frank p. dawry infrequently performed studies in nuclear medicine j nucl med technol 2008;...

Frank P. Dawry

Infrequently Infrequently Performed Studies Performed Studies

in Nuclear in Nuclear MedicineMedicine

J Nucl Med Technol 2008; 36:132–143J Nucl Med Technol 2008; 36:132–143

J Nucl Med Technol 2008; 36:132–143 Frank P. Dawry

DACROSCINTIGRAPHY DACROSCINTIGRAPHY (LACRIMAL GLAND STUDY)(LACRIMAL GLAND STUDY)

• A method of evaluating the nasolacrimal A method of evaluating the nasolacrimal drainage system. drainage system.

• It is used to demonstrate patency of the It is used to demonstrate patency of the system and to localize the general area of system and to localize the general area of obstruction, which can be important for obstruction, which can be important for presurgical planning. presurgical planning.

• It also can be used postoperatively to It also can be used postoperatively to evaluate whether the surgery was evaluate whether the surgery was successful.successful.


DACROSCINTIGRAPHY DACROSCINTIGRAPHY (LACRIMAL GLAND STUDY)(LACRIMAL GLAND STUDY)• located in the lateral located in the lateral

superior portion of each superior portion of each orbit. orbit.

• are responsible for the are responsible for the production of tears that production of tears that function to clean and function to clean and lubricate the eyes.lubricate the eyes.

• Tears are excreted from Tears are excreted from the lacrimal gland and the lacrimal gland and transit across the surface transit across the surface of the eye to the of the eye to the nasolacrimal apparatus nasolacrimal apparatus situated medial to the eye.situated medial to the eye.

superior canaliculus (SC)inferior canaliculus (IC),common canaliculus (CC)nasolacrimal sac (NS)Nasolacrimal duct (ND).



• Problems with insufficient tear Problems with insufficient tear formation may be caused by a variety formation may be caused by a variety of medical problems including of medical problems including

– Sj¨ogren’s syndromeSj¨ogren’s syndrome– inflammatory conditionsinflammatory conditions– AllergiesAllergies– radiation treatmentradiation treatment– MedicationsMedications– ageage– environmental conditions.environmental conditions.



• Problems with excessive tear formation Problems with excessive tear formation (Epiphora) may be caused by a variety of medical (Epiphora) may be caused by a variety of medical problems including problems including

– IrritationIrritation– AllergiesAllergies– emotions,emotions,– a variety of environmental factorsa variety of environmental factors– blockage of the nasolacrimal system that is prohibiting proper blockage of the nasolacrimal system that is prohibiting proper

tear drainagetear drainage• inflammatory processesinflammatory processes• mucus plugmucus plug• a dacrolith (stone)a dacrolith (stone)• TraumaTrauma• congenital abnormalities,congenital abnormalities,• radiation therapyradiation therapy



procedureprocedure• Encourage the patient to allow the tears to Encourage the patient to allow the tears to

drain down the lateral aspect of the face; drain down the lateral aspect of the face; – this is preferable to having them fall naturally this is preferable to having them fall naturally

anterior to the face, which may interfere with the anterior to the face, which may interfere with the imaging of the nasolacrimal duct and nasal cavity.imaging of the nasolacrimal duct and nasal cavity.

• After the eyedrops are administered, the After the eyedrops are administered, the patient is placed in a sitting position for patient is placed in a sitting position for imaging. imaging.

• Immobilizing the patient’s head may be Immobilizing the patient’s head may be necessary to obtain optimal imaging.necessary to obtain optimal imaging.



procedure continuedprocedure continued• The patient must remove eyewear, including contact The patient must remove eyewear, including contact

lenses, before starting the study. lenses, before starting the study. • Approximately 3.7 MBq (0.1 mCi) of 99mTc-Approximately 3.7 MBq (0.1 mCi) of 99mTc-

pertechnetate in a saline solution is administered per pertechnetate in a saline solution is administered per eye to the supine patient, with an eyedropper or a eye to the supine patient, with an eyedropper or a needleless 1-mL tuberculin syringe.needleless 1-mL tuberculin syringe.– Ensure that eyedrop administration is performed with care to Ensure that eyedrop administration is performed with care to

prevent contamination of the patient’s face with radioactive prevent contamination of the patient’s face with radioactive dropsdrops

– If patients are teary, encourage them to blot, not smear, If patients are teary, encourage them to blot, not smear, tears away with a tissue to limit potential of contamination. tears away with a tissue to limit potential of contamination.

