diagnostics

Interesting Image An Incidental Renal : 18F-Choline PET/MRI

Andrew Mallia 1,2,*, Usman Bashir 1, James Stirling 1,2, Konrad Wolfe 3, Vicky Goh 1,4 and Gary Cook 1,2

1 Imaging Department, Division of Imaging Sciences and Biomedical Engineering, Kings College London, London SEI 7EH, UK; [email protected] (U.B.); [email protected] (J.S.); [email protected] (V.G.); [email protected] (G.C.) 2 Clinical PET Centre, St Thomas’ Hospital, London SEI 7EH, UK 3 Department of Pathology, Southend University Hospital NHS Foundation Trust, SS0 0RY, UK; [email protected] 4 Department of Radiology, Guy’s & St Thomas’ Hospitals NHS Foundation Trust, London SEI 7EH, UK * Correspondence: [email protected]; Tel.: +44-207-188-4988

Academic Editor: Andreas Kjaer Received: 19 February 2016; Accepted: 30 March 2016; Published: 6 April 2016

Abstract: PET/MRI is a new hybrid imaging modality and has the potential to become a powerful imaging tool. It is currently one of the most active areas of research in diagnostic imaging. The characterisation of an incidental renal lesion can be difficult. In particular, the differentiation of an oncocytoma from other solid renal lesions such as renal cell (RCC) represents a diagnostic challenge. We describe the detection of an incidental renal oncocytoma in a 79-year gentleman who underwent a re-staging 18F-Choline PET/MRI following a rise in PSA values (4.07, nadir 1.3).

Keywords: PET/MRI; 18F-Choline; oncocytoma

Diagnostics 2016, 6, 14; doi:10.3390/diagnostics6020014 www.mdpi.com/journal/diagnostics Diagnostics 2016, 6, 14 2 of 3 Diagnostics 2016, 6, 14

