The Role of Core Needle Biopsy and Its Impact on Surgical Management in Patients with Medullary Thyroid Cancer: Clinical Experience at 3 Medical Institutions.

BACKGROUND AND PURPOSE: Medullary thyroid carcinoma is an uncommon malignancy that is challenging to diagnose. Our aim was to present our experience using core needle biopsy for the diagnosis of medullary thyroid carcinoma compared with fine-needle aspiration. MATERIALS AND METHODS: Between January 2000 and March 2012, 202 thyroid nodules in 191 patients were diagnosed as medullary thyroid cancer by using sonography-guided fine-needle aspiration, core needle biopsy, or surgery. One hundred eighty-three thyroid nodules in 172 patients were included on the basis of the final diagnosis. We evaluated the sensitivity and positive predictive value of fine-needle aspiration and core needle biopsy for the diagnosis of medullary thyroid cancer. We compared the rate of a delayed diagnosis, a diagnostic surgery, and surgery with an incorrect diagnosis for fine-needle aspiration and core needle biopsy and investigated the factors related to the fine-needle aspiration misdiagnosis of medullary thyroid cancer. RESULTS: Fine-needle aspiration showed 43.8% sensitivity and 85.1% positive predictive value for the diagnosis of medullary thyroid cancer; 25.7% (44/171) of patients had a delayed diagnosis, while 18.7% (32/171) underwent an operation for accurate diagnosis, and 20.5% (35/171) underwent an operation with an incorrect diagnosis. Core needle biopsy achieved 100% sensitivity and positive predictive value without a delay in diagnosis (0/22), the need for a diagnostic operation (0/22), or an operation for an incorrect diagnosis (0/22). A calcitonin level of <100 pg/mL was the only significant factor for predicting the fine-needle aspiration misdiagnosis of medullary thyroid cancer (P = .034). CONCLUSIONS: Core needle biopsy showed a superior sensitivity and positive predictive value to fine-needle aspiration and could optimize the surgical management in patients with medullary thyroid cancer. Because the ability of fine-needle aspiration to diagnose medullary thyroid cancer significantly decreases in patients with serum calcitonin levels of <100 pg/mL, core needle biopsy could be indicated for these patients to optimize their surgical management.

Correlation between CT and diffusion-weighted imaging of acute cerebral ischemia in a rat model.

BACKGROUND AND PURPOSE: The quantitative temporal relationship between changes in CT attenuation, ADC value, and DWI signal intensity of acute ischemic tissue has not yet been determined in an animal model. This study was performed to determine the temporal relationship between CT attenuation, ADC value, and DWI signal intensity in acute cerebral ischemia. MATERIALS AND METHODS: CT and DWI were performed at 1, 3, 5, 7, and 9 hours after left MCA occlusion in 11 rats. Mean values for CT attenuation, ADC, and DWI signal intensity were determined for the ischemic hemisphere and contralateral normal hemisphere. Temporal changes in each mean value and the relationship between CT attenuation and ADC value and DWI signal intensity were evaluated. RESULTS: The decrease of CT attenuation and the increase of DWI signal intensity occurred gradually after MCA occlusion, while ADC value decreased rapidly at 1 hour. Although correlation was significant between time and rCT or rDWI (P<.01, respectively), no correlation between time and rADC was found (P=.33). There was a significant linear correlation between rCT and rDWI (r=0.497, P<.01), but no significant correlation between rCT and rADC (P=.509) was found. CONCLUSIONS: The temporal change in CT attenuation was different from that in ADC value with no significant linear correlation between CT attenuation and ADC value for acute cerebral ischemia. However, rCT and rDWI showed a modest correlation.

Nonenhancing intramedullary astrocytomas and other MR imaging features: a retrospective study and systematic review.