– Encourage the patient to allow the tears to drain down the Encourage the patient to allow the tears to drain down the lateral aspect of the facelateral aspect of the face



procedure continuedprocedure continued

• After the eyedrops are administered, the patient After the eyedrops are administered, the patient is placed in a sitting position for imaging. is placed in a sitting position for imaging.

• Immobilizing the patient’s head may be Immobilizing the patient’s head may be necessary to obtain optimal imaging; this may necessary to obtain optimal imaging; this may include securing the patient’s head to the include securing the patient’s head to the camera face or using an immobilizing vacuum camera face or using an immobilizing vacuum pillow to limit patient motion. pillow to limit patient motion.

• A pinhole collimator (insert, 1–2 mm) or low-A pinhole collimator (insert, 1–2 mm) or low-energy all-purpose collimator with zoom may be energy all-purpose collimator with zoom may be used for acquisition.used for acquisition.



procedure continuedprocedure continued• Dynamic or static imaging may be Dynamic or static imaging may be

obtained.obtained.– For dynamic imaging, use 10 s/frame for 1–2 For dynamic imaging, use 10 s/frame for 1–2

min followed by 1 min/frame for 15–20 min. min followed by 1 min/frame for 15–20 min. – Static imaging includes a 1-min image Static imaging includes a 1-min image

obtained immediately after the obtained immediately after the administration of eyedrops, followed by 1-administration of eyedrops, followed by 1-min static images obtained at 5, 10, 15, and min static images obtained at 5, 10, 15, and 20 min.20 min.



interpretationinterpretation• Visualization of the nasolacrimal sac within 1 min after Visualization of the nasolacrimal sac within 1 min after

eyedrop administration, with drainage of activity from the eyedrop administration, with drainage of activity from the nasolacrimal duct into the nasal cavity within 5 min, is nasolacrimal duct into the nasal cavity within 5 min, is considered a normal finding. considered a normal finding.

• Drainage through the nasolacrimal duct to the nasal cavity Drainage through the nasolacrimal duct to the nasal cavity can be variable, however, and others consider visualization can be variable, however, and others consider visualization of the nasal cavity within 10–15 min a normal finding.of the nasal cavity within 10–15 min a normal finding.

• Radioactivity not visualized after this time period may Radioactivity not visualized after this time period may indicate a blockage.indicate a blockage.

• Evaluating both eyes simultaneously will be better for Evaluating both eyes simultaneously will be better for recognizing subtle differences between the drainage of recognizing subtle differences between the drainage of each eye. assuming that one eye is functioning normally, each eye. assuming that one eye is functioning normally, but there still may be bilateral obstruction of varying but there still may be bilateral obstruction of varying degrees.degrees.



normalnormal

Normal lacrimal gland studyat 3 time points demonstrating bilateraldrainage from eyes into nasal cavity.



bilateral obstructionbilateral obstruction

Dacroscintigraphy study demonstrating bilateral obstruction. Images at 3 time points reveal bilateral obstruction within nasolacrimal ducts (arrows).


LEVEEN SHUNT STUDYLEVEEN SHUNT STUDY

• Designed to help manage Designed to help manage patients with chronic ascitis.patients with chronic ascitis.– excess of fluid accumulation in the excess of fluid accumulation in the

peritoneal cavity. Possibly due to a peritoneal cavity. Possibly due to a variety of medical problems, variety of medical problems, including liver failure and kidney including liver failure and kidney disease.disease.



• The LeVeen shunt is a peritoneovenous shunt, The LeVeen shunt is a peritoneovenous shunt, intended to drain the ascites into the venous intended to drain the ascites into the venous system.system.

• It is surgically placed in the peritoneal cavity and It is surgically placed in the peritoneal cavity and has a 1-way valve that connects into the patient’s has a 1-way valve that connects into the patient’s jugular vein, which then empties into the superior jugular vein, which then empties into the superior vena cava (SVC). vena cava (SVC).

