Combined lie's type D and type A agenesis of the left internal carotid artery diagnosed by magnetic resonance angiography.

PURPOSE: To report an unusual case of combined Lie's types A and D of internal carotid artery (ICA) agenesis, diagnosed by magnetic resonance angiography (MRA). METHODS: A 60-year-old woman with dizziness underwent cranial magnetic resonance imaging (MRI) and MRA of the intracranial region for the evaluation of brain and vascular lesions. The magnetic resonance machine was a 3.0-T scanner. RESULTS: MRI showed no abnormalities, except for multiple small white matter lesions. MRA showed that the left ICA was absent, except for the supraclinoid segment, and an anastomotic vessel was present between the paraclinoid segments of the bilateral ICAs, indicating Lie's type D ICA agenesis. The left posterior communicating artery (PCoA) was also present. Thus, there were also features of type A ICA agenesis. The anastomotic vessels between the bilateral ICAs and ipsilateral PCoA were relatively small in caliber. CONCLUSION: Lie's type D ICA agenesis usually does not communicate with the anterior and posterior circulations. We encountered a case of combined type D and type A ICA agenesis. To our knowledge, no similar case has been reported in the English literature. This is the second case of type D ICA agenesis with patent ipsilateral PCoA. We speculate that in case of type A ICA agenesis, when the development of the PCoA is insufficient to support collateral blood flow, an anastomotic vessel between bilateral ICAs may develop.

Evaluation of organized thrombus in distal pulmonary arteries in patients with chronic thromboembolic pulmonary hypertension using cone-beam computed tomography.

PURPOSE: Balloon pulmonary angioplasty (BPA) is an emerging treatment for inoperable chronic thromboembolic pulmonary hypertension (CTEPH) patients. However, the approach to use to identify distal thrombi suitable for BPA has not yet been established. The purpose of this work was therefore to evaluate distal chronic thromboembolic lesions for BPA using cone-beam computed tomography (CBCT). MATERIALS AND METHODS: Thirty-two patients (men/women: 9/23) with CTEPH who underwent CBCT before BPA were enrolled. We assessed representative forms of chronic thromboembolic lesions in 94 segmental and/or 208 subsegmental branches according to CBCT and compared the results to the findings of selective angiography during BPA. RESULTS: We classified CTEPH lesions into five subtypes as follows: type 1a (11.1 %), webs; type 1b (14.4 %), web with severe narrowing of the subsegmental artery; type 2, (58.2 %) web and slits; type 3 (2.4 %), slits; and type 4 (13.9 %), pouch defect with incomplete obstruction of subsegmental branches or complete occlusion. In our study, 92.6 % of the CTEPH lesions diagnosed by CBCT were highly consistent with the findings of selective angiography during BPA. CONCLUSION: CBCT clearly revealed and classified distal lesions in CTEPH patients. The CBCT findings for distal lesions were highly consistent with those of selective angiography during BPA. CBCT could be a useful modality to detect target lesions before BPA.

Organized thrombus in pulmonary arteries in patients with chronic thromboembolic pulmonary hypertension; imaging with cone beam computed tomography.

PURPOSE: To assess the usefulness of cone-beam CT (CBCT) during pulmonary angiography for the evaluation of organized thrombus at segmental or subsegmental arteries in patients with chronic thromboembolic pulmonary hypertension (CTEPH). MATERIALS AND METHODS: The segmental and/or subsegmental pulmonary arteries of 13 patients with CTEPH were evaluated by CBCT. We classified representative forms of organized thrombus into 4 types (type 1: webs, type 2: web and slits, type 3: slits, and type 4: narrowing or complete occlusion), and the distribution and frequency of the organized thrombus were evaluated. The relative detectability of these lesions using CBCT was compared with that in contrast-enhanced CT pulmonary angiography (CTPA). RESULTS: Type 1 lesions were most frequently observed in both segmental (30/65 = 46 %) and subsegmental branches (72/156 = 46 %). Type 2 lesions were relatively less frequent than type 1, but subsegmental branches were frequently involved (29/156 = 19 %). Type 3 lesions observed as a thin flap in 9/156 subsegmental branches (6 %). Comparing with CTPA, all 40 lesions in segmental branches were detectable in CTPA, whereas only 62 lesions among 90 lesions (69 %) in subsegmental branches could be observed by CTPA. CONCLUSION: CBCT is found to be useful for the treatment planning of balloon pulmonary angioplasty distal to segmental arteries.

Interobserver agreement on the diagnosis of bowel ischemia: assessment using dynamic computed tomography of small bowel obstruction.

