Motoo Nakagawa

Thoracic hemangiomas: imaging via CT, MR, and PET along with pathologic correlation.

Purpose To characterize the imaging features of thoracic hemangioma, including findings on computed tomography (CT), magnetic resonance imaging (MRI), and positron emission tomography (PET) using 18F-fluoro-2-deoxy-D-glucose (FDG). Methods Six patients with thoracic wall hemangioma and 2 patients with mediastinal hemangioma were included in this study. Preoperative evaluation was performed using CT (n=7), MRI (n=8), and FDG-PET (n=2). Five cases were pathologically confirmed by surgery and the remaining 3 cases were diagnosed clinically. Results On CT, characteristic finding of phleboliths were depicted in 5 of 7 cases (71%). Fat component was demonstrated in 3 of 7 cases with CT (3/7—43%) and 5 of 8 cases with MRI (5/8—63%). On MRI, characteristic finding of high intensity on T2-weighted images was demonstrated in all 8 cases and the high signal intensity was emphasized in all 4 cases on fat-suppression T2-weighted images. Both of two PET scans showed mildly elevated accumulation of FDG. Conclusions Phleboliths, fat component, and high intensity on T2-weighted and fat-suppression T2-weighted image were thought to be characteristic findings reflecting the histologic findings. It might be useful to recognize these findings for differentiating hemangiomas from other soft tissue tumors, particularly malignant neoplasms.

Reperfusion Rates of Pulmonary Arteriovenous Malformations after Coil Embolization: Evaluation with Time-Resolved MR Angiography or Pulmonary Angiography

PURPOSE To assess reperfusion rates after coil embolization for pulmonary arteriovenous malformations (PAVMs) using time-resolved magnetic resonance (MR) angiography or pulmonary angiography. MATERIALS AND METHODS Patients with PAVMs who underwent embolization and met the following inclusion criteria were included: (a) embolization was performed using bare or fibered platinum microcoils or both, (b) the complete cessation of flow was confirmed by digital subtraction angiography, and (c) follow-up examinations were conducted with time-resolved MR angiography or pulmonary angiography. Coil embolization was performed in 16 patients with 24 untreated or reperfused PAVMs. Sac embolization was performed for 12 untreated PAVMs. Feeding artery embolization was performed as primary embolization in each of the 12 reperfused PAVMs. Five PAVMs were treated 2 to 4 times because of reperfusion. The study included 32 coil embolizations. Follow-up images were reviewed, and reperfusion rates were assessed. The relationships between reperfusion and the location of PAVM, size of PAVM (feeding artery and venous sac), coils (number and total length), timing of embolization (primary or repeat embolization), and types of coils used (with or without fibered coils) were examined. RESULTS Reperfusion rates at 3, 6, 12, and 24 months were 8%, 27%, 36%, and 49%, respectively, for the 12 untreated PAVMs (primary embolization) and 50%, 50%, 92%, and 100%, respectively, for the 12 reperfused PAVMs (repeat embolization) (P = .0062). No significant differences were observed in the other parameters measured. CONCLUSIONS When evaluated with time-resolved MR angiography or pulmonary angiography, reperfusion rates after coil embolization for PAVM were considerably high, particularly with repeat embolization.

Diagnostic Accuracy of 18F-2-deoxy-fluoro-D-glucose Positron Emission Tomography for pN1 Lymph Nodes in Patients with Lung Cancer

