The Incidental Renal lesion

Transcription

1 The Incidental Renal lesion

2 BACKGROUND Increase in abdominal CT/US in last 15 years Resulted in detection of many (small) renal lesions 50% > 50yrs has at least 1 lesion majority simple cysts Renal lesions usually categorised as solid or cystic Some remain indeterminate

3 SPECTRUM Simple cyst Bosniak 2 AML (Oncocytoma) Benign Bosniak 4 RCC TCC Lymphoma Malignant Indeterminate Complex cyst 2F/3 Infection Haemorrhage Solid SRM s

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5 Questions What would be the consequence of NOT characterising incidental lesions? What would be the consequence of NOT following up incidental lesions? By size? By age/ co-morbidities?

6 Solid masses Size Enhancement Fat content Shape Surrounds History

7 Size Cysts No relationship with malignancy Solid : Frank et al J Urol 2003; 170: Reviewed 2770 resected tumours; benign in: 25% < 3cm 30% < 2cm 44% < 1cm Jeon et al Urology 2010; 81/376 masses <4cm benign (21%)

8 Bosniak Classification 1 Simple cyst with a hairline-thin wall that does not enhance. Water attenuation. (-10 to + 20 HU) 2 May contain a few hairline-thin septa. Fine or slightly thickened calcification Sharply marginated uniformly high-attenuating lesions (<3 cm) that do not enhance. 2F May contain multiple hairline-thin septa with perceived enhancement. Minimal thickening of the wall or septa calcification may be thick or nodular No measurable contrast enhancement. 3 Cystic mass with thickened irregular or smooth walls or septa, in which measurable enhancement is present at CT, MRI or CEUS. 4 Clearly malignant cystic masses that can have all of the criteria of category III, but also contain distinct enhancing soft-tissue nodules

9 Bosniak Classification 2F May contain multiple hairline-thin septa with perceived enhancement. Minimal thickening of the wall or septa calcification may be thick or nodular No measurable contrast enhancement. OBSERVE 2-5 YEARS 3 Cystic mass with thickened irregular or smooth walls or septa, in which measurable enhancement is present at CT, MRI or CEUS. REMOVE /ABLATE

10 ULTRASOUND Minimally complex cysts (BOSNIAK 2) Few hairline septa Acoustic enhancement Calcification acoustic shadowing. Requires CT

11 ULTRASOUND Complex cysts: (BOSNIAK 2F 4) Thickened septa Solid elements Flow on colour doppler require CT evaluation

12 CT Renal Cysts B2 Minimally complex cysts - Few hairline septa which may enhance (not measurably) - Fine calcification in wall or septum - Homogenously hyperdense cyst < 3 cm (40-90 HU)

13 CT Renal cysts B2F BOSNIAK 2F cannot be considered benign without a period of observation (2-5 years) Introduced 2003* Thickened irregular or multiple septa No measurable enhancement Dense calcification *Israel & Bosniak, Radiology 2005; 236: 44-50

14 CT Renal cysts B4

15 CT Technique UNENHANCED 30 SECONDS 10 MINUTES 120 SECONDS

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17 Solid masses Size Enhancement Fat content Shape Surrounds History

18 Measurement of Hounsfield Units >20 Enhancement, equivocal 6 HU 30 HU 12 HU 63 HU

19 Change = 6HU = no follow up 38 HU 44 HU

20 Solid masses Size Enhancement Fat content Shape Surrounds History

21 CT - Angiomyolipoma? Macroscopic fat (- 20) Angiomyolipoma? Micro fat: -Pixel mapping line/square 4 pixels of fat attenuation (-10 HU) Measure on the un-enhanced phase 4.5% AML minimal fat Halpenny et al. Clin Rad 2010; 65:

22 Solid masses Size Enhancement Fat content Shape Surrounds History

23 Shape Tumour perinephric Infarct Treatment effect

24 Post partial nephrectomy

25 Solid masses Size Enhancement Fat content Shape Surrounds History

26 Post CT Cryotherapy

27 Indeterminate masses on CT Too small to characterise (< 5mm) Most renal lesions under 1cm will be benign cysts Psuedo-enhancement (> 10 HU) due to recon algorithm used to compensate for beam hardening. Seen in smaller and intra renal lesions. Especially on CT Urograms No precontrast scan

