The enhancement parameters in CT in evaluation of type and grade of renal tumors
Article published in Urologia Polska 2008/61/Supl. 1.

authors

Marek Urban, Luiza Grzycka-Kowalczyk, Grzegorz Staśkiewicz, Krzysztof Bar, Andrzej Drop

Katedra i Klinika Urologii AM w Lublinie
I Zakład Radiologii Lekarskiej AM w Lublinie

summary

Introduction.

Renal cell carcinoma (RCC) accounts for about 3% of all adult human neoplasms. It is the most lethal cancer of the genitourinary tumors. A few histological subtypes of RCC may be distinguished. Although they play some role in prognosis, tumor grade (G) remains the most important prognostic factor.

Objectives.

The aim of the study was to evaluate MSCT imaging of renal tumors, estimate a pattern of tumor enhancement with the reference to abdominal aorta and to measure the differences in attenuation values according to grade of differentiation (G) among clear cell subtype.

Materials and methods.

The analysis encompassed CT examinations of 58 patients with renal tumors subjected to operative procedures directly after CT performed according to accepted protocol. All patients underwent multiphase CT examination (8-row and 64-row scanner GE Light Speed Ultra), with precontrast scanning as well as contrast – enhanced acquisition obtained during arterial (AP), corticomedullary phase (CMP) and excretory phase (EP). Histological examination revealed 48 cases of clear cell renal carcinoma (including 5 cystic types), 6 papillary renal cell tumors and 4 oncocytomas. The attenuation in three regions of interest (ROI) was measured on precontrast

scanning and after IV administration of contrast agent in all phases.

Results.

Pairwise comparison showed significantly different attenuation values during AP between clear cell and papillary subtypes – with higher enhancement values in peripheral part of clear cell tumor. In all RCC subtypes, the peripheral parts of tumor enhanced significantly less in AP (p=0,043) then relevant part of oncocytomas; with median attenuation respectively 83HU, 130HU. The analysis of attenuation values among clear cell subtypes showed significant difference on native phase in peripheral parts

of G-2 and G-3 tumors [(p=0,048) with median attenuation respectively 37,5 HU, 44,5HU] as well as enhancement parameters on CMP in central parts of G-2 and G-3 tumors [(p=0,016) with median attenuation respectively 40HU and 31HU. Tumor density in reference to aorta showed higher enhancement value (on CMP) among oncocytomas then subtypes of RCC.

Conclusions.

The degree of enhancement during post-contrast scanning can be a valuable parameter for differentiating among renal tumors and evaluating the grade (G) of clear cell subtype of RCC.