Background: The accuracy of 18F-2-deoxy-fluoro-D-glucose positron emission tomography (FDG-PET) for diagnosing nodal status in patients with lung cancer was initially reported as excellent, but, with increasing experience, the problem of false-positive and false-negative assessments has been observed. Purpose: To evaluate the accuracy of FDG-PET for diagnosing nodal status in lung cancer patients with pathologically proven N2 lymph nodes and compare it with that of computed tomography (CT). Material and Methods: Nineteen pN2 patients (13 males and six females) with primary lung cancer undergoing preoperative CT and FDG-PET were investigated. Lymph nodes were considered to be positive when uptake higher than the surrounding mediastinal level was visually observed. Slight symmetrical mediastinal uptake was considered to be negative, representing benign physiological accumulation. Radiological and pathological correlation was investigated, and the association between FDG accumulation and the size of metastatic lymph nodes and metastatic lesions was evaluated. Results: Of the 19 patients, nodal stage determined by using FDG-PET was cN0 in four (21%) cases, cN1 in three (16%), cN2 in nine (47%), and cN3 in three (16%). On CT, nodal stage was cN0 in three (16%) cases, cN1 in seven (37%), cN2 in eight (42%), and cN3 in one (5%). Thus, FDG-PET provided correct N-staging in 47%, under-staging in 37%, and overstaging in 16%. CT staging was correct in 42%, underestimated in 53%, and overestimated in 5%. The maximum area of metastatic foci was 15.8 ±21.3 mm2 (mean ± SD) in false-negative nodes and 75.0±56.3 mm2 in true-positive nodes (P<0.0001). Conclusion: Diagnostic accuracy of FDG-PET (47%) was low and similar to that of CT (42%). The possibility of false-negative as well as false-positive findings should be recognized in interpreting PET images. Micrometastasis appeared to be the greatest cause of false-negative findings.

Clinical usefulness of the triaxial system in super-selective transcatheter arterial chemoembolization for hepatocellular carcinoma

Background Transcatheter arterial chemoembolization (TACE) has been widely performed for inoperable hepatocellular carcinoma (HCC). Super-selective TACE is preferable to non-selective therapy and it is important to advance the catheter tip as close to the tumor as possible in the feeding artery. A new microcatheter with a 1.9-Fr non-tapered tip has recently become available and this new microcatheter can be inserted into a 2.7-Fr. microcatheter. It is called the triple co-axial (triaxial) system. Purpose To evaluate the clinical usefulness of super-selective TACE for HCC using the triaxial system. Material and Methods We evaluated 63 HCCs that underwent super-selective TACE. Requirements for inclusion in this study were: (a) HCCs 3 cm or less in diameter; (b) TACE performed by a single operator; and (c) no additional treatment in the absence of local progression. All patients were followed for more than 1 year after TACE. The median follow-up period for surviving patients was 20 months (range, 17–31 months). The conventional system was used in 35 HCCs (control group), and the triaxial system was used in 28 (triaxial group). We reviewed angiographies at TACE and follow-up CT, and then evaluated local tumor status in the two groups. Results Local tumor control rates at 3, 6, and 18 months were 64%, 36%, and 29%, respectively, in the triaxial group, and 40%, 14%, and 8.6%, respectively, in the control group (P = 0.0086). There were no major complications in either group. Conclusion The triaxial system appears to be useful for super-selective TACE and may contribute to achieving higher local control rates for HCC.

Brain atrophy caused by vitamin B12-deficient anemia in an infant.

Vitamin B12 deficiency in infants often presents with nonspecific hematological, gastrointestinal, and neurological manifestations. It is usually caused by inadequate intake, abnormal absorption, or congenital disorders of vitamin B12 metabolism, including transport disorders. We describe a vitamin B12-deficient infant with severe anemia who was breastfed. His mother had undiagnosed vitamin B12 deficiency having undergone total gastrectomy 18 years earlier. The infant developed normally after taking vitamin B12. It is important to suspect vitamin B12 deficiency in mothers who have undergone gastrectomy. Early diagnosis and treatment of vitamin B12 deficiency in infants is important and will help improve long-term prognosis.

MRI findings in fetuses with an abdominal wall defect: gastroschisis, omphalocele, and cloacal exstrophy

Congenital abdominal wall defects include several entities such as gastroschisis, omphalocele, and cloacal exstrophy. It is important for perinatal management and parental counseling to understand the magnetic resonance (MR) imaging features essential for correctly diagnosing the clinical condition and predicting the prognosis of fetal patients. The purpose of this pictorial review is to demonstrate the MR imaging features of fetal cases with an abdominal wall defect and the pitfalls of image findings.

