ct imaging of the kidney - lieberman's eradiology
TRANSCRIPT
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Anthony PowellGillian Lieberman, MD
CT Imaging of the Kidney
Anthony Powell, HMS IVBeth Israel Deaconess Medical Center
Gillian Lieberman, MD
Images: BIDMC, Dept of Radiology, 2001.
September 2001
Images: Netter, FH: Atlas of Human Anatomy, 2nd ed. Novartis, 1997
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Anthony PowellGillian Lieberman, MD
Renal Anatomy: Axial View
Gerota’s FasciaPerinephric fat
Pararenal fat
Peritoneum Right Kidney
Renal Capsule
Renal Artery
Renal Vein
Images: Netter, FH: Atlas of Human Anatomy, 2nd ed. Novartis, 1997
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Anthony PowellGillian Lieberman, MD
Renal Anatomy: Sagittal View
Minor Calices
Renal Pelvis
Major Calices
Renal Column (of Bertin)
Renal Pyramids
Renal Cortex
Ureter
Images: Netter, FH: Atlas of Human Anatomy, 2nd ed. Novartis, 1997
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Anthony PowellGillian Lieberman, MD
Standard CT Technique for Renal Imaging
• 5mm-10mm collimation usually adequate to demonstrate kidneys
• IV contrast allows differentiation of pathologic processes from nl parenchyma– Corticomedullary differentiation max at 30 sec– Nephrographic phase best seen at 70-100 sec
• Non-contrast Helical CT for uro/nephrolithiasis
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Anthony PowellGillian Lieberman, MD
Congenital Abnormalities
• Duplicated collecting system/partial duplication bifid renal pelvis
• Horseshoe Kidney– Connecting isthmus across midline, usu between lower poles
• Crossed Ectopia– The ureter of the ectopic kidney inserts into the bladder
orthotopically (I.e. on opposite side)
• Pelvic or Intrathoracic Kidney• Renal hypoplasia• Renal agenesis
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Anthony PowellGillian Lieberman, MD
Crossed Ectopia
• Lower kidney is usually the ectopic one
• In 90% there is fusion of both kidneys (crossed- fused ectopia)
• Incidence 1:1000 births
• Slightly increased incidence of calculi, however, incidence of other assoc anomalies is low
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Anthony PowellGillian Lieberman, MD
Crossed Ectopia
Images: BIDMC, Dept of Radiology, 2001.
Axial abdominal CT, contrast enhanced, nehrogram phase
Right orthotopic kidney
Left crossed ectopic kidney
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Anthony PowellGillian Lieberman, MD
NephrocalcinosisCauses:• Renal Artery Atherosclerosis• Nephrolithiasis= stones in the collecting system
• Medullary Nephrocalcinosis (95%)= calcium deposition in medulla– Renal Tubular Acidosis, Medullary Sponge Kidney, HyperCa2+
states (hyperPTH, Paraneoplastic), Papillary necrosis (Diabetes Mellitus, sickle cell), TB
• Cortical Nephrocalcinosis (5%)= calcium deposition in cortex– Chronic poststrep glomerulonephritis, Oxalosis, Alport synd,
Acute cortical necrosis
• Infection, Cyst, Tumor, Hematoma
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Anthony PowellGillian Lieberman, MD
Nephrolithiasis
• Epidemiology– Up to 10% by age 70, usu in 3rd to 4th decade– 4:1 M to F ratio– More prevalent in the South
• Risk Factors– Hypercalcemic states, Crohn’s, stents, RTA, infection,
gout, hypercalciuria, hyperuricosuria, cystinuria
• Symptoms– Asymptomatic, flank pain, hematuria
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Anthony PowellGillian Lieberman, MD
CompositionOPAQUE contains calcium +/ phosphate• Calcium calculi
– Ca oxalate, Ca phosphate
• Struvite calculi– Magnesium ammonium phosphate= triple phosphate
SEMI OPAQUE contains sulphur• Cystine calculiLUCENT• Uric acid stones;Xanthine• Matrix (coagulated mucoid material)
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Anthony PowellGillian Lieberman, MD
CT Imaging of Stones
• Essentially all renal and ureteral calculi have high attenuation on non-contrast CT (all but matrix stones have atten of > 100HU)
• CT has sensitivity of 97% and specificity of 96%• Can also see hydronephrosis, hydroureter, renal
enlargement, or perirenal stranding• Must differentiate from phlebolith which is a
calcified blood clot in a pelvic vein.(appearance: round/ovoid, smooth, central lucency, in true pelvis)
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Anthony PowellGillian Lieberman, MD
Nephrolithiasis
Images: BIDMC, Dept of Radiology, 2001.