• The valve opens when the pressure in the The valve opens when the pressure in the abdomen exceeds the pressure in the SVC.abdomen exceeds the pressure in the SVC.

• Therefore, there should be an intermittent Therefore, there should be an intermittent emptying of fluid from the peritoneal cavity into emptying of fluid from the peritoneal cavity into the venous system after proper LeVeen shunt the venous system after proper LeVeen shunt placement.placement.



• If the patient’s ascitis is not alleviated If the patient’s ascitis is not alleviated after the shunt placement or if there is a after the shunt placement or if there is a subsequent recurrence of ascitis, several subsequent recurrence of ascitis, several possibilities may be the causepossibilities may be the cause– worsening of the patient’s conditionworsening of the patient’s condition– changes in the patient’s dietchanges in the patient’s diet– changes in the patient’s medical management.changes in the patient’s medical management.– mechanical obstruction in the tubingmechanical obstruction in the tubing

• Valve failureValve failure• thrombosisthrombosis


LEVEEN SHUNT STUDYLEVEEN SHUNT STUDYprocedureprocedure

• No patient preparationNo patient preparation• Physician delivers an intraperitoneal injection of 185 MBq Physician delivers an intraperitoneal injection of 185 MBq

(5 mCi) of 99m-Tc-macroaggregated albumin (MAA).(5 mCi) of 99m-Tc-macroaggregated albumin (MAA).• patient should be instructed to roll from one side to the patient should be instructed to roll from one side to the

other, to mix the radioactive injection with the ascitic fluid.other, to mix the radioactive injection with the ascitic fluid.• Static images of the abdomen and chest are obtained at Static images of the abdomen and chest are obtained at

15, 30, 45, and 60 min after injection. If required, images 15, 30, 45, and 60 min after injection. If required, images may be obtained up to 4 h after injection.may be obtained up to 4 h after injection.

• When the LeVeen shunt is functional, the injected 99mTc-When the LeVeen shunt is functional, the injected 99mTc-MAA travels to the lungs and lodges in the capillaries, as MAA travels to the lungs and lodges in the capillaries, as with a perfusion lung study. with a perfusion lung study. – The lungs should become visualized within 1 h of imaging The lungs should become visualized within 1 h of imaging

after the 99mTc-MAA intraperitoneal injection. after the 99mTc-MAA intraperitoneal injection. – However, lung visualization may occur as early as 10 minutes However, lung visualization may occur as early as 10 minutes

post injection.post injection.


LEVEEN SHUNT STUDYLEVEEN SHUNT STUDYNormalNormal

Images at 10, 20, and 30 min demonstrate rapid arrival of 99mTc-MAA in lungs with increasing activity over time, confirming patency of shunt. Activity inferior to lungs represents injected activity in peritoneal cavity.


SCINTIMAMMOGRAPHYSCINTIMAMMOGRAPHY

• Scintimammography has been shown to Scintimammography has been shown to be an effective option for early be an effective option for early detection of breast cancer to detection of breast cancer to differentiate benign from malignant differentiate benign from malignant lesions in:lesions in:

• Patients who have dense breast tissuePatients who have dense breast tissue• Patients who have breast implantsPatients who have breast implants• Patients who have had previous breast surgeryPatients who have had previous breast surgery• Patients who have had radiation therapy.Patients who have had radiation therapy.

• may also help to identify axillary node may also help to identify axillary node involvement.involvement.


SCINTIMAMMOGRAPHY SCINTIMAMMOGRAPHY procedureprocedure

• Requires no specific patient Requires no specific patient preparationpreparation

• Because of the private nature of the Because of the private nature of the examination, professional conduct examination, professional conduct should be maintained throughout the should be maintained throughout the study. study.

• The technologist should also ensure The technologist should also ensure that the patient is aware of the steps that the patient is aware of the steps of the procedure.of the procedure.



• After the patient’s history is obtained After the patient’s history is obtained and the study has been discussed, the and the study has been discussed, the patient is asked to remove all clothing patient is asked to remove all clothing and jewelry from the waist up. and jewelry from the waist up.

