All MRI examinations were performed using a clinical 3.0 T system (Ingenia, Phillips Healthcare, Best, Netherlands) with a 32-channel large anterior surface body coil combined with a posterior moveable coil. The respiration triggering device was placed under the anterior coil at the diaphragm level. All patients underwent a survey in two plans with the respiration trigger and two plans with breath-hold, respiration triggered T2-weighted (T2w) turbo spin-echo sequence in transversal and coronal plan, a fat-suppressed diffusion-weighted imaging (DWI) sequence in the transverse plane, and T1-weighted (T1w) DIXON sequence performed both before and 25 s after administration of a gadolinium-containing agent for corticomedullary phase as well as at 120 s after administration for the nephrographic phase. The MRI protocol is presented in [Table 1 ]. The contrast agent was injected rapidly through an antecubital vein and immediately followed by a flush of 30 mL saline solution (0.9% NaCl). Gadovist (Bayer, Leverkusen, Germany) was used as a contrast agent and administered at 0.1 mL/kg, and a maximum of 7.5 mL was injected. For all MRI sequences, sensitivity encoding was used. [Figure 2 ] presents the sequences used in the assessments according to Cornelis’ proposed algorithm.
Before receiving histopathology results and diagnosis, two radiologists (OG and JTA), with 9 and 14 years MRI experience in the interpretation of renal tumors, assessed and described in consensus the images in the prescribed order. For each tumor, the radiologists evaluated tumor appearance, one sequence at a time, according to Cornelis et al.’s algorithm [Table 2 ].[18 (link)] If an MRI diagnosis was established after 1–4 sequences, all remaining sequences were still evaluated. For example, high signal intensity in the first sequence (T2w) suggests cc-RCC or OC, [Table 2 ]. If the tumor shows a signal drop on the out-phase on the second sequence (dual chemical shift MRI), cc-RCC or AML is suggested. The combination of the first two sequences excludes all remaining tumor types, and cc-RCC is proposed as the diagnosis. In another scenario, a tumor might present intermediate/middle intensity during the first sequence, suggesting Ch-RCC. In these instances, images from all remaining sequences were still evaluated.
Tumor size was measured in two dimensions on the transverse T2w image: medial-lateral and anterior-posterior, where the largest diameter was noted.
Before receiving histopathology results and diagnosis, two radiologists (OG and JTA), with 9 and 14 years MRI experience in the interpretation of renal tumors, assessed and described in consensus the images in the prescribed order. For each tumor, the radiologists evaluated tumor appearance, one sequence at a time, according to Cornelis et al.’s algorithm [
Tumor size was measured in two dimensions on the transverse T2w image: medial-lateral and anterior-posterior, where the largest diameter was noted.
