47. Som P. Lymph nodes of the neck. Radiol-ogy 1987; 165:593–600.

48. Curtin H, Ishwaran H, Mancuso A, et al.Comparison of CT and MR imaging instaging of neck metastases. Radiology1998; 207:123–130.

49. Som PM, Curtin HD, Mancuso A. An im-aging-based classification for the cervicalnodes designed as an adjunct to recentclinically based nodal classifications.Arch Otolaryngol Head Neck Surg 1999;125:388–396.

50. Shaffer KA, Haughton VM, Wilson CR.High resolution computed tomographyof the temporal bone. Radiology 1980;134:409–414.

51. Brant-Zawadski M, Norman D, NewtonTH, et al. Magnetic resonance of the


brain: the optimal screening technique.Radiology 1984; 152:71–77.

52. Leeds NE, Kumar AJ, Jackson EF. Neuro-imaging of brain tumors. In: Evans RW,ed. Diagnostic testing in neurology. Phil-adelphia, Pa: Sauders, 1999; 169–199.

53. Singer MB, Atlas SW, Drayer BP. Sub-arachnoid space disease: diagnosis withfluid-attenuated inversion-recovery MRimaging and comparison with gadolini-um-enhanced spin-echo MR imaging—blinded reader study. Radiology 1998;208:417–422.

54. Masaryk TJ, Modic MT, Ross JS, et al. In-tracranial circulation: preliminary clini-cal experience with three-dimensionalvolume MR angiography. Radiology1989; 171:793–799.

55. Rosen BR, Belliveau JW, Aronen HJ, et al.Susceptibility contrast imaging of cere-bral blood volume: human experience.Magn Reson Med 1991; 22:293–299.

56. Jack JR Jr, Thompson R, Butts RK, et al.Sensory motor cortex: presurgical map-ping with functional MR imaging and in-vasive cortical mapping. Radiology 1994;190:85–92.

57. van der Kallen BFW, Morrison L, YetkinFZ, et al. Hemispheric language domi-

nance as studied by functional MR imag-ing: preliminary study in healthy volun-teers and patients with epilepsy. AJNRAm J Neuroradiol 1998; 19:73–77.

58. Beauchamp NJ Jr, Ulug AM, Passe TJ,Vanzyl PCM. MR diffusion imaging instroke: review and controversies Radio-Graphics 1998; 18:1269–1283.

59. Sugahara T, Korogi Y, Kochi M, et al. Use-fulness of diffusion-weighted MRI withecho-planar technique in the evaluationof cellularity in gliomas. J Magn ResonImaging 1999; 9:53–60.

60. Pajevic S, Pierpaoli C. Color schemes torepresent the orientation of anisotropictissues from diffusion tensor data: appli-cation to white matter fiber tract map-ping in the human brain. Magn ResonMed 1999; 42:526–540.

61. Aronen HJ, Gazit IE, Louis DN, et al. Cere-bral blood volume maps of gliomas: com-parison with tumor grade and histologicfindings. Radiology 1994; 191:41–51.

62. Kucharczyk J, Vexler ZS, Roberts TP, et al.Echo-planar perfusion-sensitive MR im-aging of acute cerebral ischemia. Radiol-ogy 1993; 188:711–717.

63. Modic MT. Degenerative diseases of thespine. In: Modic M, Masaryk T, Ross J,eds. Magnetic resonance imaging of the

spine. Chicago, Ill: Yearbook MedicalPublishers, 1989; 109–120.

64. Zimmerman RA, Bilaniuk LT. Imagingof tumor of the spinal canal and cord.Radiol Clin North Am 1988; 26:965–1007.

65. Ginsberg LE. Imaging of perineural tu-mor spread in head and neck cancer.Semin Ultrasound CT MR 1999; 20:175–186.

66. Pan JW, Vaughan JT, Kuzniecky RI, etal. High resolution neuroimaging at4.1 T. Magn Reason Med 1995; 33:915–921.

67. Posse S, Cuernod CA, Risinger R, et al.Anomalous transverse relaxation inH spectroscopy in human brain at 4Tesla. Magn Reson Med 1995; 33:246–252.

68. Jarvik JG, Lenkinski RE, Grossman RI, etal. Proton MR spectroscopy of HIV-in-fected patients: characterization of ab-normalities with imaging and clinicalcorrelation. Radiology 1993; 186:739–744.

69. Thulborn KR. Why neuroradiologistsshould consider very-high-field magnetsfor clinical applications of functionalmagnetic resonance imaging. Top MagnReson Imaging 1999; 10:1–2.


reﬂections - semantic scholar · the thoracic or cervical region, to prevent the oily contrast...

Documents