Can dynamic multidetector computerized tomography detect renal cell carcinoma subtypes?

Original Article Turk J Med Sci 2010; 40 (1): 31-38 © TÜBİTAK E-mail: doi:10.3906/sag-0904-53 Can dynamic multidetector computerized tomography detect renal cell carcinoma subtypes? Ayhan DİRİM1, Nihal TUTAR2, Levent PEŞKİRCİOĞLU1, Hüseyin ÇELİK1, Mehmet İlteriş TEKİN1, Hakan ÖZKARDEŞ1 Aim: To evaluate the efficacy of the biphasic and triphasic dynamic multidedector computerized tomography (MDCT) in the preoperative prediction of histological subtypes of renal cell carcinoma (RCC). Materials and methods: The preoperative dynamic MDCT findings of 51 patients with renal mass who had undergone nephrectomy were reviewed retrospectively. Twenty-five of the patients had biphasic (portal and excretory) and 26 had triphasic (arterial, portal, and excretory) MDCT images. Tumor size, presence of calcification, tumor-aorta attenuation values in all phases and homogeneicity of the tumor were noted for every patient. In heterogeneous tumors, the minimum and maximum attenuation values were noted to determine the extent of heterogeneicity. These data were compared for histopathological subtypes of the tumors. Results: In 8 patients, calcifications were detected in the mass although there were no significant differences among tumor subtypes with regard to the presence of calcification. In 33 patients the tumor was hypervascular with 24 clear type and clear type RCC showed more prominent contrast enhancement than papillary RCC. The enhancement degree showed no significant difference among other tumor subtypes. Moreover, when biphasic and triphasic computed tomography (CT) findings were compared, the positive predictive value of triphasic CT in detecting hypervascular clear tumors was greater (17/18; 94.4% versus 7/11; 63.6%). Conclusion: The dynamic MDCT technique appears to be useful in preoperative evaluation of renal masses suspected of being malignant and may also provide information about the histopathological subtype of RCC. Key words: Multidedector computerized tomography, renal cell carcinoma, renal cancer subtypes Dinamik multidedektör komputerize tomografi renal hücreli kanser subtiplerini belirleyebilir mi? Amaç: Renal hücreli kanser (RHK) histolojik subtiplerinin preoperatif tahmininde bifazik ve trifazik dinamik multidedektör komputerize (bilgisayarlı) tomografinin (DMKT) etkinliğini değerlendirmek. Yöntem ve gereç: Renal kitle nedeniyle nefrektomi yapılan 51 hastanın preoperatif dinamik MDKT bulguları retrospektif olarak değerlendirildi. Yirmibeş olguda bifazik (portal ve ekskretuar), 26 olguda ise trifazik (arteryal, portal, ve ekskretuar) MDKT görüntüleri elde edildi. Her olgunun tümör çapı, kalsifikasyon varlığı, her fazdaki tümör-aorta atenüasyon değerleri ve tümör homojenitesi belirlendi. Heterojen tümörlerde heterojenite farkı/derecesini belirlemek için minimum ve maksimum atenüasyon değerleri not edildi. Bu veriler tümörün histopatolojik subtipleriyle karşılaştırıldı. Bulgular: Sekiz olguda kitlede kalsifikasyon saptandı ancak kalsifikasyon varlığı ile tümör subtipleri arasında bir farklılık sözkonusu değildi. Otuzüç olguda tümör hipervaskülerdi. Bu olguların 24’ü şeffaf hücreli tipteydi ve şeffaf hücreli tip papiller tipe göre daha belirgin kontrastlanma göstermekteydi. Diğer tümör tipleri arasında kontrastlanma derecesi açısından farklılık izlenmedi. Yine bifazik ve trifazik tomografi bulguları karşılaştırıldığında trifazik tomografinin hipervasküler şeffaf hücreli tümörü saptamadaki pozitif prediktif değeri bifazikten yüksekti (17/18; % 94,4’e karşın 7/11; % 63,6). Sonuç: Dinamik MDKT tekniği malignite şüphesi olan renal kitlelerin preoperatif değerlendirmesinde yararlı olması yanında RHK’in histopatolojik subtiplerinin belirlenebilmesi konusunda da bilgi verebilir. Anahtar sözcükler: Multidedektör komputerize tomografi, renal hücreli karsinom, renal kanser subtipleri Received: 30.04.2009 – Accepted: 15.10.2009 1 Department of Urology, Faculty of Medicine, Başkent University, Ankara - TURKEY 2 Department of Radiology, Faculty of Medicine, Başkent University, Ankara - TURKEY Correspondence: Ayhan DİRİM, Department of Urology, Faculty of Medicine, Başkent University, 5. Sokak, No: 48, 06490 Bahçelievler, Ankara - TURKEY E-mail: 31 Can CT detect RCC subtypes Introduction Computed tomography (CT) remains to be the gold standard modality for diagnosing and staging renal neoplasms, and the wide use of CT for abdominal imaging has led to earlier detection of many small renal neoplasms (1-3). Preoperative estimation of the tumor subtype may help to choose the appropriate treatment modality and provide information for predicting postoperative prognosis. Papillary RCC are associated with a better prognosis than other cell types at a similar stage, but papillary renal cancers are more frequently multiple, bilateral, and can be hereditary (4, 5). These characteristics of papillary RCC may let the physician to plan a partial nephrectomy in selected patients if it can be detected preoperatively by MDCT. Materials and methods Patients The dynamic MDCT findings of 51 patients who had undergone radical (n = 41) or partial (n = 10) nephrectomy between May 2005 and October 2007 because of renal mass were reviewed retrospectively. Twenty-five of the patients had biphasic (portal and excretory) and 26 had triphasic (arterial, portal, and excretory) MDCT images. Tumor size, presence of calcification and necrosis, and tumor–aorta attenuation values in all phases and homogeneicity of the tumor were recorded for every patient. In heterogeneous tumors the minimum and maximum attenuation values were recorded to determine the extent of heterogeneicity. These data were compared for histopathological subtypes of tumors. CT examination Triphasic renal CT was performed on either a Somatom Plus 4 (Siemens Medical Systems, Germany) or a Volume Zoom (Siemens Medical Systems, Germany) 16 detector scanner. Oral contrast agent was administered to all patients. Each patient was scanned before intravenous contrast administration for precontrast imaging. Then arterial, portal, and excretory phase images were obtained. Delay time was 20 seconds for the arterial phase, 60 seconds for the portal phase, and 5 min for the excretory phase images. Slice thickness was 5 mm for all phases. Nonionic contrast media (150 mL) was injected using a mechanical injector at a rate of 4.5 mL/sec. Axial CT images were 32 reconstructed after the scanning had finished in axial and coronal planes using the multiplanar reconstruction (MPR) technique in each patient. Statistical analysis The Kruskal Wallis analysis of variance and chisquare tests were used as statistical methods. A P value of 0.05 was accepted as cut-off for statistical significance. The analyses were done using SPSS 11.0 for Windows. Results Patients There were 22 female and 29 male patients with a mean age of 59.8 years (range: 34-80). The male-tofemale ratio was 1.07/1 in clear cell RCC, 5.5/1 in papillary RCC, and 1/1 in chromophobe cell RCC. Wh (...truncated)