Regional reliability of quantitative signal targeting with alternating radiofrequency (STAR) labeling of arterial regions (QUASAR).

BACKGROUND AND PURPOSE: Quantitative signal targeting with alternating radiofrequency labeling of arterial regions (QUASAR) is a recent spin labeling technique that could improve the reliability of brain perfusion measurements. Although it is considered reliable for measuring gray matter as a whole, it has never been evaluated regionally. Here we assessed this regional reliability. METHODS: Using a 3-Tesla Philips Achieva whole-body system, we scanned four times 10 healthy volunteers, in two sessions 2 weeks apart, to obtain QUASAR images. We computed perfusion images and ran a voxel-based analysis within all brain structures. We also calculated mean regional cerebral blood flow (rCBF) within regions of interest configured for each arterial territory distribution. RESULTS: The mean CBF over whole gray matter was 37.74 with intraclass correlation coefficient (ICC) of .70. In white matter, it was 13.94 with an ICC of .30. Voxel-wise ICC and coefficient-of-variation maps showed relatively lower reliability in watershed areas and white matter especially in deeper white matter. The absolute mean rCBF values were consistent with the ones reported from PET, as was the relatively low variability in different feeding arteries. CONCLUSIONS: Thus, QUASAR reliability for regional perfusion is high within gray matter, but uncertain within white matter.

High-resolution magnetic resonance imaging of rotator cuff tears using a microscopy coil: noninvasive detection without intraarticular contrast material.

PURPOSE: The aim of this study was to evaluate the feasibility of high-resolution magnetic resonance imaging (MRI) using a microscopy coil for the diagnosis of rotator cuff tears by comparing the method to conventional MRI and MRI arthrography. MATERIALS AND METHODS: A total of 68 shoulders were prospectively studied using a 1.5-T MRI unit. Conventional MRI scans were obtained with a surface coil and high-resolution MRI scans with a microscopy coil. MRI arthrography was performed in 28 shoulders using a surface coil. MRI evaluation of tears of rotator cuff tendons was compared with arthroscopic findings and surgical results. RESULTS: The surgery revealed 40 full-thickness tears, 13 partial-thickness tears, and 15 intact cuffs. In all, 35 (88%) full-thickness tears were correctly diagnosed on conventional MRI and 40 (100%) on high-resolution MRI. MR arthrography delineated 11 of 12 (92%) full-thickness tears. Altogether, 5 (38%) of the partial-thickness tears were detected on conventional MRI, and 12 (92%) were clearly demonstrated on high-resolution MRI. MRI arthrography depicted three (60%) of five partial-thickness tears. High-resolution MRI showed higher sensitivity than conventional MRI (P < 0.05) and had values equivalent to those of MRI arthrography for diagnosing partial-thickness tears. CONCLUSION: High-resolution MRI with a microscopy coil is a feasible, noninvasive technique for diagnosing rotator cuff tears.

The fatal risk in hepatic artery embolization for hemostasis after pancreatic and hepatic surgery: importance of collateral arterial pathways.

PURPOSE: To assess retrospectively the cause of hepatic failure related to hepatic arterial embolization (HAE) for hemostasis after pancreaticoduodenectomy or hepatic lobectomy. MATERIALS AND METHODS: Between June 1993 and March 2006, Twenty HAEs in 17 patients (15 men, two women; mean age, 64 years) were performed. Angiographic findings, including portal vein stenosis, collateral arterial pathways after HAE, and the difference of embolic materials, were recorded. The morbidity (hepatic failure and abscess) and mortality were detailed according to collateral arterial pathways, portal vein stenosis, and embolic material used. RESULTS: Bleeding was controlled in all patients, although two patients required repeat embolization. Hepatic failure (n = 8) and abscess (n = 2) arose in nine of 20 HAEs. Death occurred after six of eight HAEs complicated by hepatic failure. The morbidity and mortality rates of HAE were 45% and 30%, respectively. Hepatic complication was eight times more likely to occur (P = .005) in cases with no hepatic collaterals involving hepatic, replaced, or accessory hepatic arteries. Death was observed only in the cases without hepatic collaterals (P = .011). The correlation between the embolization outcome and the presence of portal vein stenosis or the difference of embolic materials was not significant (P > .61). CONCLUSIONS: HAE can be used to successfully control bleeding secondary to hepatic arterial rupture. In the absence of hepatic collaterals, collateral circulation distal to the occlusion from nonhepatic sources may be inadequate and lead to hepatic failure after HAE.