• Hospital gowns should be supplied to Hospital gowns should be supplied to the patient, with the first gown worn the patient, with the first gown worn with the opening to the front and a with the opening to the front and a second one used for privacy with the second one used for privacy with the opening at the back until imaging opening at the back until imaging begins.begins.



• The patient is injected with 740–1,110 MBq (20–30 The patient is injected with 740–1,110 MBq (20–30 mCi) 99mTc-sestamibi in the arm contralateral to mCi) 99mTc-sestamibi in the arm contralateral to the breast with the suspected lesion.the breast with the suspected lesion.

• The injection should be administered through a 3-The injection should be administered through a 3-way stopcock mechanism or an intravenous way stopcock mechanism or an intravenous catheter to ensure no dose infiltration.catheter to ensure no dose infiltration.– Infiltrated doses may cause lymph node uptake that could Infiltrated doses may cause lymph node uptake that could

possibly be mistaken for a positive breast lesion or possibly be mistaken for a positive breast lesion or metastatic disease. metastatic disease.

• If lesions are suspected in both breasts, or if the If lesions are suspected in both breasts, or if the contralateral arm is not a viable option, a pedalis contralateral arm is not a viable option, a pedalis vein should be used as the route of administration.vein should be used as the route of administration.

• Imaging may begin 5–10 min after injection.Imaging may begin 5–10 min after injection.



• Positioning is critical to a good studyPositioning is critical to a good study• 3 static acquisitions are obtained: 3 static acquisitions are obtained:

• Left lateral breast, Left lateral breast, • right lateral breast,right lateral breast,• anterior chestanterior chest


SCINTIMAMMOGRAPHY SCINTIMAMMOGRAPHY procedure – staticsprocedure – statics

Lateral Lateral • Patients are positioned prone on the Patients are positioned prone on the

imaging table for the lateral views. imaging table for the lateral views. • An imaging table equipped with a An imaging table equipped with a

mattress, preferably constructed with mattress, preferably constructed with foam, with a cut-out for the breasts allows foam, with a cut-out for the breasts allows for better image quality and provides for better image quality and provides patient comfort. patient comfort.

• The prone position allows for the breasts The prone position allows for the breasts to be maximally separated from the chest to be maximally separated from the chest and abdominal wall.and abdominal wall.



Lateral Lateral • Accidental compression of the breast against Accidental compression of the breast against

the table may cause false abnormalitiesthe table may cause false abnormalities• The breast being imaged must be hanging The breast being imaged must be hanging

completely pendant.completely pendant.



Anterior Anterior • The anterior chest view is imaged with the The anterior chest view is imaged with the

patient in the supine position with the arms patient in the supine position with the arms raised to include visualization of both axilla.raised to include visualization of both axilla.

• Each static is taken for a total of 10 min Each static is taken for a total of 10 min with a 256 matrix with a parallelhole, high-with a 256 matrix with a parallelhole, high-resolution collimator. resolution collimator.

• Zoom may be used to ensure abdominal Zoom may be used to ensure abdominal organs and structures in the neck are organs and structures in the neck are excluded from the field of view.excluded from the field of view.


SCINTIMAMMOGRAPHYSCINTIMAMMOGRAPHY

• A focal accumulation of A focal accumulation of 99mTc-sestamibi in the 99mTc-sestamibi in the breast that is greater breast that is greater than the surrounding than the surrounding breast tissue is breast tissue is considered a positive considered a positive finding. finding. – Lesions less than 7–8 mm Lesions less than 7–8 mm

are less likely to be are less likely to be visualized with visualized with mammoscintigraphy mammoscintigraphy because of the limited because of the limited resolution of the camera.resolution of the camera.


SCINTIMAMMOGRAPHYSCINTIMAMMOGRAPHY• The location of the lesion in the breast may also inhibit The location of the lesion in the breast may also inhibit

visualization.visualization.– lesions close to the chest wall may be more difficult to lesions close to the chest wall may be more difficult to

identify than lesions that are farther away. identify than lesions that are farther away. – A 30 posterior oblique image is recommended if lesions are A 30 posterior oblique image is recommended if lesions are

suspected close to the chest wall to increase the sensitivity suspected close to the chest wall to increase the sensitivity of finding the lesionof finding the lesion

• False-positive findings may occur with benign False-positive findings may occur with benign hypercellular lesions, inflammation, recent surgery, or hypercellular lesions, inflammation, recent surgery, or biopsy.biopsy.

