Image Quality and Lesion Detection of Multiplanar Reconstruction Images Using Deep Learning: Comparison with Hybrid Iterative Reconstruction.

Background: We assessed and compared the image quality of normal and pathologic structures as well as the image noise in chest computed tomography images using "adaptive statistical iterative reconstruction-V" (ASiR-V) or deep learning reconstruction "TrueFidelity". Methods: Forty consecutive patients with suspected lung disease were evaluated. The 1.25-mm axial images and 2.0-mm coronal multiplanar images were reconstructed under the following three conditions: (i) ASiR-V, lung kernel with 60% of ASiR-V; (ii) TF-M, standard kernel, image filter (Lung) with TrueFidelity at medium strength; and (iii) TF-H, standard kernel, image filter (Lung) with TrueFidelity at high strength. Two radiologists (readers) independently evaluated the image quality of anatomic structures using a scale ranging from 1 (best) to 5 (worst). In addition, readers ranked their image preference. Objective image noise was measured using a circular region of interest in the lung parenchyma. Subjective image quality scores, total scores for normal and abnormal structures, and lesion detection were compared using Wilcoxon's signed-rank test. Objective image quality was compared using Student's paired t-test and Wilcoxon's signed-rank test. The Bonferroni correction was applied to the P value, and significance was assumed only for values of P < 0.016. Results: Both readers rated TF-M and TF-H images significantly better than ASiR-V images in terms of visualization of the centrilobular region in axial images. The preference score of TF-M and TF-H images for reader 1 were better than that of ASiR-V images, and the preference score of TF-H images for reader 2 were significantly better than that of ASiR-V and TF-M images. TF-M images showed significantly lower objective image noise than ASiR-V or TF-H images. Conclusion: TrueFidelity showed better image quality, especially in the centrilobular region, than ASiR-V in subjective and objective evaluations. In addition, the image texture preference for TrueFidelity was better than that for ASiR-V.

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.

CT and MR imaging findings of bilateral ovarian metastasis from renal cell carcinoma: a case report.

Secondary ovarian involvement by renal cell carcinoma rarely occurs. Here, we describe the computed tomography and magnetic resonance imaging findings of bilateral ovarian metastases from renal cell carcinoma that demonstrated heterogeneous strong contrast enhancing tumors with flow voids around and within the tumors. In addition, the apparent diffusion coefficients of the malignant tumors were high. These findings were similar to those of renal cell carcinomas at primary and other metastatic sites.

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.

Correlation of apparent diffusion coefficients measured by diffusion-weighted MR imaging and standardized uptake values from FDG PET/CT in metastatic neck lymph nodes of head and neck squamous cell carcinomas.

Both diffusion-weighted magnetic resonance imaging and fluorodeoxyglucose positron emission tomography/computed tomography are oncological imaging techniques. The aim of this study was to assess any correlation between apparent diffusion coefficients and standardized uptake value in metastatic neck lymph nodes of head and neck squamous cell carcinomas.

Relationship between (123)I-MIBG scintigrams and REM sleep behavior disorder in Parkinson's disease.

BACKGROUND: Uptake of (123)I-labeled meta-iodobenzylguanidine (MIBG) in myocardial scintigrams has been shown to be as low in patients with idiopathic RBD as in Parkinson's disease (PD) patients. AIM FOR STUDY: To clarify whether the existence of RBD accelerates autonomic dysfunction in PD, we investigated the association between MIBG scintigraphic findings and RBD measures among non-dementia PD patients. SUBJECTS & METHODS: We conducted clinical interviews to assess REM sleep behavior disorder (RBD) symptoms, and performed polysomnograms (PSG) recordings and MIBG scintigrams on 49 PD patients. The patients were divided into three groups (PD with clinical RBD, PD with subclinical RBD, and PD with normal REM sleep). RESULTS: PD patients with clinical RBD had reduced MIBG uptake as determined by heart-to-mediastinum ratios of the delayed image compared to those with subclinical RBD and those with normal REM sleep. Multiple linear regression analysis revealed that only the existence of RBD symptoms was significantly associated with reduced MIBG uptake among PD patients without dementia after adjusting for demographic and PD symptom-related variables. CONCLUSION: PD patients with clinical RBD might suffer from a wider α-synuclein pathology, including reduced cardiac sympathetic ganglia function as reflected by a lowered MIBG uptake.

Intrathoracic splenosis: evaluation by superparamagnetic iron oxide-enhanced magnetic resonance imaging and radionuclide scintigraphy.

Splenosis represents the heterotopic autotransplantation of splenic tissue after either splenic trauma or surgery. Intrathoracic splenosis is a rare condition resulting from concomitant rupture of the spleen and the left hemidiaphragm. We report a case of splenosis in a 41-year-old male patient who had experienced severe thoracoabdominal injury including rupture of the spleen and left hemidiaphragm and post-traumatic splenectomy 20 years previously. Abnormal opacities in the cardiac region were noted on a chest radiograph at an annual checkup. Computed tomography (CT) of the chest demonstrated multiple, well-circumscribed pleura-based nodules at the posterior base of the left hemithorax and the left subdiaphragmatic area. On magnetic resonance imaging (MRI), the lesions were hypointense on T1-weighted images and hyperintense on T2-weighted images. After administration of superparamagnetic iron oxide (SPIO), the lesions showed decreased signal intensity but remained slightly hyperintense relative to liver parenchyma on T2-weighted images. (99m)Tc-labeled Sn colloid scintigraphy revealed multiple areas of increased activity consistent with the lesions on the CT and MRI scans. In addition to the history of splenic trauma and left hemothorax, SPIO-enhanced MRI and radionuclide scintigraphy, which can demonstrate phagocytic ability in the ectopic splenic tissue, were useful for confirming the diagnosis.

Analysis of three-dimensional microarchitecture and degree of mineralization in bone metastases from prostate cancer using synchrotron microcomputed tomography.

Bone architecture and mineralization are generally considered to be important components of bone quality, and determine bone strength in conjunction with bone mineral density. Although the features of bone quality have recently been studied under conditions in which bone density decreases, such as osteoporosis, little is known in osteosclerotic diseases. In this study, we compared the trabecular bone microarchitecture and degree of mineralization between osteoblastic bone metastasis and degenerative osteosclerosis using synchrotron radiation microcomputed tomography (SR-microCT). Small cubes of lumbar vertebrae were excised postmortem from the sites of osteoblastic metastasis, degenerative osteosclerosis, and comparative sites of normal subjects without skeletal lesions. The samples were imaged at high spatial resolution (voxel size = 6 microm) using the SR-microCT system developed at the synchrotron facility (SPring-8), Hyogo, Japan. The three-dimensional (3D) image data were then analyzed for the morphological parameters and the degree of mineralization of bone (DMB). Trabecular bone in metastatic lesions showed a highly connected and isotropic network pattern compared with the normal samples. Although the trabecular surface was markedly irregular in osteoblastic metastases, no significant difference was found in the mean trabecular thickness (Tb.Th) between osteoblastic metastases and normal tissue. The DMB of trabeculae in metastatic lesions had a broader range and lower mean than that of the normal tissue. In contrast, trabecular bone in degenerative osteosclerotic lesions showed a similar degree of anisotropy (DA) and connectivity to the normal tissue, whereas the trabecular thickness was greater in the degenerative osteosclerotic lesions. No significant difference in DBM between degenerative osteosclerosis and normal tissue was detected. These results characterize the difference in bone quality between osteoblastic bone metastasis and degenerative osteosclerosis. Further study on the relationship between bone quality and bone strength in these osteosclerotic lesions would improve our understanding of the pathogenesis of bone fragility.