Volume of Interest Analysis of Spatially Normalized PRESTO Imaging to Differentiate between Parkinson Disease and Atypical Parkinsonian Syndrome

Purpose: Various magnetic resonance imaging (MRI) techniques including T2*-weighted imaging, susceptibility-weighted imaging, and MR relaxometry had been performed to evaluate different patterns of brain iron depositions in Parkinsonian syndrome. The aim of the present study was to evaluate the diagnostic value of a volume of interest (VOI) analysis on the principles of echo shifting with a train of observations (PRESTO) imaging using the statistical parametric mapping (SPM) 8 and the WFU PickAtlas program for the diagnosis of Parkinsonian syndrome. Methods: Fifty subjects, including 13 with the Parkinsonian variant of multiple system atrophy (MSA-P), 12 with progressive supranuclear palsy (PSP), 12 with Parkinson’s disease (PD) and 13 controls were evaluated in this study. After the spatial normalization of PRESTO images on SPM8, the WFU PickAtlas program was performed to create target VOIs in the putamen, red nucleus, substantia nigra, subthalamic nucleus, and dentate nucleus. The signal intensity ratio (SIR) was calculated by normalizing the signal of each VOI to that of the cerebrospinal fluid space. These SIRs were used as determinants in receiver operating characteristic (ROC) analyses. Results: SIR of the putamen was significantly lower in MSA-P than in PSP (P = 0.0051) and controls (P = 0.0004). In contrast, SIR of the red nucleus was significantly lower in PSP than in MSA-P (P = 0.0003), PD (P = 0.0029), and controls (P = 0.0011). In ROC analyses, SIR of the putamen exhibited the highest areas under the curves (AUCs) of 0.83 (vs. PSP) and 0.91 (vs. controls) in the diagnosis of MSA-P. On the other hand, SIR of the red nucleus exhibited the highest AUCs of 0.87 (vs. MSA-P), 0.90 (vs. PD), and 0.89 (vs. controls) in the diagnosis of PSP. Conclusions: The VOI analysis based on spatially normalized PRESTO images may be useful for depicting hypointensity, indicative of abnormal iron depositions, of the putamen and red nucleus in the diagnosis of MSA-P and PSP.

CT findings of bronchial glandular papilloma.

Solitary pulmonary papillomas are rare benign tumors in adults. Glandular papilloma is the rarest subtype among them. In this report, we describe a case of glandular papilloma that showed unique computed tomography features. It was a round nodule containing air spaces encapsulated with a smooth and thin wall, which suggested its endobronchial origin and a secondary change owing to air trapping.

A combination of genetic and biochemical analyses for the diagnosis of PI3K-AKT-mTOR pathway-associated megalencephaly

BackgroundConstitutive activation of the PI3K-AKT-mTOR pathway (mTOR pathway) underlies megalencephaly in many patients. Yet, prevalence of the involvement of the PI3K-AKT-mTOR pathway in patients with megalencephaly remains to be elucidated, and molecular diagnosis is challenging. Here, we have successfully established a combination of genetic and biochemical methods for diagnosis of mTOR pathway-associated megalencephaly, and have attempted to delineate the clinical characteristics of the disorder.MethodsThirteen patients with an increased head circumference and neurological symptoms participated in the study. To evaluate the activation of the mTOR pathway, we performed western blot analysis to determine the expression levels of phosphorylated S6 ribosomal protein (phospho-S6 protein) in lymphoblastoid cell lines from 12 patients. Multiplex targeted sequencing analysis for 15 genes involved in the mTOR pathway was performed on 12 patients, and whole-exome sequencing was performed on one additional patient. Clinical features and MRI findings were also investigated.ResultsWe identified pathogenic mutations in six (AKT3, 1 patient; PIK3R2, 2 patients; PTEN, 3 patients) of the 13 patients. Increased expression of phospho-S6 protein was demonstrated in all five mutation-positive patients in whom western blotting was performed, as well as in three mutation-negative patients. Developmental delay, dysmorphic facial features were observed in almost all patients. Syndactyly/polydactyly and capillary malformations were not observed, even in patients with AKT3 or PIK3R2 mutations. There were no common phenotypes or MRI findings among these patients.ConclusionsA combination of genetic and biochemical methods successfully identified mTOR pathway involvement in nine of 13 (approximately 70%) patients with megalencephaly, indicating a major contribution of the pathway to the pathogenesis of megalencephaly. Our combined approach could be useful to identify patients who are suitable for future clinical trials using an mTOR inhibitor.

Nodular thymic lymphoid follicular hyperplasia mimicking thymoma

In this report, we describe a case of thymic lymphoid follicular hyperplasia that was incidentally found as a small thymic nodule in the health screening program including a low-dose chest CT. The CT and MRI findings of the nodule were similar to those of thymoma, and it was difficult to differentiate the lesion from thymoma.