PURPOSE: The aim of this study was to evaluate the accuracy and interobserver variability of dynamic computed tomography (CT) for diagnosis of small bowel obstruction. METHOD AND MATERIALS: A total of 115 patients with a CT diagnosis of small bowel obstruction were included. Two radiologists and two residents performed blinded, independent, retrospective reviews of CT studies. Attention was focused on the presence of reduced early enhancement of the bowel wall and closed loop obstruction. Results were correlated with surgical findings in 15 cases and clinical follow-up in 100 cases. Sensitivity and specificity were calculated, and kappa statistics were used to analyze interobserver agreement. RESULTS: In all, 13 cases were surgically confirmed small bowel ischemia. Sensitivity, specificity, positive predictive value, and negative predictive value for the diagnosis of ischemia were 85%, 96%-97%, 73%-79%, and 97%-98%, respectively, for radiologists and 69%-93%, 93%-95%, 63%-64%, and 96%-99%, respectively, for residents. For agreement in the interpretations of reduced early enhancement of bowel wall, closed loop obstruction, and presence of bowel ischemia, the values were 0.62, 0.71, and 0.80, respectively, between radiologists and 0.57-0.70, 0.63-0.74, and 0.56-0.68, respectively, between radiologists and residents. CONCLUSION: There was moderate or substantial agreement for the diagnosis of small bowel ischemia between radiologists and residents. However, there was substantial agreement for the presence of closed loop obstruction.

Imaging analysis of the brain in a primate model of cerebral malaria.

This paper reviews our studies concerning imaging analysis of the brain in a primate model of cerebral malaria. To elucidate the clinical features of cerebral malaria, we performed positron emission tomography with (18)F-fluorodeoxyglucose (FDG-PET) scanning and magnetic resonance imaging (MRI) of the brain in Japanese macaques (Macaca fuscata) infected with Plasmodium coatneyi, a primate model of severe human malaria with cerebral involvement. On FDG-PET scanning, we observed diffuse and heterogeneous reduction of metabolism in the cerebral cortex in the acute phase of malaria infection. Although the monkey exhibited severe clinical signs, MR imaging did not reveal any significant changes during the course of infection. Histopathologic examination frequently revealed preferential sequestration of PRBCs in the cerebral and cerebellum capillaries, but neither parenchymal injury nor neuronal necrosis was found in the tissues. These results suggest that heterogeneous metabolic reduction and lack of abnormalities on MRI in the acute phase of CM may be due to any avoidance mechanisms from ischemia caused by sequestration. This may be one reason why more than half of CM patients have no neurological sequelae following recovery.

Enhancement of splenic glucose metabolism during acute malarial infection: correlation of findings of FDG-PET imaging with pathological changes in a primate model of severe human malaria.

In the current study, to elucidate the clinical features of severe malaria, we performed whole-body positron emission tomography (PET) with (18)F-fluorodeoxyglucose (FDG) of Plasmodium coatneyi-infected acute-phase Japanese macaques. The infected monkeys clearly exhibited increase in splenic FDG uptake indicating marked enhancement of glucose metabolism. The standardized uptake values (SUVs) of the spleen in the infected monkeys were significantly higher than those in the uninfected monkey. At autopsy, splenomegaly was clearly present in all infected monkeys, and histopathologic findings included hyperplasia of lymphoid follicles in white pulp, a large number of activated macrophage, and congestion of parasitized red blood cells (PRBCs) and malaria pigments in red pulp. We suggest that increase in splenic glucose uptake may thus be closely related to activation of splenic clearance system against blood-stage malarial parasites.

Cerebral metabolic reduction in severe malaria: fluorodeoxyglucose-positron emission tomography imaging in a primate model of severe human malaria with cerebral involvement.

Cerebral metabolic changes in Japanese macaques (Macaca fuscata) infected with Plasmodium coatneyi, a primate model of severe human malaria with cerebral involvement, were directly evaluated by fluorodeoxyglucose-positron emission tomography (FDG-PET). We observed diffuse and heterogeneous reduction of metabolism in the cerebral cortex in the acute phase of malaria infection. Neuropathologic examination showed preferential sequestration of parasitized red blood cells in the cerebral microvasculature. However, hemorrhagic change or necrosis was not observed in hematoxylin and eosin-stained and Nissl-stained brain tissues. This suggests that reduction of cerebral metabolism occurs before parenchymal changes appear in the brain. This may be one reason why more than half of the patients with cerebral malaria have no neurologic sequelae after recovery.