BACKGROUND AND PURPOSE: Most intramedullary astrocytomas have been known to exhibit at least some enhancement on MR imaging regardless of cell type or tumor grade. The purpose of this study was to evaluate the incidence of nonenhancing intramedullary astrocytomas through a retrospective study within our institutions and a systematic review of the medical literature. MATERIALS AND METHODS: A total of 19 consecutive patients (male to female ratio, 11:8; mean age, 27.84 +/- 19.0 years) with primary intramedullary astrocytomas (3 WHO grade I, 13 WHO grade II, 3 WHO grade III) who underwent preoperative MR imaging with contrast enhancement were included in this retrospective study from 4 institutions. The tumor-enhancement patterns were classified into the following categories: 1) no enhancement, 2) focal nodular enhancement, 3) patchy enhancement, 4) inhomogeneous diffuse enhancement, and 5) homogeneous diffuse enhancement. Seven articles including MR imaging enhancement studies of intramedullary astrocytomas were eligible for literature review. RESULTS: In the retrospective study, 6 astrocytomas (32%), including 2 anaplastic astrocytomas, did not enhance at all. Focal nodular enhancement was identified in 5 astrocytomas (26%); patchy enhancement, in 3 (16%); inhomogeneous diffuse enhancement, in 5 (26%); and homogeneous diffuse enhancement, in none. In the literature review, the frequency of nonenhancing intramedullary astrocytomas was 14 of 76 (18%), including 2 anaplastic astrocytomas. CONCLUSIONS: Nonenhancing intramedullary astrocytomas are not uncommon and comprise between 20% and 30% of intramedullary astrocytomas. Therefore, astrocytoma must remain in the differential diagnosis of nonenhancing intramedullary lesions, particularly if the lesion demonstrates a prominent mass effect or cord expansion.

Imaging features of meningeal inflammatory myofibroblastic tumor.

BACKGROUND AND PURPOSE: Meningeal inflammatory myofibroblastic tumor (IMT) has been rarely reported, and its prognosis is still unclear. Our purpose was to describe the imaging features of patients with meningeal IMT and their results on follow-up studies. MATERIALS AND METHODS: Twenty-four MR images in 10 consecutive patients with pathologically proved meningeal IMTs were retrospectively evaluated, focusing on the lesion distribution, signal intensity (SI), and contrast-enhancement pattern with a review of the clinical records. RESULTS: Eight patients with intracranial IMT showed localized (n = 4) or diffuse (n = 4) dural thickening, a single mass (n = 5) or 2 (n = 2) dural-based masses with surrounding edema, dural venous sinus thrombosis (n = 5), and leptomeningeal involvement (n = 5). Extracranial involvement of the mastoid (n = 2) and orbit (n = 2) was also associated. Each of the 2 patients with intraspinal IMT showed a dural-based mass and a segmental dural thickening, respectively. All of the thickened dura showed low SI on T2-weighted images, iso-SI on T1-weighted images, and diffuse contrast enhancement. Variable recurrences with dural-based masses, mastoid involvement, or nasolacrimal duct involvement were observed in all 4 patients with diffuse intracranial IMT, but not in the others. CONCLUSIONS: Localized or diffuse dural thickening of T2 low SI and diffuse contrast enhancement combined with dural-based masses are a common MR imaging finding of meningeal intracranial IMT. Adjacent leptomeningeal involvement and dural venous sinus thrombosis are frequently associated. The diffuse type has a tendency toward recurrence.

High b-value diffusion (b = 3000 s/mm2) MR imaging in cerebral gliomas at 3T: visual and quantitative comparisons with b = 1000 s/mm2.

BACKGROUND AND PURPOSE: High b-value diffusion-weighted imaging (DWI) provides different features not appreciated at lower b-value and have been recently studied in several clinical issues. The purpose of this study was to assess whether DWI at b = 3000 s/mm(2) is more useful in discriminating high-grade and low-grade gliomas than DWI at b = 1000 s/mm(2) at 3T. MATERIALS AND METHODS: DWIs at both b = 1000 and 3000 s/mm(2) were performed at 3T in 62 patients, 49 high-grade gliomas (20 World Health Organization [WHO] grade III and 29 grade IV) and 13 low-grade gliomas (13 grade II). Visual assessments based on 5-point scaled evaluations, receiver operating characteristic (ROC) curve analysis, and quantitative assessment based on DWI signal intensity (SI) ratio (tumor SI/normal SI) and apparent diffusion coefficient (ADC) values were compared between DWIs at b = 1000 and 3000 s/mm(2). RESULTS: By visual assessment, DWI at b = 3000 s/mm(2) showed more conspicuous hyperintensity in high-grade gliomas and hypointensity in low-grade gliomas than DWI at b = 1000 s/mm(2). Sensitivity and specificity at b = 3000 s/mm(2) were higher than at b = 1000 s/mm(2) (83.7%, 84.6% vs 69.4%, 76.9%, respectively). Quantitative assessments showed that mean SI ratio of high-grade gliomas was significantly higher than that of low-grade gliomas at both b-values. The mean ADC value of high-grade gliomas was significantly lower than that of low-grade gliomas at both b-values. The difference between the SI ratios of high-grade and low-grade gliomas was significantly larger at b = 3000 s/mm(2) than at b = 1000 s/mm(2). CONCLUSION: DWI at b = 3000 s/mm(2) is more useful than DWI at b = 1000 s/mm(2) in terms of discriminating high-grade and low-grade gliomas at 3T.

