Shinsuke Kyogoku

Cervical spondylosis: Evaluation of microstructural changes in spinal cord white matter and gray matter by diffusional kurtosis imaging

INTRODUCTION We investigated microstructural changes in the spinal cord, separately for white matter and gray matter, in patients with cervical spondylosis by using diffusional kurtosis imaging (DKI). METHODS We studied 13 consecutive patients with cervical myelopathy (15 affected sides and 11 unaffected sides). After conventional magnetic resonance (MR) imaging, DKI data were acquired by using a 3T MR imaging scanner. Values for fractional anisotropy (FA), apparent diffusion coefficient (ADC), and mean diffusional kurtosis (MK) were calculated and compared between unaffected and affected spinal cords, separately for white matter and gray matter. RESULTS Tract-specific analysis of white matter in the lateral funiculus showed no statistical differences between the affected and unaffected sides. In gray matter, only MK was significantly lower in the affected spinal cords than in unaffected spinal cords (0.60±0.18 vs. 0.73±0.13, P=0.0005, Wilcoxons signed rank test). CONCLUSIONS MK values in the spinal cord may reflect microstructural changes and gray matter damage and can potentially provide more information beyond that obtained with conventional diffusion metrics.

Stabilization of a Percutaneously Implanted Port Catheter System for Hepatic Artery Chemotherapy Infusion

A port catheter system for hepatic artery infusion chemotherapy was implanted percutaneously via the left subclavian artery in 41 patients for treatment of unresectable liver metastases. The catheter tip was inserted into the gastroduodenal artery (GDA), the end hole was occluded with a guidewire fragment, and a side-hole for infusion was positioned at the bifurcation of the proper hepatic artery and the GDA. The GDA was embolized with steel coils around the infusion catheter tip via a transfemoral catheter. This procedure is designed to reduce the incidence of hepatic artery occlusion and infusion catheter dislocation.

Spontaneous intracranial hypotension: characteristic findings of radionuclide cisternography using In-111 DTPA

The authors describe two patients with spontaneous intracranial hypotension. The patients had the cardinal features of a postural headache. In both patients, radionuclide cisternography revealed cerebrospinal fluid (CSF) leakage at the cervicothoracic junction and early accumulation of isotope in the urinary tract. Postmyelography CT scans showed no underlying structural abnormalities. Both patients were treated successfully by intravenous infusion of low-osmolarity fluid. Radionuclide cisternography obtained after treatment in one of the patients showed that the CSF leak had disappeared. Radionuclide cisternography enabled the causes of spontaneous intracranial hypotension to be differentiated and visualized the sites of CSF leakage. It was also useful for evaluating changes in a CSF leak after treatment. FIGURE 1 FIGURE 2

Multiple sclerosis: Benefits of q-space imaging in evaluation of normal-appearing and periplaque white matter

INTRODUCTION Diffusion tensor imaging (DTI) reveals white matter pathology in patients with multiple sclerosis (MS). A recent non-Gaussian diffusion imaging technique, q-space imaging (QSI), may provide several advantages over conventional MRI techniques in regard to in vivo evaluation of the disease process in patients with MS. The purpose of this study is to investigate the use of root mean square displacement (RMSD) derived from QSI data to characterize plaques, periplaque white matter (PWM), and normal-appearing white matter (NAWM) in patients with MS. METHODS We generated apparent diffusion coefficient (ADC) and fractional anisotropy (FA) maps by using conventional DTI data from 21 MS patients; we generated RMSD maps by using QSI data from these patients. We used the Steel-Dwass test to compare the diffusion metrics of regions of interest in plaques, PWM, and NAWM. RESULTS ADC differed (P<0.05) between plaques and PWM and between plaques and NAWM. FA differed (P<0.05) between plaques and NAWM. RMSD differed (P<0.05) between plaques and PWM, plaques and NAWM, and PWM and NAWM. CONCLUSION RMSD values from QSI may reflect microstructural changes and white-matter damage in patients with MS with higher sensitivity than do conventional ADC and FA values.

Intersite Reliability of Diffusion Tensor Imaging on Two 3T Scanners

We report the intersite scan reliability of diffusion tensor imaging (DTI) parameters using identical 3T scanners and acquisition protocols at 2 sites. Voxel-based analysis revealed several regions with significant intersite differences. The intersite reliability of DTI measures showed coefficients of variation below 4% in tract-specific analysis (TSA) and below 6% in atlas-based analysis. Given the excellent reliability of TSA, our results suggest it as a promising and useful tool for multicenter DTI studies.

