Masashi Shimizu

Role of diffusion-weighted echo-planar MRI in distinguishing between brain abscess and tumour: a preliminary report

Abstract Our purpose was to evaluate diffusion-weighted (DW) echo-planar MRI in differentiating between brain abscess and tumour. We examined two patients with surgically confirmed pyogenic brain abscess and 18 with metastatic brain tumours or high-grade glioma, using a 1.5 T system. The apparent diffusion coefficient (ADC) of each necrotic or solid contrast-enhancing lesion was measured with two different b values (20 and 1200 s/mm2). All capsule-stage brain abscesses (4 lesions) and zones of cerebritis (2 lesions) were identified on high-b-value DWI as markedly high-signal areas of decreased ADC (range, 0.58–0.70 [(10–3 mm2/s; mean, 0.63)]). All cystic or necrotic portions of brain tumours (14 lesions) were identified on high-b-value DWI as low-signal areas of increased ADC (range, 2.20–3.20 [(10–3 mm2/s; mean, 2.70)]). Solid, contrast-enhancing portions of brain tumours (19 lesions) were identified on high-b-value DWI as high-signal areas of sightly decreased or increased ADC (range, 0.77–1.29 [(10–3 mm2/s; mean, 0.94)]). Our preliminary results indicate that DW echo-planar MRI be used for distinguishing between brain abscess and tumour.

Positron emission tomography for predicting malignancy of sinonasal inverted papilloma.

Background: Sinonasal inverted papilloma (IP) is an uncommon nasal tumor. It is known for being locally invasive and recurrent, with a high probability of malignant transformation. Accurate initial staging and close surveillance are critical in the management of the disease. Methods and Results: Fluorine-18 fluorodeoxyglucose positron emission tomography (FDG PET) was performed in 5 patients with IP. High FDG uptake (maximum standardized uptake (SUVmax) value >3.0) was observed in all patients, and 2 patients with IP associated with squamous cell carcinoma (SCC) exhibited higher SUVmax values. Conclusion: The SUVmax value of a sinonasal tumor can warn the surgeon of the probability of an associated malignancy, even when preoperative biopsy demonstrates a purely benign papilloma.

Basilar artery migraine: reversible ischemia demonstrated by Tc-99m HMPAO brain SPECT

The authors present a case of basilar artery migraine in a 33-year-old woman who was initially misdiagnosed as having a cerebrovascular or mental disorder and subjected to MRI and cerebral angiography, which, however, did not show any pathologic findings. During admission to the university hospital, she lost consciousness. An emergency Tc-99m HMPAO brain SPECT showed a significant decrease of regional cerebral blood flow in the right temporal and occipital cortices, and right cerebellar hemisphere, where regional cerebral blood flow was decreased by 10–24% as compared to the left side. The second brain SPECT during a symptom-free phase showed the reversion of regional cerebral blood flow to normal in these areas. Basilar artery migraine was diagnosed by the finding of reversible ischemia in the territory of the right basilar artery on brain SPECT images and the clinical picture.

Diffusion-weighted echo-planar MRI of lacunar infarcts.

Abstract We studied 35 patients with lacunar infarcts, using diffusion-weighted echo-planar imaging (DW-EPI) at 1.5 T. The relative apparent diffusion coefficient ratio (ADCR) of each lesion was calculated and lesion conspicuity on DW-EPI was compared to that on images aquired with fast fluid-attenuated inversion recovery and T2-weighted fast spin-echo sequences. Acute small infarcts (within 3 days) were identified with DW-EPI as an area of decreased ADCR (range 0.33–0.87; mean 0.67) and high signal, subacute small infarcts (4–30 days) as a high-signal or isointense areas of decreased or nearly normal ADCR (0.54–0.98; 0.73), and chronic small infarcts (> 30 days) as low- or high-signal areas of nearly normal or increased ADCR (0.97–1.92; 1.32). In three patients, small infarcts of the brain stem in the hyperacute phase (within 6 h) were seen only with DW-EPI. In five patients, fresh small infarcts adjacent to multiple old infarcts could be distinguished only with DW-EPI.

Dural arteriovenous fistula involving the transverse sigmoid sinus after treatment: assessment with magnetic resonance digital subtraction angiography

IntroductionThe purpose of this study was to evaluate the utility of magnetic resonance digital subtraction angiography (MRDSA) in showing the presence or absence of retrograde venous drainage (RVD) in patients with intracranial dural arteriovenous fistula (DAVF) involving the transverse sigmoid sinus (TSS) after treatment.MethodsOf 16 patients with DAVF involving the TSS, 13 underwent digital subtraction angiography (DSA) and MRDSA before and after treatment, and 3 underwent DSA before treatment and DSA and MRDSA after treatment. Five patients underwent these procedures twice after treatment. A total of 21 examinations after treatment were evaluated retrospectively. The presence or absence of DAVF and RVD was decided on the basis of the DSA findings. Two neuroradiologists reviewed the MRDSA findings concerning the presence or absence of DAVF and RVD.ResultsDSA showed residual DAVF in 9 and residual RVD in 5 of 21 examinations. MRDSA revealed residual DAVF in 8 of 21 examinations. MRDSA did not show residual DAVF in one examination because of a very small (low-flow) residual DAVF without RVD. MRDSA identified residual RVD in 5 of 21 examinations. MRDSA was completely consistent with DSA concerning the presence or absence of residual RVD.ConclusionMRDSA could evaluate the presence or absence of RVD in patients with DAVF involving TSS after treatment. MRDSA may give reliable information as to whether patients with DAVF involving the TSS should undergo additional DSA after treatment.

