Is Preoperative Magnetic Resonance Imaging in a Daily Clinical Setting Useful to Evaluate Tumor Invasion Beyond the Pseudocapsule in Renal Cell Carcinoma?

Background: We wanted to clarify whether preoperative magnetic resonance imaging (MRI) in the clinical setting can evaluate the pathologic pseudocapsule (PC) morphology with high accuracy in renal cell carcinoma (RCC). Methods: We retrospectively analyzed 34 consecutive patients who underwent MRI (1.5 or 3.0T, 5 mm slices) prior to partial nephrectomy (PN) for RCC at our institution between January 2010 and December 2019. First, the correlation between PC morphology (complete or incomplete) and tumor infiltration to the renal parenchyma was examined as pathologic validation. Second, the concordance rate of PC morphology between pathologic tissue and preoperative MRI was evaluated as radiologic validation. Third, risk factor for renal parenchymal invasion in RCC was analyzed. Results: In the pathologic validation, parenchymal invasion rates were 11% and 28% in the “complete PC” and “incomplete PC” groups, respectively. In the radiologic validation, pathological PC morphology could be diagnosed on preoperative MRI in 17 patients (50.0%). “None PC” on MRI had the lowest positive predictive value (PPV) (0%), “partial PC” on MRI had a good PPV (76.5%), “complete PC” on MRI had a relatively low PPV (33.3%). Unfortunately, these data were insufficient for diagnostic accuracy. As risk factor for renal parenchymal invasion in RCC, only pathologic subtype (non-clear cell) was found to have significant differences in the multivariate analysis. Conclusion: The results of this study suggest that renal tumors with pathologically incomplete PC have a high possibility of renal parenchymal invasion. However, it is currently difficult to accurately evaluate pathologic PC morphology by preoperative MRI in the clinical setting

Usefulness of Preoperative 18F-FDG PET/CT for Patients with Thymic Epithelial Tumors

[Background] The purpose of this study was to investigate the relationship between preoperative FDG-PET parameters and the World Health Organization (WHO) classification or Masaoka staging system of thymic epithelial tumors. [Methods] We retrospectively reviewed 32 patients with histologically proven thymic epithelial tumors who underwent FDG-PET/CT before surgical resection. FDG-PET parameters, including the maximum standardized uptake value (SUVmax), metabolic tumor volume (MTV), and total lesion glycolytic activity (TLG), were measured. These PET parameters were compared in the Masaoka staging system and WHO classification. A receiver operating characteristics (ROC) analysis was performed to identify the cut-off values of PET parameters for the accurate differentiation of early and advanced stages in the Masaoka staging system. [Results] There were 17 low-risk thymomas (1 type A, 9 type AB, and 7 type B1), 8 high-risk thymomas (4 type B2 and 4 type B3), and 7 thymic carcinomas (7 squamous cell carcinoma). Their Masaoka stages were as follows: 24 in the early stage (stages I and II) and 8 in the advanced stage (stage III). Regarding the WHO classification, only SUVmax showed a significant difference (P < 0.05). In the Masaoka stage, all PET parameters were significantly higher in the advanced stage than in the early stage (P < 0.05). In the ROC analysis to predict the early and advanced stages in thymic epithelial tumors, the area under the curve was the highest for TLG among the PET parameters examined and the cut-off value of TLG for discriminating the early from advanced stage with maximal sensitivity and specificity was 30.735. [Conclusion] Although volumetric PET parameters, such as MTV and TLG, did not correlate with the WHO classification, a significant correlation was observed between SUVmax and the WHO classification. In the Masaoka staging system, volumetric PET parameters may achieve more precise staging than SUVmax

Technetium-99m Methoxyisobutyl Isonitrile Scintigraphy of Bone Metastasis in Three Patients with Differentiated Thyroid Cancer

We studied the usefulness of ^Tc-methoxyisobutyl isonitrile (MIBI) scintigraphy in the detection of bone metastases and in evaluation of therapeutical response to ^I-Na in three patients with differentiated thyroid cancer. On ^Tc-MIBI scintigraphy, increased accumulations were observed in all bone metastatic lesions (14 lesions), whereas on bone scintigraphy using ^Tc-hydroxymethylene diphosphonate (^Tc-HMDP) both increased (eight lesions, 57%) and decreased (six lesions, 43%) accumulations were observed. Within two months after ^I-Na treatment, all 14 lesions were unchanged on bone scintigraphy. However, on ^Tc-MIJBI scintigraphy, disappearance of uptake (six lesions, 43%) and decreased uptake (seven lesions, 50%) were observed in 13/14 lesions (93%). Therefore, ^Tc-MIBI scintigraphy was useful not only in the detection of bone metastatic lesions but also in evaluation of the therapeutical response to ^I-Na in differentiated thyroid cancer