Bronchial artery anatomy: preoperative 3D simulation with multidetector CT.

PURPOSE: To preoperatively evaluate anatomic variations of the bronchial arteries by obtaining three-dimensional (3D) simulations with multidetector computed tomography (CT). MATERIALS AND METHODS: This study was approved by the institutional review board, and written informed consent was obtained from all participants. Seventy-three consecutive patients with esophageal cancer underwent dynamic multidetector CT. The data were used to generate 3D simulations of the thoracic cavity. These images were then used to evaluate anatomic variations of the bilateral bronchial arteries and the mediastinal course in relation to the esophagus and trachea-bronchi. The preoperative CT findings were correlated with the thoracoscopic findings. RESULTS: CT depicted 118 right bronchial and 105 left bronchial arteries. The right bronchial arteries arose from the intercostal-bronchial trunk (IBT), thoracic aorta, common trunk of both bronchial arteries (CTB), and right subclavian artery in 61, 15, 38, and four cases, respectively, whereas the left bronchial arteries arose from the thoracic aorta, IBT, and CTB in 63, four, and 38 cases, respectively. The right bronchial arteries followed preferential courses through the mediastinum, depending on the parent artery: All 61 right bronchial arteries that arose from the IBT ran along the right side of the esophagus, dorsal to the trachea-main bronchi, whereas the majority of direct-origin and CTB-type right bronchial arteries and all left bronchial arteries ran along the left side of the esophagus. During right thoracoscopy, all bronchial arteries coursing along the right side of the esophagus were identified, whereas those coursing along the left side of the esophagus were frequently out of intraoperative view. Six small right bronchial arteries that were not detected at CT were discovered during surgery. CONCLUSION: Three-dimensional simulation with multidetector CT yields precise preoperative information regarding the anatomy of the bronchial arteries and their variants.

Unilateral moyamoya syndrome involving the ipsilateral anterior and posterior circulation associated with paroxysmal nocturnal hemoglobinuria.

Moyamoya refers to a phenomenon of stenoocclusive changes at or around the terminal part of the internal carotid artery (ICA). Moyamoya vessels develop in patients with (moyamoya syndrome) or without (moyamoya disease) various underlying diseases or conditions. Recent evidence shows that stenoocclusive lesions tend to involve the ipsilateral ICA system and posterior cerebral artery (PCA) predominantly in moyamoya disease. A 53-year-old Japanese woman with paroxysmal nocturnal hemoglobinuria presented with cerebral infarction from stenoocclusive involvement in the ipsilateral ICA and PCA associated with moyamoya vessels; she had no contralateral vascular lesion. Although predominant involvement of the ipsilateral ICA and PCA was associated with underlying disease (moyamoya syndrome) in the present case, it is a characteristic finding of moyamoya disease. We discuss the possible pathogenesis of the vascular changes of this case.

Hippocampal activation associated with successful external source monitoring.

Studies demonstrating hippocampal activation associated with memories for persons from whom information is acquired (external source monitoring) are lacking. In this study, we used functional magnetic resonance imaging (fMRI) to investigate whether the medial temporal lobe (MTL), especially the hippocampus, is activated during the retrieval of external source information as well as during the retrieval of the items themselves. Before the fMRI, subjects intentionally studied photographs with names that were presented by either a woman or a man in a videotape. During the fMRI, subjects were asked to judge whether each photograph was new or old and, if they judged it as old, to indicate which person had presented the photograph during the study phase according to a confidence rating (high or low). The results showed that successful retrieval of a source with high confidence was associated with increased activity in the hippocampus and that correct item recognition with failed source retrieval and low confidence for a source (i.e., item-only hits) was associated with decreased activity in the perirhinal cortex. Further analysis revealed that the hippocampus was also associated with familiarity/novelty distinction for the items themselves. The present study is the first to provide evidence that hippocampal activation is associated with external source monitoring. The results also support existing models suggesting that the hippocampus is associated with recollection-based recognition and the perirhinal cortex with familiarity-based recognition, with the possibility that the hippocampus plays roles in both recognition processes.