Radio opaque stone in calyx
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Anthony PowellGillian Lieberman, MD
Hydronephrosis
Images: BIDMC, Dept of Radiology, 2001.
Dilated urine filled pelvis
Stent
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Anthony PowellGillian Lieberman, MD
Hydroureter
Images: BIDMC, Dept of Radiology, 2001.
Stent
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Anthony PowellGillian Lieberman, MD
Pyelonephritis
• Bacterial infection of portions of renal parenchyma
• Usually via ascending infection from the bladder• Risk Factors include vesicoureteral reflux, DM,
pregnancy, immunocompromised states, prolonged catheterization, neurogenic bladder
• Sx’s include flank pain, fever, pyuria, leukocytosis• Usual suspects E. coli, proteus, klebsiella
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Anthony PowellGillian Lieberman, MD
CT Imaging of Pyelonephritis
• Focal or diffuse renal enlargement• Parenchyma may be low in attenuation on non-
contrast (C-) images• Usually wedge-shaped regions of decreased
enhancement on C+ images• Perinephric stranding or fluid collections, often w/
thickening of Gerota’s fascia
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Anthony PowellGillian Lieberman, MD
Pyelonephritis
Images: BIDMC, Dept of Radiology, 2001.
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Anthony PowellGillian Lieberman, MD
Xanthogranulomatous Pyelonephritis (XGP)
• Bacterial renal infection with an unusual/characteristic immune response
• Parenchyma infiltrated with lipid-laden macrophages
• Proteus mirabilis is usual causative organism• Associated with staghorn calculus• Often chronic, non-spec sx’s fever, malaise,
pain, leukocytosis
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Anthony PowellGillian Lieberman, MD
CT Characteristics of XGP
• May demonstrate classic finding of staghorn calculus
• Low-attenuation renal mass; decreased excretion of contrast
• Enlarged kidney• Perinephric inflammatory changes• 85% of cases have diffuse renal involvement
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Anthony PowellGillian Lieberman, MD
Xanthogranulomatous Pyelonephritis
Images: BIDMC, Dept of Radiology, 2001.
Perirephric inflammatory change
Sephern calcubus
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Anthony PowellGillian Lieberman, MD
XGP with Staghorn Calculus
Images: BIDMC, Dept of Radiology, 2001.
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Anthony PowellGillian Lieberman, MD
Perinephric Stranding from XGP
Images: BIDMC, Dept of Radiology, 2001.
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Anthony PowellGillian Lieberman, MD
Renal Cystic Disease
• Very common 50% of pts over age of 50• Assoc w/ many syndromes, etiology unknown,
probably arise from obstructed tubules or ducts• Most commonly asymptomatic• Rarely, may have hematuria, HTN, cyst infection,
or mass effect
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Anthony PowellGillian Lieberman, MD
CT Characteristics of Simple Cysts
• Smooth, imperceptible cyst wall• Sharp demarcation from surrounding renal
parenchyma• Water attenuation (<15 HU), homogenous
throughout lesion• Non-enhancing• Simple cysts are w/o septations or calcification• May have slight elevation of adjacent renal
parenchyma Beak sign
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Anthony PowellGillian Lieberman, MD
Complex Cysts: Categorized using the Bosniak Classification• Categories based on imaging features that are
intended to serve as guideline for estimating likelihood of malignancyType I- simple cystType II- mildly complicated cyst mild Ca2+, thin
septations, no enhancementIIF- slightly more complex type II lesions
Type III- complex cysts thick wall; multiple, irreg, thick septations/calcifications, no enhancement
Type IV- cystic neoplasm enhancing wall or solid component
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Anthony PowellGillian Lieberman, MD
Treatment
• Type I – no f/u required• Type II – no f/u required• Type IIF – f/u CT after 3-6 months• Type III – Excision• Type IV - Excision
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Anthony PowellGillian Lieberman, MD
Type I Simple CystBird Beak
Sign
Images: BIDMC, Dept of Radiology, 2001.