30 posterior oblique

Right lateral static


SHUNT STUDYSHUNT STUDYCardiacCardiac

• The cardiovascular system may be divided into The cardiovascular system may be divided into right and left systems. right and left systems. – Right system consists of the venous system returning Right system consists of the venous system returning

deoxygenated blood to the heart, the right side of the deoxygenated blood to the heart, the right side of the heart, and the pulmonary arteries delivering blood to the heart, and the pulmonary arteries delivering blood to the lungs for gas exchange.lungs for gas exchange.

– Left system consists of the pulmonary veins returning Left system consists of the pulmonary veins returning oxygenated blood to the heart, the left side of the heart, oxygenated blood to the heart, the left side of the heart, and the systemic arterial system delivering blood to the and the systemic arterial system delivering blood to the body. body.

• Normally no significant crossover between the Normally no significant crossover between the systems occurs.systems occurs.

• A variety of conditions can result in abnormal A variety of conditions can result in abnormal communication between the 2 systems, resulting in communication between the 2 systems, resulting in mixing of blood.mixing of blood.


R-L SHUNT STUDYR-L SHUNT STUDY

• In R-L shunts, deoxygenated blood In R-L shunts, deoxygenated blood crosses into the left system, diluting crosses into the left system, diluting the oxygenation being delivered to the oxygenation being delivered to the systemic tissues and resulting in the systemic tissues and resulting in hypoxia.hypoxia.


R-L SHUNT STUDYR-L SHUNT STUDY

• R-L shunts may arise fromR-L shunts may arise from– Pulmonary arterial-venous Pulmonary arterial-venous

malformations in the lungsmalformations in the lungs• allow the incoming deoxygenated blood to allow the incoming deoxygenated blood to

bypass the capillary bed and pass into the bypass the capillary bed and pass into the left system without becoming oxygenated.left system without becoming oxygenated.

• a ventricular septal defect (VSD).a ventricular septal defect (VSD).– However these usually result in an L-R shunt However these usually result in an L-R shunt

because of the higher left-sided pressures. Under because of the higher left-sided pressures. Under chronic conditions right-sided heart pressures chronic conditions right-sided heart pressures often increase and may eventually even exceed often increase and may eventually even exceed left-sided pressures, causing a reversal of flow left-sided pressures, causing a reversal of flow and an R-L shunt.and an R-L shunt.


R-L SHUNT STUDYR-L SHUNT STUDYprocedure 1procedure 1

• Intravenous injection of 99mTc-Intravenous injection of 99mTc-MAAMAA– These particles are efficiently These particles are efficiently

trapped by the pulmonary trapped by the pulmonary capillariescapillaries

– The presence of an R-L shunt The presence of an R-L shunt results in greater activity results in greater activity appearing within the systemic appearing within the systemic organs.organs.

– Can be quantitated e.g. % R-L Can be quantitated e.g. % R-L ShuntShunt

= WB counts – Lung Counts / WB = WB counts – Lung Counts / WB counts X 100counts X 100

• Because the injection of 99mTc-Because the injection of 99mTc-MAA particles in the setting of MAA particles in the setting of an R-L shunt carries the an R-L shunt carries the theoretic risk of causing theoretic risk of causing microemboli in the brain and microemboli in the brain and other critical organs, it is other critical organs, it is recommended to reduce the recommended to reduce the number of particles to 10,000.number of particles to 10,000. R-L shunt = 41%.


R-L SHUNT STUDYR-L SHUNT STUDYprocedure 2procedure 2

• A first-pass approach is more A first-pass approach is more commonly used in the evaluation of commonly used in the evaluation of L-R shunts.L-R shunts.

• The primary ROI is the left ventricle The primary ROI is the left ventricle rather than the lungs, as an R-L rather than the lungs, as an R-L shunt will result in early appearance shunt will result in early appearance of activity within the left ventricle.of activity within the left ventricle.