Imaging of hypoxic lesions in patients with gliomas by using positron emission tomography with 1-(2-[18F] fluoro-1-[hydroxymethyl]ethoxy)methyl-2-nitroimidazole, a new 18F-labeled 2-nitroimidazole analog.

OBJECT: Assessment of hypoxic conditions in brain tumors is important for predicting tumor aggressiveness and treatment response. A new hypoxia imaging agent, 1-(2-[(18)F]fluoro-1-[hydroxymethyl]ethoxy)methyl-2-nitroimidazole (FRP-170), with higher image contrast and faster clearance than preexisting hypoxia tracers for PET, was used to visualize hypoxic tissues in 8 patients with glioma. METHODS: The FRP-170 was injected and PET imaging was performed 2 hours later in 8 patients, including 3 with glioblastoma multiforme, 2 with oligodendroglioma, and 1 each with diffuse astrocytoma, anaplastic ganglioglioma, and recurrent anaplastic astrocytoma. All 8 patients also underwent MR imaging, and some patients underwent [(11)C]methionine or [(18)F]fluorodeoxyglucose PET, and proton MR spectroscopy for comparison. Tissues obtained at biopsy or radical resection were immunostained with hypoxia-inducible factor-1alpha (HIF-1alpha) antibody for the confirmation of hypoxia, except in the patient with recurrent anaplastic astrocytoma who was treated using Gamma Knife surgery. RESULTS: The FRP-170 PET images showed marked uptake with upregulation of HIF-1alpha in the 3 glioblastomas multiforme, and moderate uptake in the recurrent anaplastic astrocytoma and one oligodendroglioma, but no uptake in the other tumors. The FRP-170 PET images showed positive correlation with HIF-1alpha immunoreactivity and some correlation with FDG PET and MR imaging enhancement, but no correlation with [(11)C]methionine PET. Imaging with FRP-170 PET seemed to be more sensitive for detecting hypoxia than identifying the lactate peak on proton MR spectroscopy. CONCLUSIONS: Imaging with FRP-170 PET can visualize hypoxic lesions in patients with glioma, as confirmed by histological examination. This new method can assess tumor hypoxia preoperatively and noninvasively.

Clinical utility of diffusion tensor imaging for evaluating patients with diffuse axonal injury and cognitive disorders in the chronic stage.

Although diffuse axonal injury (DAI) usually ellicits cognitive disorders, abnormal brain findings are generally undetected by conventional imaging techniques. The aim of this study was to evaluate the feasibility of using diffusion tensor imaging (DTI) to detect lesions in DAI patients and to investigate the correlation between DAI lesions and cognitive disorders. We examined 16 healthy controls and 11 patients with DAI. Using voxel-based analysis, we found that there were significantly more brain regions with decreased fractional anisotropy (FA) in the brain but DAI patients compared to healthy controls (p < 0.001), whereas few lesions were detected via conventional magnetic resonance imaging. There was a significant relationship between the results of the Wechsler Adult Intelligence Scale-Revised, Trail Making Test, and some indices of the Wechsler Memory Scale-Revised and the decreased FA observed in various areas of the brain (p < 0.001). The total cognitive scores on the functional independence and functional assessment measures, which represent behavioral problems, were correlated with the cluster (number of DAI lesions, p = 0.007) and voxel numbers (total size of all DAI lesions, p = 0.001). In the fiber tractography-based analysis, DAI patients with memory disorders showed an interruption of fibers within the fornix compared to healthy controls. These results indicate that DTI is a useful technique not only for detecting DAI lesions but also for examining cognitive disorders in DAI patients.

