abdomen and pelvic hybrid imaging: anatomy, variants, urgent
TRANSCRIPT
Abdomen and Pelvic Hybrid
Imaging: Anatomy, Variants,
Urgent Findings David M Schuster, MD with special thanks to
Deb Baumgarten, MD and Courtney Moreno, MD
You are reading a PET-CT for lung
cancer and see this…
Or this…
Is it abnormal?
And what is it?
First review:
Slice by Slice
Correlative Anatomy
Esophagus Aorta
Liver
Esophagus
Esophagus Aorta
Latissimus dorsi
Serratus anterior
Spleen
Stomach
Liver EG junction
colon: splenic flexure
7
8
4a 2
7=posterior, right
(right hepatic vein)
8=anterior, right
(middle hepatic vein)
4a=medial, left
(left hepatic vein)
2=lateral, left
Aorta
Stomach Colon
Spleen Splenic vessels
Fissure for ligamentum venosum Caudate lobe
Pancreas
6
5
4b 3
6=posterior, right
(approximate)
5=anterior, right
(gallbladder)
4b=medial, left
(falciform fissure)
3=lateral, left
Fissure for
ligamentum teres
Adrenals
Hepatic Segments
Aorta IVC Portal vein
Splenic artery
and vein
GB Adrenals
Pancreas
Celiac axis
Colon
Superior
kidneys
Crura of diaphragm
Aorta SMA
origin
Duodenum
Left renal vein crossing
over aorta, not
duodenum
IVC
SMA SMV
Kidneys at hila Right renal vein
Aorta
Colon
Latissimus Serratus posterior
Psoas muscles
Colon
Colon
Small bowel loops (jejunum)
IVC Aorta
a
Inferior
kidneys
Aorta
Small
bowel
loops
3rd portion of duodenum
Colon
Aorta IVC
External oblique Internal oblique
Transverse
abdominus
Rectus abdominis
Ureters
Psoas muscles
Small bowel
loops
Aorta IVC
Colon
Aortic bifuraction
Psoas muscles
Small
bowel
loops
Small bowel
loops
Colon
IVC
bifurcation
Psoas muscles
Ileocecal valve
Common iliac vessels
Small bowel
loops
Psoas muscles
Small bowel loops
Colon
Iliacus muscle
Psoas muscles
Small bowel
loops
Colon Appendix
Ilium Sacrum
Small bowel
loops
Iliacus muscle
External iliac
vessels
Internal iliac
vessels
Gluteus maximus
Gluteus medius
Gluteus minimus
Focal
ureteral
activity
Iliopsoas
muscle
Small bowel
loops
Small bowel
loops
Colon
Sigmoid
colon
Small bowel
loops
Piriformis
Rectum
Ureters inserting into
trigones
Bladder
Seminal
vessicles
Ischium
Obturator
internus
Prostate
Pectineus Obturator
externus Obturator internus
Pectineus Obturator
externus Obturator internus
Pectineus Obturator
externus Obturator internus
Ischial
tuberosity
Anus Penile crura
Testicles
Abdominal Misregistration
Colon projected into liver
Normal Uptake and Variants-
GI Tract
• Widely variable – Must distinguish from pathology
– Usually contiguous but may also be focal
• can also be polyp, cancer
– IBD can also cause false positive uptake
• PET-CT invaluable
• GE junction common – Probably related to LES
GI Tract
• Stomach – Usually mild, diffuse
– More common and intense at fundus
– Can be focal, especially if contracted
– Hiatal hernia
– Intense and focal or distal evaluate
– CT abnormality evaluate
GI Tract
• Small Bowel and Large Bowel – Usually lower intensity and contiguous
– Can be focal
• Especially right colon – Smooth muscle
– Active mucosa
– Lymphoid tissue
– Secretions and microbe flora
Colon and Small Bowel
• Focal or segmental – More intense than liver
• Worry about tumor
– Most will be benign
• CT correlation can be helpful
• IBD/diverticulitis/inflammation
• Colitis – Post-chemotherapy
Prabhakar et al. Radiographics 2007;27:145
Normal Uptake and Variants -
Esophageal
EG
junction
Normal Uptake and Variants -
Esophageal
Hiatal hernia
Normal
stomach
Normal Uptake and Variants - Stomach
Normal Uptake and Variants – Small Bowel
Small bowel
uptake but no
colon
Small bowel
uptake
Normal Uptake and Variants - Colon
Colon Polyp
Liver • Liver
– Normal heterogeneity
– Respiratory artifact
Normal Uptake and Variants – GB
• Physiologic accumulation infrequent normal variant – Murata et al. Nucl Med Biol 2007;34:961
• But uptake in wall – Cholecystitis
– Possibly tumor, especially focal
Adrenal
• No uptake or less than liver is good
• Watch out for necrosis
• Combine appearance on PET with CT
• Intense uptake malignant
Adrenal
• Bilateral adrenal
masses
• Right: low
density
adenoma
• Left adrenal
cancer
Mild uptake left adrenal
low density nodule or
hyperplasia with SUV
of 1.7 and HU of 1.4,
stable on f/u CT 6
months later
Normal Uptake and Variants - Adrenals
72 year old male
lung cancer
MIBG SPECT/CT: Pheochromocytoma
Solid right
adrenal mass
seen well on
CT and
intense on
MIBG
Normal Uptake and Variants – Renal
• Renal excretion of FDG. – Unlike glucose, FDG not well reabsorbed by
tubular cells of the kidney
– Well hydration to wash out renal excretion
– Some advocate lasix
– Patient supine so radiotracer pools in upper collecting system
– Also look for diverticula, communicating cysts, redundant and duplicated ureters
Renal Cyst
Simple cysts should be photopenic
Normal Uptake and Variants – Urinary
• Ureter usually linear, easily identifiable
• Focal ureter activity may look like lymph node but CT fusion helps
• Bladder usually intense but doesn’t obscure with iterative reconstruction
• Look for diverticula, nodules, TURP
• Some advocate foley
• Vesselle HJ. Miraldi FD. FDG PET of the retroperitoneum: normal
anatomy, variants, pathologic conditions, and strategies to avoid diagnostic pitfalls. Radiographics. 18(4):805-24; 1998 Jul-Aug.