L-R SHUNT STUDYL-R SHUNT STUDY• Shunts from the left system to the right system are Shunts from the left system to the right system are

frequently intracardiac - a defect in the septum frequently intracardiac - a defect in the septum allowing communication between the two sides of the allowing communication between the two sides of the heart exists.heart exists.– These may be between the 2 ventricles (ventricular septal These may be between the 2 ventricles (ventricular septal

defect)defect)– or between the 2 atria (atrial septal defect)or between the 2 atria (atrial septal defect)

• The shunt results in already-oxygenated blood passing The shunt results in already-oxygenated blood passing into the right heart and back to the lungs.into the right heart and back to the lungs.– cardiac output from the left side of the heart must increase to cardiac output from the left side of the heart must increase to

maintain normal forward flow through the aortamaintain normal forward flow through the aorta– Cardiac output from the right side of the heart is also Cardiac output from the right side of the heart is also

increased, as it must pump out both the normal volume of increased, as it must pump out both the normal volume of blood returning from the body plus the volume being shunted blood returning from the body plus the volume being shunted from the left heart.from the left heart.

• These effects can lead to elevated pulmonary pressures These effects can lead to elevated pulmonary pressures and heart failure.and heart failure.


L-R SHUNT STUDYL-R SHUNT STUDY• Assessment of an Assessment of an

R-L shunt uses a R-L shunt uses a firstpass analysis firstpass analysis technique, in technique, in which a bolus of which a bolus of radiopharmaceuticradiopharmaceutical is tracked using al is tracked using rapid dynamic rapid dynamic imaging through imaging through the heart and the heart and lungs. lungs.

• The study is The study is predicated on predicated on demonstrating demonstrating early return of early return of activity to the activity to the lungs after the lungs after the initial flow there.initial flow there.

normal L-R shunt study.


L-R SHUNT STUDYL-R SHUNT STUDYtechniquetechnique

• 99mTc-pertechnetate is most commonly used.99mTc-pertechnetate is most commonly used.• Dose is 7.4 MBq/kg (0.2 mCi/kg) with a minima and Dose is 7.4 MBq/kg (0.2 mCi/kg) with a minima and

maxima of 74 MBq (2 mCi) and 740 MBq (20 mCi), maxima of 74 MBq (2 mCi) and 740 MBq (20 mCi), respectively.respectively.

• A small volume such as 0.2 mL is necessary to help ensure A small volume such as 0.2 mL is necessary to help ensure a rapid, tight bolus injection.a rapid, tight bolus injection.– To help maintain the bolus, the injection should occur at a site To help maintain the bolus, the injection should occur at a site

with minimal distance to the right side of the heart. with minimal distance to the right side of the heart. • In theory, the right external jugular vein is best suited, but for In theory, the right external jugular vein is best suited, but for

practical purposes an antecubital vein is often substituted.practical purposes an antecubital vein is often substituted.– An intravenous or butterfly catheter is used.An intravenous or butterfly catheter is used.– A rapid injection of the radiopharmaceutical is made with a A rapid injection of the radiopharmaceutical is made with a

bolus of saline administered directly after the bolus of saline administered directly after the radiopharmaceutical injection.radiopharmaceutical injection.

• The dynamic acquisition is begun coincident with, or even The dynamic acquisition is begun coincident with, or even slightly before, the radiopharmaceutical injection.slightly before, the radiopharmaceutical injection.

• Dynamic imaging is obtained at 2–4 frames/s for 25 s using Dynamic imaging is obtained at 2–4 frames/s for 25 s using a 128 · 128 matrix, and LEHR Parallel hole collimator.a 128 · 128 matrix, and LEHR Parallel hole collimator.

J Nucl Med Technol 2008; 36:132–143

L-R SHUNT STUDYL-R SHUNT STUDYtechniquetechnique

• For the shunt analysis, an For the shunt analysis, an ROI is placed over each ROI is placed over each lung.lung.

• The lung activity is plotted The lung activity is plotted as a function of time.as a function of time.