FigureFigure 1. PET/MRIPET/MRI isis a a new new hybrid hybrid imaging imaging modality, modality, which which has recentlyhas recently been introducedbeen introduced into clinical into clinicalpractice practice [1]. We [1]. present We apresent 79 year-old a 79 year gentleman‐old gentleman with a past with history a past of history prostate of cancer prostate Gleason cancer 6 Gleason(3 + 3) treated 6 (3 + with3) treated brachytherapy with brachytherapy who underwent who underwent a re-staging a 18reF-Choline‐staging 18F PET/MRI‐Choline PET/MRI scan following scan followinga rise in PSA a rise (4.07, in PSA nadir (4.07, 1.3). nadir Apart 1.3). from Apart an abnormalfrom an abnormal focus at focus the base at the of thebase left of seminalthe left seminal vesicle, vesicle,which was which suspicious was suspicious for disease for recurrence,disease recurrence, the 18F-Choline the 18F‐Choline PET/MRI PET/MRI showed showed intense intense tracer uptake tracer uptakewithin within a solid a 34 solid mm 34 right mm lowerright lower pole renalpole renal mass mass (a–c, (reda–c, arrows),red arrows with), with MRI MRI features features typical typical for foran oncocytoma:an oncocytoma: iso/hypo iso/hypo intense intense signal signal on T1-weightedon T1‐weighted (d); ( hyperintensed), hyperintense on T2-weightedon T2‐weighted (e); and(e), andcentral central area area of low of signallow signal intensity intensity on both on T1-weightedboth T1‐weighted and T2-weighted and T2‐weighted images images suggestive suggestive of a central of a centralscar (d ,escar); The (d, lesione). The appeared lesion appeared hindered hindered on high bonvalue high (b b-value value = ( 900b‐value s/mm = 9002) diffusion s/mm2) weighteddiffusion weightedsequences sequences (f). A right ( laparoscopicf). A right laparoscopic radical radical wasnephrectomy performed was subsequently. performed Macroscopically, subsequently. Macroscopically,a lower pole tan-coloured a lower pole tumour tan‐ wascoloured present. tumour Sections was of present. the tumour Sections showed of the an tumour encapsulated showed lesion an encapsulatedcomprised of lesion packets comprised of oncocytic of packets cells staining of oncocytic positively cells for staining CK7, in positively keeping with for CK7, an in keeping with(g (200 anˆ oncocytomasmagnification) (g and (200×h (400magnification)ˆ magnification)). and h (400× The differentiation magnification)). of an The oncocytoma differentiation from of other an oncocytomasolid renal lesions, from other in particular solid renal renal lesions, cell carcinomain particular (RCC), renal iscell a carcinoma diagnostic (RCC), challenge is a [ 2diagnostic]. MRI is challengefrequently [2]. used MRI for is the frequently detection used and differentiationfor the detection of renal and differentiation masses, including of renal oncocytomas. masses, including However oncocytomas.the specificity ofHowever MRI is reducedthe specificity since the of features MRI is ofreduced oncocytomas since the show features considerable of oncocytomas similarities show with considerablethose of RCCs similarities [3]. Diffusion-weighted with those of RCCs imaging [3]. (DWI)Diffusion can‐weighted augment MRIimaging characterisation (DWI) can augment of renal MRIlesions, characterisation but there is an of overlap renal inlesions, the ADC but values there ofis RCCsan overlap and oncocytomas. in the ADC Different values of authors RCCs haveand oncocytomas.shown that malignant Different renalauthors tumours have shown have lower that malignant ADC values renal when tumours compared have tolower benign ADC tumours values whensuch ascompared oncocytomas to benign [4]. However, tumours other such studies as oncocytomas have demonstrated [4]. However, similar ADC other values studies for thesehave demonstratedtwo tumour types similar [5]. PET/MRIADC values maximises for these the diagnostictwo tumour information types [5]. available. PET/MRI This maximises particular casethe diagnosticdemonstrated information its value available. in the characterisation This particular of case an incidental demonstrated renal its lesion, value thus in the avoiding characterisation the need offor an further incidental diagnostic renal testslesion, and thus potentially avoiding reducing the need unnecessary for further surgicaldiagnostic resections. tests and Choline-avid potentially reducingoncocytomas unnecessary have not surgical been described resections. before, Choline but‐ cannotavid oncocytomas be differentiated have not from been renal described cell before, buton the cannot PET be characteristics differentiated alone. from The renal addition cell carcinomas of MRI features on the led PET to characteristics a confident PET/MRI alone. The diagnosis addition of ofan MRI oncocytoma. features led All proceduresto a confident performed PET/MRI in diagnosis this study of were an oncocytoma. in accordance All with procedures the ethical performed standards inof thethis institutional study were and/or in accordance national with research the committee.ethical standards of the institutional and/or national research committee.

Conflicts of Interest: The authors declare no conflict of interest.

2 Diagnostics 2016, 6, 14 3 of 3

Conflicts of Interest: The authors declare no conflict of interest.

References

1. Jadvar, H.; Colletti, P. Competitive advantage of PET/MRI. Eur. J. Radiol. 2014, 83, 84–97. [CrossRef] [PubMed] 2. Ng, K.L.; Rajandram, R.; Morais, C.; Yap, Y.; Samaratunga, H.; Gobe, C.G.; Wood, S.T. Differentiation of oncocytoma from chromophobe (RCC): Can novel molecular biomarkers help solve an old problem? J. Clin. Pathol. 2014, 67, 97–104. [CrossRef][PubMed] 3. Nikken, J.J.; Krestin, G.P. MRI of the , state of the art. Eur. Radiol. 2007, 17, 2780–2793. [CrossRef] [PubMed] 4. Prettner-Pallwein, L.; Flory, D.; Rotter, C.R.; Pogner, K.; Syré, G.; Fellner, C.; Frauscher, F.; Aigner, F.; Krause, F.S.; Fellner, F. Assessment and characterisation of common renal masses with CT and MRI. Insights Imaging 2011, 2, 543–556. [CrossRef][PubMed] 5. Hotker, A.; Mazaheri, Y.; Wibmer, A.; Zheng, J.; Moskowitz, C.S.; Tickoo, S.K.; Russo, P.; Hricak, H.; Akin, O. Use of DWI in the differentiation of renal cortical tumors. AJR 2016, 206, 100–105. [CrossRef][PubMed]

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