Yoshiaki Egashira

High b-value diffusion-weighted MRI in differentiation between benign and malignant polypoid gallbladder lesions.

Background Several studies have reported the effectiveness of high b-value diffusion-weighted MR imaging (DWI) in the abdominal region, and have found that various malignant tumors may show high signal intensity on DWI, reflecting their high cellularity and/or their long relaxation time. The value of ADC measurement has also been documented for the diagnosis of several abdominal malignancies. Purpose To retrospectively evaluate the usefulness of high b-value DWI in differentiating between benign and malignant polypoid gallbladder lesions. Material and Methods The study population consisted of 10 benign (three hyperplastic polyps and seven adenomas) and 13 malignant (all adenocarcinomas) polypoid gallbladder lesions. DWI was evaluated by two observers. Qualitatively, the signal intensity of the lesions on DWI was visually evaluated and categorized as iso, high, or very high. Quantitatively, the ADC values of the lesions were measured from ADC maps. Statistical analysis was performed using a two-tailed Fishers exact test and the Mann-Whitney test, respectively. Results Qualitative analysis revealed a statistical difference (P = 0.0041). Six of 10 benign lesions were categorized as iso, and the remaining four were categorized as high. In the 13 malignant lesions, one was categorized as iso, five as high, and seven as very high. The ADC values of the malignant lesions (1.34 ± 0.50 × 10–3 mm2/sec) were significantly lower than those of the benign lesions (2.26 ± 0.44 × 10–3 mm2/sec) (P = 0.00016). Conclusion High b-value DWI may be useful for differentiating between benign and malignant polypoid gallbladder lesions by the visual assessment of DWI and ADC measurement.

Noninvasive method for mapping CVR in moyamoya disease using ASL-MRI

PURPOSE To project a noninvasive method for mapping cerebrovascular reserve (CVR) in moyamoya disease (MMD) using ASL-MRI. METHODS 16 MMD patients underwent cerebral blood flow (CBF) examinations by standard ASL-MRI, pulse-wave-synchronized ASL-MRI (pulsy ASL-MRI) which tagged the arterial blood coincident with a peak of a pulse wave, and single photon emission computed tomography (SPECT) imagings with iodine-123-N-isopropyl-p-iodoamphetamine in the resting (rest-IMP) and after acetazolamide challenge (ACZ-IMP). Hemispheric 32-sided cerebral blood flow (CBF) values were measured with normalized CBF maps created from standard ASL-MRI (standard-ASL value), pulsy ASL-MRI (pulsy-ASL value), rest-IMP (rest-IMP value), and ACZ-IMP (ACZ-IMP value). CVR based on rest-IMP and ACZ-IMP values (IMP-CVR) was calculated. ASL-CVR was also calculated on the basis of corrected standard-ASL values and pulsy-ASL values, which were adjusted to the ACZ-IMP values and rest-IMP values, respectively, by the least-squares method. We assessed the relationships between rest-IMP values and pulsy-ASL values, ACZ-IMP values and standard-ASL values, and IMP-CVR and ASL-CVR. RESULTS Significant relationships were observed between rest-IMP values and pulsy-ASL values (correlation coefficient (r=0.557, p<0.01)), ACZ-IMP values and standard-ASL values (r=0.825, p<0.01), and IMP-CVR and ASL-CVR (r=0.736, p<0.01). CONCLUSIONS ASL-MRI is equivalent to SPECT and that it might serve as a noninvasive method for mapping CVR in MMD.

Operative strategy for descending and thoracoabdominal aneurysm repair with preoperative demonstration of the Adamkiewicz artery.

BACKGROUND Our study aimed to demonstrate the efficacy of preoperative intraarterial computed tomographic angiography to identify the Adamkiewicz artery (AKA). We also aimed to investigate the impact of identification of the AKA on the strategy for preventing spinal cord injury. METHODS Thirty-seven patients (24 cases of descending aortic aneurysms and 13 cases of thoracoabdominal aortic aneurysms), were studied. Average age was 63.8 years old. A pigtail catheter was inserted into the descending aorta and its tip was located immediately below the left subclavian artery. Subsequently, intraarterial computed tomographic angiography was performed and the segmental artery to the AKA was identified. Aneurysms were replaced electively with prosthetic graft in all cases. In cases where the aortic segment that supplied the AKA was cross-clamped, the identified segmental artery-AKA was selectively perfused. In these cases, the segmental artery-AKA was reconstructed with an interposition graft. RESULTS Intraarterial computed tomographic angiography successfully identified the segmental artery-AKA in all patients. The average number of AKA observed per patient was 1.3± 0.6 AKAs. Selective perfusion of preoperatively identified segmental artery-AKAs was performed in 11 cases. The average number of reconstructed segmental arteries was 0.5 in descending aortic aneurysms and 1.7 in thoracoabdominal aortic aneurysms. Although paraparesis occurred in two patients (5%), the remaining 35 patients did not suffer spinal cord injury. CONCLUSIONS Intraarterial computed tomographic angiography reliably identifies the segmental-AKA. Furthermore, selective perfusion of the segmental artery-AKA, based on accurate preoperative identification, might be one option for preventing intraoperative spinal cord ischemia.

Arterial spin-labeling MR imaging of cerebral hemorrhages.