Emphysematous pyelonephritis— conversion of type i to type II appearance on serial CT studies

Recently, emphysematous pyelonephritis (EPN) has been classified into two subtypes based on CT findings. We recently experienced a patient whose CT image changed from type I (extensive destruction of the renal parenchyma with a large amount of air density without any fluid collection) to type II (containing a large amount of fluid) during the course of conservative treatment. We believe that some patients with type I EPN can change to type II EPN.

Alterations of the optic pathway between unilateral and bilateral optic nerve damage in multiple sclerosis as revealed by the combined use of advanced diffusion kurtosis imaging and visual evoked potentials

OBJECTIVES We investigated changes in the optic tract and optic radiation in patients with multiple sclerosis (MS) by comparing unilateral and bilateral optic nerve damage assessed based on visual evoked potentials (VEPs) using advanced diffusion MR metrics. METHODS In 21 MS patients, diffusion MRI was performed. Maps of fractional anisotropy, apparent diffusion coefficient (ADC), and mean kurtosis (MK) were computed. On the basis of the P100 latency in VEPs, the MS patients were divided into three groups: bilateral (n=7), unilateral (n=7), and no abnormality (n=7). Their optic tracts and optic radiations were analyzed with diffusion MRI-based fiber tracking. We also investigated the correlations between diffusion parameters and VEPs (n=21). RESULTS In the optic tract, the diffusion changes in each of the three groups showed step-like changes. The diffusion changes in the optic radiations of the unilateral group were similar to those in the normal VEP group. Only the bilateral group showed significantly higher ADC and lower MK relative to the other two groups (P<0.05, Steel-Dwass multiple-comparison test). A significant positive correlation between VEP latency and ADC and a significant negative correlation between VEP latency and MK were observed (P<0.01, Spearmans correction). CONCLUSIONS We first evaluated the relationship between VEPs and DKI and concluded that the lateral geniculate nucleus may compensate for unilateral damage in the pre-geniculate optic pathway via neural plasticity.

Paratesticular aggressive fibromatosis: CT findings

Aggressive fibromatoses commonly originate from the musculoskeletal system, mesentery, and retroperitoneum. We report a case of aggressive fibromatosis arising from the spermatic cord. On helical computed tomography, the lesion appeared as a solid mass with well-defined borders in the scrotum and with infiltrative features in the retroperitoneum.

Usefulness of thallium-201 SPECT imaging for the evaluation of local recurrence of colorectal cancer

PurposeTo clarify the accumulation of thallium-201 in recurrent tumors in patients who had undergone resection of colorectal cancer and to evaluate the usefulness of thallium-201 single photon emission computed tomography (SPECT) images for distinguishing recurrent tumors from postoperative changes.Materials and MethodsThallium-201 SPECT images and CT images of 22 consecutive patients suspected to have local recurrence of colorectal cancer based on clinical symptoms and signs were reviewed. CT was performed on all patients.ResultsIn nine of the 11 patients who had local recurrence, SPECT images showed positive thallium uptake, but in 10 of the 11 patients confirmed to have no recurrence, SPECT images showed negative thallium uptake. Sensitivity was 81.8% (9/11) specificity was 90.9% (10/11), and accuracy was 86.4% (19/22). There were five patients in whom CT results were inconclusive. All of them had rectal cancer and had undergone Miles’ operation, and all were correctly diagnosed by thallium-201 SPECT.ConclusionThallium-201 exhibited intense uptake in recurrent colorectal cancer. Thallium-201 SPECT is considered to be a useful diagnostic tool for the detection of recurrence of colorectal cancer, particularly in patients with inconclusive CT results.

Embolization of spontaneous intratumoral hemorrhage with the hemodynamic characteristics of arteriovenous fistula in renal angiomyolipoma.

Aneurysms within renal angiomyolipomas (AML) may rupture into the tumor or pararenal space. Transcatheter arterial embolization is the first-choice treatment to control bleeding. Here, we describe the use of coil embolization in two cases of spontaneous intratumoral hemorrhage with the hemodynamic characteristics of renal arteriovenous (AV) fistula in renal AML. In case 1, renal angiography showed several intratumoral aneurysms, one of which had ruptured into the tumor, resulting in the formation of an intratumoral hematoma. Blood flow within the hematoma was rapid and the blood was immediately returned to the systemic circulation through the left renal vein. In case 2, renal angiography showed that the rupture of an intratumoral aneurysm of a tumor-feeding artery had resulted in formation of an intratumoral hematoma and direct renal vein communication. No extratumoral hemorrhage was observed in either case. The hemodynamics of both hematomas resembled those of a high-flow renal AV fistula. The ruptured aneurysms were embolized with detachable and pushable coils (case 1) or pushable coils only (case 2). To our knowledge, this is the first report of successful embolization of AV fistula-like intratumoral hemorrhage in renal AML.