• In the setting of an L-R In the setting of an L-R shunt, there will be shunt, there will be recirculation of recirculation of radiolabeled blood radiolabeled blood through the right heart through the right heart and onward to the lungs and onward to the lungs shortly after the initial shortly after the initial bolus passes through the bolus passes through the lungs, long before the lungs, long before the return of blood from the return of blood from the body.body.

Frank P. Dawry

normal L-R shunt study

L-R shunt


HEAT-DAMAGED RBC HEAT-DAMAGED RBC STUDYSTUDY

• One of the functions of the spleen is removal One of the functions of the spleen is removal of damaged and obsolescent blood cells.of damaged and obsolescent blood cells.

• Normal RBCs are deformable and pass Normal RBCs are deformable and pass readily through the spleen readily through the spleen

• Heat-damaged, or heat-denatured, RBCs Heat-damaged, or heat-denatured, RBCs undergo fragmentation and spherocytosis, undergo fragmentation and spherocytosis, leading to increased stiffness and, leading to increased stiffness and, consequently, entrapment by the spleenconsequently, entrapment by the spleen

• Heat-damaged RBC study a sensitive and Heat-damaged RBC study a sensitive and specific method of identifying splenic tissue.specific method of identifying splenic tissue.



indicationsindications• The main indications for this study are The main indications for this study are

– to identify accessory splenic tissue (also to identify accessory splenic tissue (also known as splenules) after surgical known as splenules) after surgical splenectomy for thrombocytopenia (low splenectomy for thrombocytopenia (low platelets)platelets)

– identify accessory splenic tissue after splenic identify accessory splenic tissue after splenic traumatrauma

– assess whether a mass found on anatomic assess whether a mass found on anatomic imaging, such as CT, is a splenule.imaging, such as CT, is a splenule.

– and assess congenital abnormalities of and assess congenital abnormalities of splenic number (asplenia or polysplenia) or splenic number (asplenia or polysplenia) or splenic location (wandering spleen).splenic location (wandering spleen).



procedureprocedure• in vitro labeling of the patient’s RBCs with in vitro labeling of the patient’s RBCs with

37–111 MBq (1–3 mCi) of 99mTc 37–111 MBq (1–3 mCi) of 99mTc pertechnetate.pertechnetate.

• The labeled RBCs are then heated in a water The labeled RBCs are then heated in a water bath at 49.5C 6 0.5C for 20 minbath at 49.5C 6 0.5C for 20 min– Maintaining the specified temperature Maintaining the specified temperature

throughout the heating process is critical.throughout the heating process is critical.• Overheating will lead to excessive damage of the RBCs, Overheating will lead to excessive damage of the RBCs,

resulting in increased uptake by the liver and decreased resulting in increased uptake by the liver and decreased uptake by splenic tissue.uptake by splenic tissue.

• Conversely, underheating will lead to insufficient Conversely, underheating will lead to insufficient damage of the RBCs, also leading to decreased splenic damage of the RBCs, also leading to decreased splenic uptake, along with increased activity in the circulating uptake, along with increased activity in the circulating blood pool.blood pool.


Spleen ImagingSpleen Imaging

• 99mTc sulfur colloid may be used to 99mTc sulfur colloid may be used to assess splenic tissue. assess splenic tissue.

• However, the colloid is also taken up However, the colloid is also taken up by the liver and bone marrow, and by the liver and bone marrow, and consequently this test is less sensitive consequently this test is less sensitive and specific. and specific.

• The normal spleen takes up only about The normal spleen takes up only about 10% of injected 99mTc-sulfur colloid, 10% of injected 99mTc-sulfur colloid, versus 90% of heat damaged RBCs.versus 90% of heat damaged RBCs.

J Nucl Med Technol 2008; 36:132–143


procedure continuedprocedure continued• Imaging can begin Imaging can begin

30 min after 30 min after injection.injection.

• Planar and SPECT Planar and SPECT scans should be scans should be performed. performed.

• When the study is a When the study is a search for accessory search for accessory splenic tissue, the splenic tissue, the entire abdomen entire abdomen must be imaged.must be imaged.

Frank P. Dawry

frank p. dawry infrequently performed studies in nuclear medicine j nucl med technol 2008;...

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