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Focal renal FDG uptake H. Adams

Focal renal fdg uptake

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Page 1: Focal renal fdg uptake

Focal renal FDG uptake

H. Adams

Page 2: Focal renal fdg uptake

Gross anatomy

The Renal System Explained. Deshmukh. Nottingham University Press 2009

Renal column

Major calyx

Minor calyx

Page 3: Focal renal fdg uptake

Transverse section

Page 4: Focal renal fdg uptake

Incidental focal renal FDG uptake

Page 5: Focal renal fdg uptake

FDG PET:Primary detection of RCC

Ceyssens, Mortelmans. Positron Emission Tomography in Renal Cancer. 2008, Renal Cell Cancer, Pages 131-136

N

9053

1710

Not highly effective for primary diagnosis. Studies with PET standalone, not PET-CT. Difficulties with urinary excretion. Inconsistencies depending on cell differentiation.Very high specificity!

Page 6: Focal renal fdg uptake

Incidental focal renal FDG uptakeDifferential

• Benign:– Pyelum– Calyceal Diverticulum – (adrenocortical) Oncocytoma– Infected cyst / Abcess / hematoma– xantogranulomatous pyelonephritis– Angiomyolipoma

• Malignant:

– (cystic) Renal Cell Carcinoma (RCC)– transitional cell carcinoma (TCC)– Renal lymphoma– Metastasis

If low dose CT not sufficient, then contrast enhanced (diagnostic) CT

Additional strategies

Page 7: Focal renal fdg uptake

Imaging the Solid Renal Mass in AdultsCT: strategies

Ball versus the Bean

Visible onUnenhanced CT

+Enhanced CT

Not visible onUnenhanced CT

Page 8: Focal renal fdg uptake

Ball versus the Bean

PET +

PET +

PET +

PET +

PET +

PET +PET +

PET - ?

PET - ?

PET +

Page 9: Focal renal fdg uptake

Balltype RCC on CTUnenhanced CT + Enhanced CT

renal hump at unenhanced CT well-defined ball-type lesion

Radiology: Volume 247: Number 2—May 2008

Page 10: Focal renal fdg uptake

RCCs in context of acquired cystic disease

Unenhanced CT + Enhanced CT

numerous masses bilaterally in atrophickidneys. Calcification (arrowhead) is seen in cyst

well-defined ball-type lesion: 2-cm enhancing mass: RCC

Page 11: Focal renal fdg uptake

RCC on CTEnhanced CT: Improved mass conspicuity during nephrographic phase

Corticomedullary phase Nephrographic phase: RCC

Page 12: Focal renal fdg uptake

Bean type lesion: TCCTransitional cell carcinoma (TCC) / urothelial cell carcinoma

• Focal intraluminal mass in the renal collecting system

• Alters the regional architecture of renal sinus and parenchyma but preserves the renal contour.

Unenhanced CT: obliteration of the sinus fat in upper aspect of the right kidney

Page 13: Focal renal fdg uptake

Bean type lesion: TCC

Enhanced nephrographic-phase:poorly defined parenchymal masswith no alteration of the renal contour

Obliteration of caliceal elements inthe upper pole (phantom calyces

Page 14: Focal renal fdg uptake

Angiomyolipoma (AML) Lesions• Ball-type renal lesion contains detectable fat at CT imaging:

nearly specific diagnosis of AML• Fat: clustered pixels with negative CT numbers (defined as at

least 3 adjacent pixels with attenuation -20 HU or less)

1.3-cm lesion (arrow)Primarily fat (attenuation -66 HU)No further workup necessary

Page 15: Focal renal fdg uptake

Angiomyolipoma (AML) Lesions

Indeterminate mass: pixel mapping; internal attenuation 16 HU. Clusters of pixels < < -20 : Angiomyolipoma, but Follow up required.

Page 16: Focal renal fdg uptake

Multiple AMLs

Pt with Tuberous sclerosis: Near-total replacement of the right kidney by multiple fat-containing AMLsLeft kidney (K) also harbors numerous smaller but similar-appearing masses

Page 17: Focal renal fdg uptake

Ball type: Oncocytoma• RCC and oncocytoma can be indistinguishable, especially when the tumor

is small• May be quite large (up to 25 cm)• central stellate scar• Most commonly excised benign

Solid renal mass!

Stellate central scar (arrow). Presence of pseudocapsule at posterior margin of the mass.

Page 18: Focal renal fdg uptake

Renal metastases• Fifth most common site of hematogenous

metastases (4x more than RCCs)• Lung, breast, gastrointestinal tumors and melanoma

are the most common• Often as a part of widespread disease.