FDG-PET imaging in duodenal cancer

F-18 fluorodeoxyglucose positron emission tomography (FDG-PET) imaging is a useful modality in the detection of various tumors, including colon cancer and gastric cancer. We evaluated a patient with duodenal cancer with multiple metastases including brain metastases using FDG-PET imaging. It revealed multiple tumor uptake in the brain, clavicular fossa, mediastinum, right adrenal gland and duodenum. These results suggest that FDG-PET imaging may be useful in detecting the primary and metastatic lesions of duodenal adenocarcinoma.

Extensive soft-tissue involvement of dermatomyositis detected by whole-body scintigraphy with99mTc-MDP and201Tl-chloride

The authors present a case of extensive soft-tissue radioactivity visualized on both99mTc-MDP and201Tl-chloride scintigrams in a patient with dermatomyositis and colon cancer. Incidentally, diffuse and intense uptake of99mTc-MDP was observed in the shoulder girdles, anterior chest wall, psoas muscles, both proximal thighs and right lower limb, corresponding to the sites of symptomatic muscles, even though skin lesions were limited and no calcification was detected on radiographs. Moreover,201Tl-chloride was also intensely accumulated in nearly the same sites as the symptomatic muscles as shown on the99mTc-MDP bone scintigrams.Whole-body scintigraphy with99mTc-MDP and201Tl-chloride is a useful tool to detect occult muscle lesions with dystrophic calcification and hyperemia in dermatomyositis.

Cardiac sympathetic denervationmodulates the sympathoexcitatoryresponse to acute myocardial ischemia

Abstract Objectives This study was designed to elucidate the influence of cardiac sympathetic denervation on the sympathoexcitatory response to acute myocardial ischemia during balloon coronary occlusion (BCO) in humans. Background Alterations of cardiac sympathetic nerve function could modulate sympathetic reflexes originating from the ischemic area. Methods In 23 patients with angina pectoris, we quantified the baseline cardiac sympathetic denervation of the ischemia-related area by iodine-123 metaiodobenzylguanidine (123I-MIBG), and transient changes in sympathetic activity during BCO by wavelet analysis of RR interval variability. Results Balloon coronary occlusion resulted in a transient augmentation of low-frequency (LF: 0.04 to 0.14 Hz) spectral components of RR interval variability in 4 of 12 patients with cardiac denervation and in 8 of 11 patients without denervation (p Conclusions These findings suggest that if the provoked ischemia is not severe, cardiac sympathetic denervation could prevent ischemia-induced sympathoexcitation.

Sequential subtraction scintigraphy with99mTc-RBC for the early detection of gastrointestinal bleeding

To improve the early detectability of gastrointestinal (GI) bleeding, we have developed a new subtraction scintigraphic technique usingin vivo labeled99mTc red blood cells (RBC). Use of this new sequential subtraction method every 5 min makes it possible to detect early the bleeding site and calculate the bleeding rate. In phantom experiments, focal activity was detected on subtraction images at pump rates of more than 0.20 ml/min at any urethane thickness, but was negative on conventional scintigrams. The calculated pump rate by the subtraction method correlated well with the actual syringe pump rate (y = 1.07x-0.02, r = 0.99, p < 0.01) in the case of an 8-cm urethane board as an abdominal wall. Twenty-four of 50 patients with suspected GI bleeding were confirmed to be positive within 24 hr. The subtraction method showed 15 true positive and 2 false positive cases within 60 min. On the other hand, the conventional scintigraphic method showed only 7 true positive and 1 false positive cases. Sensitivity of the subtraction method was 62.5%, which was significantly higher (p < 0.05) than that of the conventional scintigraphic method (29.2%).These results suggest that sequential subtraction scintigraphy with99mTc-RBC is an effective method for the early detection of GI bleeding and shortening the examination time as compared with conventional scintigraphy.

A case of retroperitoneal extramedullary plasmacytoma with multiple metastases

We investigated a patient with extramedullary plasmacytoma in the retroperitoneal space with multiple metastases using abdominal CT scan and 67Ga scintigraphy. Abdominal enhanced CT revealed the retroperitoneal tumor mimicking lymphoma. 67Ga scintigraphy showed multiple tumor localization. We could detect retroperitoneal extramedullary plasmacytoma with multiple metastases using 67Ga scintigraphy. This retroperitoneal tumor may appear similar to lymphoma on CT.