28 Does it go black on liver settings? WL 40 WW 400 WL 100 WW 150

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30 CT KUB Mass > 70 HU = 99% hyperdense cyst* Mass < 20 HU = simple cyst Recall for post contrast - Calcification - Attenuation HU *Jonisch et al Radiology 2007: 243:

31 MRI Characterisation of solid renal masses In and out of phase techniques, loss of signal in fat containing masses on OP T2W Coronal Fat saturated pre and post contrast T1W imaging (ax & cor) Enhancement = increase in SI on ROI of > 15%* *Hecht et al, Radiology 2004; 232:

32 Kwon et al, Int Urol & Nephrol 2015; 47: indeterminate renal masses on CT had MRI Surgical correlation 47 benign (AML, Onco, cysts) CT Sens 27.7% Spec 94.5% MRI Sens 68.1 Spec 91.8% 15 patients could have avoided surgery MRI has incremental benefit to distinguish RCC from indeterminate renal masses on CT

33 MRI Characterisation of cystic masses Better depiction of septa on T2 weighted imaging Use of subtraction same parameters both aquisitions (post subtracted from pre-contrast) Improved contrast resolution Calcification not seen No pseudo-enhancement.

34 Bosniak III

35 Role of Biopsy Lesions indeterminate by imaging alone Prior to treatment Reliable diff between RCC and Oncocytoma Reliable histological subtype and Fuhrman grade

36 Technique < 3cm CT guided Platelets < 50, INR <1.5 Prone / decubitus Breath held insp or exp 17 Gauge Coaxial needle 18 Gauge biospy needle 2 cores

37 Hu et al, Human Pathology, 2015; 46: consecutive core biospies (0.5-24cm, 78% small ) 89% positive (of these 77% malignant, 23% benign) 93% accurate in histological subtype of RCC 11% non diagnostic

38 Complications metanalysis of 16,000* Haemorrhage / haematuria Infection Adjacent organ puncture Renal loss 0.1% Mortality 0.031% Track seeding - < 0.01 for RCC. Non diagnostic / false negative 10% *Upport AJR 2010; 194:

39 Questions What would be the consequence of NOT characterising incidental lesions? Acceptance of diagnostic uncertainty Avoidance of overdiagnosis and unnecessary surveillance What would be the consequence of NOT following up incidental lesions?

40 What % of incidental masses are significant? 3001 CT colonograms 433 (14.4%) had a mass >1cm (mean 2.5) 5 were complex/solid 4 RCC s detected with mean FU 3.3 yrs % chance of malignancy Heterogeneity on post contrast CT is a feature of RCC O Connor SD, Pickhardt PJ, Kim DH, Oliva MR, Silverman SG. Incidental finding of renal masses at unenhanced CT: preva- lence and analysis of features for guiding management. AJR Am J Roentgenol 2011; 197(1):

41 B2F how long to FU? 198 patients with B2F 86.5% Incidental findings Followed up 2 years 98% unchanged class, 66% unchanged size. 2% had partial nephrectomy, 0.5% malignant. Imaging for 2 years Savings if discharged at 2 (per year) Raslan et al, J Clinical Urology 2016; 9;

42 B2F how long to FU? In a fiscally constrained system such as the NHS, clinicians have a duty to use the allocated resources responsibly, accepting there is a small risk of an adverse outcome Kings Fund: Better value in the NHS: The role of changes in clinical practice.

43 Surveillance of small solid renal masses YES YES? NO NO

44 Summary -Ignore Lesions < 1cm (unless heterogenous) on CT or MRI Homogenous lesions < 20 or > 70 HU - unenhanced CT Lesions that look black on liver windows PV CT Macroscopic fat < 2cm Single thin septated cyst on US > 60 yrs.

45 Summary Solid masses Size Enhancement Fat content Shape Cystic masses Bosniak Classification 2F No enhancement 3 Measureable enhancement in septa. Surrounds History

46 S Silverman, G Israel, Q Trinh Radiology 2015; 275: 28-42

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