• Metastatic lesions are typically:

– small, multifocal, and bilateral,– exhibiting an infiltrative growth pattern.– The contrast enhancement is much less than that

of normal renal parenchyma

Page 19: Focal renal fdg uptake

Renal metastases

Two poorly defined bean-type lesions:squamous cell lung carcinoma

Extensive hepatic metastatic disease and abnormal retroperitoneal lymphadenopathy

Page 20: Focal renal fdg uptake

Renal lymphoma

large B-cell type non-Hodgkin lymphomaMultiple masses, incl. right kidney

Non-Hodgkin lymphoma: - bilateral Bean type lesions- Splenic lesions (arrow)

Page 21: Focal renal fdg uptake

Focal renal FDG uptakeDifferential

• Benign:– Pyelum low dose or CT– Calyceal Diverticulum low dose or CT– (adrenocortical) Oncocytoma CT or biopsy– Infected cyst / Abcess / hematoma– xantogranulomatous pyelonephritis– Angiomyolipoma low dose or CT

• Malignant:

– (cystic) Renal Cell Carcinoma (RCC) CT or biopsy– transitional cell carcinoma (TCC) CT or biopsy– Renal lymphoma CT in case clinically relevant– Metastasis CT in case clinically relevant

Page 22: Focal renal fdg uptake

Renal hematoma

Unenhanced CT: heterogeneouslyhyperattenuating (46 HU) renal mass(arrows) with calcifications

Enhanced CT scan during nephrographicPhase: no enhancement of the mass

Silverman et al. Hyperattenuating Renal Masses: Etiologies, Pathogenesis, and Imaging Evaluation. RG 2007

Page 23: Focal renal fdg uptake

Benign Hyperattenuating CystsBenign cysts are overwhelmingly the most common type of hyperattenuating renal mass. (Bosniak class.)

Unenhanced CT:Hyperattenuating (80 HU) renal mass

Contrast-enhanced CT:No enhancement of the mass.

Page 24: Focal renal fdg uptake

Other types of hyperattenuating renal masses

• Renal cell carcinoma• Angiomyolipoma with minimal fat• Multilocular cystic renal cell carcinoma

RCC: enhancement of the mass

Page 25: Focal renal fdg uptake
Page 26: Focal renal fdg uptake

hyperattenuating renal masses

• If PET positive:– CT, MRI and eventually biopsy can be needed– Ultrasound not modality of choice

Multilocular cystic renal cell carcinoma: enhancing septa

Page 27: Focal renal fdg uptake

Focal renal FDG uptakeDifferential

• Benign:– Pyelum low dose or CT– Calyceal Diverticulum low dose or CT– (adrenocortical) Oncocytoma CT or biopsy– Infected cyst / Abcess / hematoma low dose (if hyperattenuating: CT, MRI or

biopsy)– xantogranulomatous pyelonephritis

– Angiomyolipoma low dose or CT (if hyperattenuating: MRI) • Malignant:

– (cystic) Renal Cell Carcinoma (RCC) CT or biopsy (if hyperattenuating: MRI)– transitional cell carcinoma (TCC) CT or biopsy– Renal lymphoma CT in case clinically relevant– Metastasis CT in case clinically relevant

Page 28: Focal renal fdg uptake

Xanthogranulomatous pyelonephritis

• Rare inflammatory condition usually secondary to chronic obstruction

• Is associated with a staghorn calculus in approximately 70% of cases.

• Classic urographic triad:– unilaterally decreased or (more commonly) absent renal

excretion– a staghorn calculus– poorly defined mass or diffuse renal enlargement.

Page 29: Focal renal fdg uptake

Xanthogranulomatous pyelonephritis

right xanthogranulomatous pyelonephritis

Page 30: Focal renal fdg uptake

• Benign:

– Pyelum low dose or CT– Calyceal Diverticulum low dose or CT– (adrenocortical) Oncocytoma CT or biopsy– Infected cyst / Abcess / hematoma low dose (if hyperattenuating: CT,

MRI or biopsy)– xantogranulomatous pyelonephritis low dose or CT– Angiomyolipoma low dose or CT (if hyperattenuating: MRI)

• Malignant:

– (cystic) Renal Cell Carcinoma (RCC) CT or biopsy (if hyperattenuating: MRI)– transitional cell carcinoma (TCC) CT or biopsy– Renal lymphoma CT in case clinically relevant– Metastasis CT in case clinically relevant

Focal renal FDG uptakeDifferential

Page 31: Focal renal fdg uptake

Reference: PET• Positron Emission Tomography in Renal Cancer.pdf• PET and PETCT of Urological Malignancies An Update Review.pdf

CT/MRI• Simplified imaging approach for evaluation of the solid renal mass in adults Radiology 2008 331.pdf

• Hyperattanuating renal masses etiology pathogenesis and Imaging Evaluation Radiogr 2007 1131[1].pdf

Focal renal FDG uptakeDifferential