Role of multiphasic multi-detector computed tomography (MDCT) in the diagnosis and staging of solid neoplastic renal masses

Abstract

Objectives: The aim of this study was to assess the role of multi-detector computed tomography (MDCT) in diagnosis and preoperative staging of solid renal masses. Patients and methods: During two years duration we prospectively evaluated 56 patients with solid renal lesions previously detected by US. All patients underwent multiphasic CT scanning for the kidneys and urinary tract following a preset scanning protocol that included unenhanced, corticomedullary phase (CMP), nephrograhic phase (NP) and excretory phase (EP) scanning. The images obtained in the excretory delayed phase were reconstructed in different planes to obtain 2D and 3D reformatted images providing volume rendering VR and maximum intensity projection (MIP) CTU images. Curved reformatting was sometimes used for the ureter. The numbers of lesions detected in all three phases were determined. Results of CT scan were compared with histopathology or constellation of clinical and imaging patient data. Results: A total of 61 masses were detected in 56 cases, 51 cases had unilateral masses (91%), 5 cases had bilateral masses (9%). The different pathologies encountered in the study were RCC 39 masses (64%), Wilm’s tumor 3 masses (4.9%), transitional cell carcinoma 3 masses (4.9%), angiomyolipoma 7 masses (11.5%), lymphoma 6 masses (9.8%), metastasis one mass (1.6%), angiomyolipoma associated with RCC two masses (3.3%). Lymph nodal metastasis, renal vein, IVC thrombosis and distant metastatic spread in different pathologies were assessed. The attenuation HU values calculated in the early CMP for all cases of RCC had a mean value of 80.5 HU (STD 45.7) while the mean values in NP and EP were 70.6 HU (STD 25.4) and 51.3 HU (STD 19.2) respectively. A pattern of enhancement was detected in all cases of RCC in the form of rapid wash out of contrast and decrease of attenuation (HU) by time throughout different phases. Significant difference between HU in CMP and EP in cases of RCC (P value = 0.0002) and difference between HU in NP and EP in cases of RCC (P value < 0.00001) were found. Conclusion: Multiphase multislice computed tomography combined with CT angiography and CT urography have a major role in solid renal neoplastic masses’ diagnosis, characterization and differentiating benign and malignant tumors.