Treatment of in-stent restenosis with beraprost sodium: an experimental study of short- and intermediate-term effects in dogs.

1. The aim of the present study was to evaluate the inhibitory effects of the short-term administration of beraprost sodium, a stable prostaglandin I(2) analogue, on neointimal thickening after stenting. 2. To examine the immediate and short-term effects, Z-stents were placed in the iliac veins of 12 dogs, which were randomly assigned to either a beraprost-treated or control (saline) group. Beraprost (0.35 microg/kg per min) or saline (1.5 mL/min) was administered 30 min before stenting and was continued for 5 h thereafter. Platelet aggregation was measured before and after drug administration. At 3, 7 and 14 days after stenting, dogs were killed and immunohistochemical staining for proliferating cell nuclear antigen was used to quantify the proliferation of vascular smooth muscle cells (SMC). To evaluate intermediate-term effects, a Z-stent was placed in the right iliac vein in 10 dogs, followed by beraprost treatment. Three days later, a second Z-stent was placed contralaterally with saline infusion as a control. After 4 weeks, dogs were killed and neointimal thickness was measured under a light microscope to calculate the intima : media area ratio. 3. Platelet aggregation was more significantly suppressed in the beraprost-treated than in the control group (P = 0.01). In addition, SMC proliferation was significantly lower in the beraprost-treated group 7 and 14 days after stenting (P < 0.05). Over the intermediate term, the intima : media area ratio was significantly lower in the beraprost-treated vein compared with control (P < 0.05). 4. In conclusion, short-term beraprost treatment during stenting suppresses in situ platelet aggregation and SMC proliferation, thus reducing neointimal thickening.

Minimum apparent diffusion coefficient is significantly correlated with cellularity in medulloblastomas.

OBJECTIVE: On diffusion-weighted magnetic resonance (MR) images, posterior fossa tumors may exhibit the various signal intensity and apparent diffusion coefficient (ADC) reflecting their histology and cellularity. The purpose of this study was to evaluate the relationship between ADC and tumor cellularity in medulloblastoma and other posterior fossa tumors. METHODS: Pre-operative diffusion-weighted MR images were retrospectively reviewed in 26 patients with posterior fossa neoplasms: 11 medulloblastomas, one atypical teratoid/rhabdoid tumor (AT/RT), four glioblastomas, four ependymomas, three pilocytic astrocytomas and three hemangioblastomas. The minimum ADC (minADC) value of each tumor was determined on ADC maps derived from isotropic diffusion-weighted MR images. The minADC values were compared by a two-tailed t-test. Tumor cellularity measured in surgical specimens was compared with the minADC value by simple linear regression analysis. RESULTS: The mean minADC value of the medulloblastoma was significantly lower than those of ependymoma, pilocytic astrocytoma and hemangioblastoma without overlap in the range of minADC values. Therefore, medulloblastomas could be clearly differentiated by absolute minADC values. AT/RT and glioblastoma had similar minADC values to medulloblastoma. Tumor cellularity was negatively correlated with the minADC value in medulloblastomas and other posterior fossa tumors. DISCUSSION: The low minADC value of medulloblastomas reflects the high tumor cellularity. Analysis of ADC values has high predictive value for the differentiation of medulloblastoma from other posterior fossa tumors.

Minimum apparent diffusion coefficient for the differential diagnosis of ganglioglioma.

OBJECTIVES: The utility of apparent diffusion coefficient (ADC) values was evaluated for the differential diagnosis of ganglioglioma. METHODS: Ten consecutive patients, five men and five women, aged from 14 to 67 years, with histologically proven supratentorial gangliogliomas, underwent diffusion-weighted magnetic resonance imaging with echo planar imaging technique. The minimum ADC (minADC) of each tumor was pre-operatively determined from several regions of interest. The minADC of ganglioglioma was compared with that of low- or high-grade astrocytomas (astrocytoma, anaplastic astrocytoma and glioblastoma). Tumor cellularity of gangliogliomas was compared with the minADC. RESULTS: The mean minADC of the gangliogliomas (1.45 +/- 0.20 x 10(-3) mm(2)/s) was significantly higher than that of the low- or high-grade astrocytomas. Tumor cellularity of ganglioglioma was inversely correlated with the minADC value. DISCUSSION: The minADC value reflects in the low tumor cellularity of gangliogliomas and may provide a method for the differential diagnosis of ganglioglioma.