Duplicated Right Ureter
Bifid ureter, not adjacent
lymph node
Normal Uptake and Variants – Renal
Use other imaging planes...
Normal Uptake and Variants – Renal
Duplex system on the right
Normal Uptake and Variants – Renal
Focal ureter crossing over iliac vessels, no lymph node
Normal Uptake and Variants – Bladder
Bladder
Even with iterative
reconstruction,
may still cause
some artifact
Normal Uptake and Variants
Bladder Diverticulum
Normal Uptake and Variants – Brown Fat
Brown fat may
be around
diaphragm
and even peri-
renal
Normal Uptake and Variants – Uterine
• Low level uptake is common, but can increase with menses.
• Lerman H, et al. Normal and abnormal 18F-FDG endometrial and ovarian uptake in pre- and postmenopausal patients: assessment by PET/CT. Journal of Nuclear Medicine. 45(2):266-71, 2004 Feb.
– CONCLUSION: In premenopausal patients, normal endometrial uptake of (18)F-FDG changes cyclically, increasing during the ovulatory and menstrual phases. Increased uptake in the endometrium adjacent to a cervical tumor does not necessarily reflect endometrial tumor invasion. Increased ovarian uptake in postmenopausal patients is associated with malignancy, whereas increased ovarian uptake may be functional in premenopausal patients.
Normal Uptake and Variants – Uterine
Uterus with slightly hotter stripe at endometrium Mild ovarian
uptake
Bladder
Young female with benign mediastinal mass
Normal Uptake and Variants – Uterine
Uptake in vagina is not cancer but tampon.
Premenopausal uptake in fibroid
may be intense
Normal Uptake and Variants – Ovarian • Increased unilateral uptake with ovulation (may be bilateral)
• Also look at morphology of ovaries. May need followup.
• Fenchel S, et al. Asymptomatic adnexal masses: correlation of FDG
PET and histopathologic findings. Radiology. 223(3):780-8, 2002 Jun.
– PET positive with 7/12 malignant tumors
– Uptake, even intense, with benign disease at times
• Corpus luteum cysts
• Other benign tumors and inflammation
Normal mild uptake in ovaries
Gastric Cancer
Krukenberg
tumors: Bilateral
uptake, post-
menopausal,
complex appearing
ovaries
Normal Uptake and Variants – Testes
• Normal and decreases with aging – Kosuda S, et al. Uptake of 2-deoxy-2-[18F]fluoro-D-
glucose in the normal testis: retrospective PET study and animal experiment. Annals of Nuclear Medicine. 11(3):195-9, 1997 Aug.
• If see unilateral or very intense, investigate further
Normal Uptake and Variants – Testes
Remember: CT Adds Other Information
• Kamel, et al. Incremental Value of CT in Combined
PET/CT for the Evaluation of Patients with Colorectal
Carcinoma: Initial Experience. Radiology 225 (p):424
– 59 cases
– In 10 patients, CT provided important information which
impacted interpretation
– Also found 15 incidental findings such as renal and
gallstones, etc.
6cm AAA and horseshoe kidney
Pick up the phone…
and you see this…
Ruptured AAA Normal
Aortic Dissection
Pneumoperitoneum
Free air anterior to liver
Small foci of air outside bowel lumen
Pneumoperitoneum
Use Lung Windows to Help
Pneumoperitoneum: Use Other Planes
Pneumatosis and Pneumobilia
Small Bowel Obstruction Due
to Ventral Hernia
Persistent Abdominal Pain in Post-Colon Cancer
Despite Treatment for Recent “UTI”
Appendicitis on Surgery
Acute Appendicitis Normal
Crohn Disease
(DDX infection, inflammation,
ischemia)
Normal
Diverticulitis
Cholecystitis
Ruptured Diaphragm: GB Points Up
Emphysematous
Cholecystitis Normal
Emphysematous Cystitis
Pancreatitis Normal
Pancreatitis
Ascites
Ascites on Liver/Spleen Scan
But Remember This Appearance:
Omental Caking
New Mild Hydronephrosis
New Mild Hydronephrosis
Stone in ureter
Right ureterovesical
junction stone
Left ureteral
stone
Don’t Confuse Pelvic Kidney with Tumor
Knowing CT is Important:
Not All Cancer is Hot
Mucinous
Adenocarcinoma
Recurrence
The End….
Stay tuned for MSK…