Simple Cyst
Aortic aneurysm
Inferior vena cava with filters
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Anthony PowellGillian Lieberman, MD
Type IV Cystic Neoplasm
Images: BIDMC, Dept of Radiology, 2001.
Complex renal mass infiltrating lvc
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Anthony PowellGillian Lieberman, MD
Conditions Associated with Multiple Cysts
• Autosomal Dominant PCKD• Autosomal Recessive PCKD• Acquired Cystic Disease (hemodialysis pts)• Von-Hippel-Lindau disease• Tuberous Sclerosis• Medullary Sponge Kidney
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Anthony PowellGillian Lieberman, MD
Benign Masses
• Cysts• Angiomyolipoma• Oncocytoma (via epithelial cells of prox tubule)• Renal Adenoma • Mesoblastic Nephroma (hamartomatous tumor,
usu present at birth)• Hemangioma• Various Renal Pelvic Tumors(papilloma, angioma,
fibroma)• Hematoma
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Anthony PowellGillian Lieberman, MD
Angiomyolipoma
• Hamartomas containing fat, smooth muscle, and blood vessels
• Usually asymptomatic, but may spontaneously bleed
• Large AMLs resected or embolized• Multiple AMLS usually Associated w/ tuberous
sclerosis• On CT *fat attenuation in mass*, strong
contrast enhancement (RCCs rarely contain fat), no Ca2+
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Anthony PowellGillian Lieberman, MD
Angiomyolipoma
Images: BIDMC, Dept of Radiology, 2001.
Note fat content
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Anthony PowellGillian Lieberman, MD
Malignant Masses
• Renal Cell Cancer• Transitional Cell Cancer• Wilm’s Tumor • Nephroblastomatosis (multiple rests of
embryologic metanephric blastoma)• Lymphoma• Metastases (lung, breast, colon, melanoma)
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Anthony PowellGillian Lieberman, MD
Renal Cell Ca
• Most common primary renal malignancy (85% of primary renal tumors)
• Assoc w/ smoking, family hx, age, Von Hippel- Lindau, Acquired Cystic Disease/chronic dialysis, phenacetin abuse
• Presentation: Hematuria, flank pain, wt loss, palp mass, fever, anemia, paraneoplastic syndromes
• liver enzymes w/o mets Stauffer syndrome
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Anthony PowellGillian Lieberman, MD
CT characteristics
• Variable from complex cyst to large, heterogeneous renal mass
• Generally enhancing• May have calcifications• May have hemorrhage and central necrosis• Usually no fat
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Anthony PowellGillian Lieberman, MD
Robson Staging
• Stage I – contained w/in renal capsule• Stage II – contained w/in Gerota’s fascia• Stage III
A – venous invasion (renal v, IVC)B – lymphatic invasion C – both
• Stage IV – distant metastasis (lungs, liver, lytic bone, adrenal, contra renal)
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Anthony PowellGillian Lieberman, MD
Renal Cell Ca
Images: BIDMC, Dept of Radiology, 2001.
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Anthony PowellGillian Lieberman, MD
RCC
Images: BIDMC, Dept of Radiology, 2001.
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Anthony PowellGillian Lieberman, MD
References• Netter, FH: Atlas of Human Anatomy, 2nd ed. Novartis, 1997• Slone RM, Fisher AJ, Pickhardt PJ, Gutierrez FR, Balfe DM: Body
CT, A Practical Approach, 1st ed. McGraw-Hill, 2000• Weissleder R, Rieumont MJ, Wittenberg J: Primer of Diagnostic
Imaging, 2nd ed. Mosby, 1997• Beth Israel Deaconess Medical Center, Dept of Radiology, Teaching
Files, 2001• Gay SB, Woodcock RJ: Radiology Recall, 1st ed. Lippincott Williams
and Wilkins, 2000
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Anthony PowellGillian Lieberman, MD
Acknowledgements
• Pamela Lepkowski• Gillian Lieberman M.D.• Richard Cooper M.D.• Joe Barry M.D.• Mary Keogan M.D.