Correct diagnosis of vascular encasement and longitudinal extension of hilar cholangiocarcinoma by four-channel multidetector-row computed tomography.

Accurate diagnosis of local invasion of hilar cholangiocarcinomas is challenging due to their small size and the anatomic complexity of the hepatic hilar region. On the other hand, the correct diagnosis of local invasion is essential for assuring the possibility of curative surgery. The purpose of this study was to evaluate the feasibility of four-channel multidetector-row computed tomography (MDCT) in the assessment of vascular and bile duct involvement, by which we could obtain useful information for the surgical management of hilar cholangiocarcinoma. The subjects were 18 patients for whom the extent of tumor invasion was surgically and pathologically confirmed. All patients underwent preoperative multiphasic CT scanning by MDCT. Arterial and portal dominant phases were acquired using a detector configuration of 1.25 mm X 4 mm, and both axial and multiplanar reconstructed images were interpreted. Longitudinal extension was evaluated up to second-order branches. Vascular invasion is considered to be the degree of tumor contiguity to the hepatic arteries and portal vein and was graded by CT. The longitudinal extension was correctly diagnosed in 14 patients (77.8%). Hepatic artery invasion was correctly diagnosed in 17 patients with sensitivity of 100% and specificity of 90%, respectively. Portal vein invasion was correctly diagnosed in 47 of 51 branches with sensitivity and specificity of 92.3% and 90.2%, respectively. Multiplanar reconstructed images contributed to the correct diagnosis for both vascular encasement and longitudinal tumor extension. In conclusion, MDCT is useful in preoperative evaluation of hilar cholangiocarcinoma, especially when combined with multiplanar reconstructed images.

Utility of subtraction ictal SPECT images in detecting focal leading activity and understanding the pathophysiology of spasms in patients with West syndrome.

PURPOSES: The aims of the study were to evaluate the detectability of focal leading activity in three cases of West syndrome having focal abnormal activity on EEG by comparing subtraction ictal images and raw ictal images, and to interpret the results in 16 cases. METHODS: Subtraction images were constructed using iNeurostat (revision 2). RESULTS: In three cases with focal abnormal activity on EEG, subtraction ictal images reflected the EEG findings; in contrast, raw ictal images did not. Diverse degrees of cortical hyperperfusion, ranging from zero to 10 sites, seen in the other 13 cases seemed to reflect spasm pathophysiology and rapid spasm propagation. Subtraction ictal images also allowed the ready detection of hyperperfusion of subcortical structures and of a tight cortico-subcortical relationship in a subset of cases. CONCLUSIONS: We showed the superiority of subtraction ictal images in detecting the focal epileptic region and in showing propagation pathways from the cortex to subcortical structures. A subset of spasms in WS may be focal cortical-onset secondarily generalized seizures. We believe that subtraction analysis is valuable in patients with complex WS who have partial seizures and spasms simultaneously along with focal epileptic EEG activity, as they will likely be candidates for epilepsy surgery.

Differentiation of pathologic subtypes of papillary renal cell carcinoma on CT.

OBJECTIVE: We reviewed the CT findings of the subtypes of papillary renal cell carcinoma (RCC), which behave differently clinicopathologically. CONCLUSION: The CT features of the two pathologic subtypes of papillary RCC differ, probably reflecting their different pathologic features. Type 1 tumors have more distinct margins than type 2 tumors and have homogeneous density. Although type 2 tumors in the early stages show findings similar to those of type 1 tumors, they are at more advanced stages on the whole, with CT features showing indistinct margins, frequent centripetal infiltration, and tumor thrombi in all pT3b cases. Radiologists should be familiar with the CT features of papillary RCC that suggest different pathologic behaviors, such as tumor stage, tumor proliferation, and microvascular or vascular invasion.