IntroductionThe purpose of this study is to identify the characteristics of brain perfusion measured by arterial spin-labeling magnetic resonance imaging (ASL-MRI) in cerebral hemorrhages.MethodsBrain blood flow values (CBF-ASL values) for cerebral and cerebellar hemispheres and segmented cerebral regions were measured by ASL-MRI in 19 putaminal hemorrhage patients and 20 thalamic hemorrhage patients in acute or subacute stages. We assessed the lateralities of CBF-ASL values and the relationships between CBF-ASL values and other imaging findings and clinical manifestations.ResultsBoth the 19 putaminal hemorrhage patients and the 20 thalamic hemorrhage patients had significantly low CBF-ASL values of the contralateral cerebellum in subacute stage, suggesting that ASL-MRI might delineate crossed cerebellar diaschisis (CCD). Ipsilateral low CBF-ASL values were observed in frontal lobes and thalami with a putaminal hemorrhage and lentiform nuclei, temporal lobes, and parietal lobes with a thalamic hemorrhage, suggesting that ASL-MRI showed the ipsilateral cerebral diaschisis (ICD). In the putaminal hemorrhage patients, the hematoma volume negatively affected both the bilateral cerebellar and cerebral hemispheric CBF-ASL values. In the thalamic hemorrhage patients, a concomitant intraventricular hemorrhage caused low cerebral hemispheric CBF-ASL values.ConclusionThe use of ASL-MRI is sensitive to the perfusion abnormalities and could thus be helpful to estimate functional abnormalities in cerebral hemorrhage patients.

A hepatocellular neoplasm accompanied with massive histiocyte infiltration

This report presents the case of a unique hepatocellular nodule occurring in a 73-year-old Japanese male with diabetes mellitus and mild obesity. The nodule consisted of hepatocyte-like tumor cells and abundant foam cell type histiocytes that filled up a sinusoid-like space and formed central loose fibrosis. The superficial area did not contain as many histiocytes and showed hepatocellular adenoma character, but there was a focal hepatocellular carcinoma-like lesion, thus suggesting hepatocellular adenoma with malignant transformation. The background liver showed an almost normal histology except for mild steatosis with no specific infiltration of macrophages. These macrophages contained abundant fat droplets, whereas the tumor cells had no fat droplets. The expressions of monocyte chemoattractant protein-1 and macrophage colony-stimulating factor were significantly higher in the tumor than in the background liver. These findings suggested such macrophage infiltration induced by the tumor cells and these macrophages probably phagocytosed surplus fat at the intercellular space of this unique tumor.

Current Status and Problems of T790M Detection, a Molecular Biomarker of Acquired Resistance to EGFR Tyrosine Kinase Inhibitors, with Liquid Biopsy and Re-biopsy

Background/Aim: The purpose of this study was to consider appropriate application of liquid and re-biopsy through analysis of current status in practice. Patients and Methods: We performed a retrospective analysis of 22 patients with epidermal growth factor receptor (EGFR) mutation-positive non-small cell lung cancer who exhibited 1st/2nd generation EGFR-tyrosine kinase inhibitors resistance. The cobas® method was used to detect T790M with re-biopsy and the mutation-biased PCR and quenched probe method was used with liquid biopsy. Results: T790M detection rate was 52% with re-biopsy and 58% with liquid biopsy. The concordance between tissue and plasma was 58%. One patient who was T790M-positive with liquid biopsy showed heterogeneity among metastatic lesions in terms of osimertinib efficacy, as revealed by T790M detection with re-biopsy. Conclusion: Liquid biopsy reflects the whole body, whereas re-biopsy is useful for spatial diagnosis. Considering these characteristics, a combination of liquid and re-biopsy contribute to enhanced treatment.

Oral ulceration: an unusual manifestation of lymphomatoid granulomatosis

Dear Editor, Lymphomatoid granulomatosis (LYG) is a rare angiocentric and angiodestructive lymphoproliferative disorder (LPD) caused by latent Epstein-Barr virus (EBV) reactivation in immunosuppressed individuals [1]. Methotrexate (MTX) has been associated with the development of LPDs. In contrast to pulmonary involvement occurring in > 90% patients with LYG, involvement of oral cavity is extremely rare [2, 3]. We report two cases of oral cavity ulceration as an initial clinical manifestation of LYG.

A Technical Perspective for Understanding Quantitative Arterial Spin-labeling MR Imaging using Q2TIPS

We illustrate the fundamental theoretical principles of arterial spin-labeling (ASL) magnetic resonance imaging (MRI) and show a system that employs the second version of quantitative imaging of perfusion using a single subtraction (Q2TIPS) to quantify cerebral blood flow (CBF). We also discuss the effects of the parameters used in Q2TIPS on CBF values as measured with ASL-MRI.

Retrospective analysis of contrast-enhanced computed tomographic findings related to obstructive shock due to ascending aortic dissection.

Objective The objective of this study was to evaluate contrastenhanced computed tomography findings related to obstructive shock due to ascending aortic dissection (AAD). Methods The computed tomography findings in 9 AAD patients with shock, 11 AAD patients without shock, and 18 control subjects were evaluated for (1) pericardial effusion, (2) diameter of the inferior vena cava, (3) periportal hypodensity, (4) retrograde reflux of contrast material, (5) aortic and visceral enhancement, and (6) other factors (peripancreatic edema, bowel thickening/dilatation). Results Patients with shock showed the highest ratio of pericardial effusion, periportal hypodensity, and retrograde reflux of contrast material; largest inferior vena cava diameter; stronger aortic enhancement in both the arterial and portal phases; lowered splenic and pancreatic enhancement in the arterial phase; and stronger visceral (especially adrenal) enhancement, except for the renal medulla in the portal phase. Conclusions Computed tomography findings related to obstructive shock due to AAD reflected impaired diastolic filling, decreased cardiac output, and flow redistribution in visceral organs.