Discriminating between silent cerebral infarction and deep white matter hyperintensity using combinations of three types of magnetic resonance images: a multicenter observer performance study.

INTRODUCTION: We attempted to determine the most appropriate combination of magnetic resonance (MR) images that can accurately detect and discriminate between asymptomatic infarction and deep white matter hyperintensity (DWMH); these lesions have different clinical implications and are occasionally confused. MATERIALS AND METHODS: We performed an observer performance analysis using cerebral MR images of 45 individuals with or without asymptomatic small white matter infarction and/or mild DWMH who participated in a physical checkup program at four institutions. Six observers interpreted whether infarction and/or DWMH existed in combinations of two or three image types of the T1-weighted images (T1WI), T2-weighted images (T2WI), and fluid-attenuated inversion recovery (FLAIR) images. The observers' performance was evaluated with a receiver operating characteristic (ROC) analysis. RESULTS: The averaged area under the ROC curve (Az) for detecting a infarction was significantly larger in the combination of all the three image types (0.95) than that in any combinations of the two image types (T1WI and FLAIR images, 0.87; T2WI and FLAIR images, 0.85; T1WI and T2WI, 0.86). The Az for detecting DWMH was significantly smaller in the combination of T1WI and T2WI (0.79) than that in other image combinations (T1WI and FLAIR, 0.89; T2WI and FLAIR, 0.91; T1WI, T2WI, and FLAIR, 0.90). CONCLUSION: The combination of T1WI, T2WI, and FLAIR images is required to accurately detect both small white matter infarction and mild DWMH.

Validation of the use of calibration factors between the iodine concentration and the computed tomography number measured outside the objects for estimation of iodine concentration inside the objects: phantom experiment.

PURPOSE: The aim of this study was to validate the use of a calibration factor measured outside the object for estimating the iodine concentration inside the object to improve the accuracy of the quantitative contrast-enhanced computed tomography (CT). MATERIALS AND METHODS: Several known concentrations (0, 6, 9, and 12 mg I/ml) of iodine contrast material (CM) samples were placed inside and outside cylindrical acrylic phantoms of two sizes and were imaged under various combinations of the tube voltages and currents (kV/mAs-80/200, 100/200, 120/200, 140/200) to obtain K factors. The K factors were compared between the phantoms and among the tube voltages. Each CM concentration was estimated from the CT number using the K factor measured outside the phantom. RESULTS: The K factors varied between the phantoms or among the tube voltages (P < 0.05). Although there were statistically significant variations in K factors among the different regions in a phantom, the mean variation coefficient was 3%-4%. The mean error of the estimated concentration was -5.5%. CONCLUSION: The CM concentration should be accurately estimated at the region within a patient's body using the K factor measured at the surface of the body regardless of body size and tube voltage.

High-resolution monochrome liquid crystal display versus efficient household colour liquid crystal display: comparison of their diagnostic performance with unenhanced CT images in focal liver lesions.

This study compared the ability of an efficient household liquid crystal display (LCD) and a medical high-resolution LCD to detect small hepatic lesions on unenhanced computed tomography (CT) images. We obtained the images from 100 subjects who had undergone abdominal CT. They consisted of 41 patients with a single space-occupying lesion (SOL) in the liver and 59 control subjects with no SOL. Independently, five radiologists rated their confidence concerning the presence of hepatic SOLs on a continuous scale from 0 to 1. Receiver-operating characteristic (ROC) analysis was performed using the jackknife method using the program LABMRMC. We evaluated the differences in A(z) based on the 95% confidence intervals. The mean A(z) of the five observers was 0.9594 with the efficient household LCD vs. 0.9335 with the medical high-resolution LCD. The difference was -0.0422, and the 95% confidence interval was -0.1101 to 0.0257 (p=0.2203). There was no significant difference in the A(z) value between the two types of LCDs. The diagnostic performance with the household LCD was comparable to that with the high-resolution LCD, implying that the former type of LCD can be used to diagnose CT images.