A T1 hyperintense perilesional signal aids in the differentiation of a cavernous angioma from other hemorrhagic masses.

BACKGROUND AND PURPOSE: A cavernous angioma is a developmental vascular malformation with a high risk of hemorrhage. The purpose of this work was to retrospectively determine whether an MR sign of T1 hyperintense perilesional signal intensity is useful for the differentiation of cavernous angioma from other hemorrhagic cerebral masses. MATERIALS AND METHODS: The institutional review board approved this study. We retrospectively evaluated the MR images of 72 patients with acute or subacute cerebral hemorrhagic lesions with perilesional edema (29 cavernous angiomas, 13 glioblastomas, 1 oligodendroglioma, 16 metastatic tumors, and 13 intracerebral hemorrhages) for the presence of T1 hyperintense perilesional signal intensity. In addition, T1 signal intensities of a perilesional edema were quantitatively analyzed. In cavernous angiomas, volumes of hemorrhagic lesions and perilesional edemas, lesion locations, presence of contrast enhancement, and time intervals between symptom onset and MR imaging were also assessed. Data were analyzed using unpaired t test or Fisher exact test. RESULTS: T1 hyperintense perilesional signal intensity sign was found in 18 (62.1%) of 29 cavernous angiomas, in 1 (6.3%) of 16 metastases, and in 0 primary brain tumors or intracerebral hemorrhages. Sensitivity, specificity, and positive predictive value of this sign for cavernous angioma were 62%, 98%, and 95%, respectively. The perilesional T1 hyperintensity was significantly higher in cavernous angiomas (P = .045) than in normal white matter. Perilesional edema volumes were larger in cavernous angiomas with the MR sign than in cavernous angiomas without the sign (P = .009). CONCLUSION: When the MR sign of T1 hyperintense perilesional signal intensity is present, there is a high probability of cavernous angioma being present in the brain, and this MR sign may be helpful for differentiating cavernous angioma from hemorrhagic tumors and intracerebral hemorrhages.

MR imaging of metronidazole-induced encephalopathy: lesion distribution and diffusion-weighted imaging findings.

BACKGROUND AND PURPOSE: MR imaging features of metronidazole-induced encephalopathy (MIE) have not been fully established. This study was undertaken to determine the topographic distributions and diffusion-weighted imaging (DWI) findings of MIE. MATERIALS AND METHODS: We retrospectively evaluated the initial MR images (n = 7), including DWI (n = 5), and follow-up MR images (n = 4) after drug discontinuation in 7 patents with clinically diagnosed MIE. The topographic distributions of lesions were evaluated on MR images, and DWI signal intensities and apparent diffusion coefficient (ADC) values of the lesions were assessed. RESULTS: MR images demonstrated bilateral symmetric T2 hyperintense lesions in the cerebellar dentate nucleus (n = 7), midbrain (n = 7), dorsal pons (n = 6), medulla (n = 4), corpus callosum (n = 4), and cerebral white matter (n = 1). Brain stem lesions involved the following: tectum (n = 5), tegmentum (n = 4), red nucleus (n = 3) of the midbrain, vestibular nucleus (n = 6), and a focal tegmental lesion involving the superior olivary nucleus (n = 6) and abducens nucleus (n = 4) of the pons and vestibular nucleus (n = 4) and inferior olivary nucleus (n = 1) of the medulla. DWI (n = 5) showed isointensity or hyperintensity of lesions, and the decreased ADC value was found only in the corpus callosum lesions (n = 2). All detected lesions were completely reversible at follow-up except for the single corpus callosum lesion with an initial low ADC value. CONCLUSION: Brain lesions were typically located at the cerebellar dentate nucleus, midbrain, dorsal pons, medulla, and splenium of the corpus callosum. According to DWI, most of the lesions in MIE probably corresponded to areas of vasogenic edema, whereas only some of them, located in the corpus callosum, corresponded to cytotoxic edema.

Pituitary adenoma, craniopharyngioma, and Rathke cleft cyst involving both intrasellar and suprasellar regions: differentiation using MRI.

AIMS: To determine the differential magnetic resonance imaging (MRI) features of pituitary adenoma, craniopharyngioma, and Rathke cleft cyst involving both intrasellar and suprasellar regions. MATERIALS AND METHODS: The MRI images of 64 patients with pituitary adenoma (n=38), craniopharyngioma (n=13), or Rathke cleft cyst (n=13) were retrospectively reviewed by three neuroradiologists. The following characteristics were evaluated: shape, volume, extent, component characteristics, signal intensities of solid portions on T2-weighted images, signal intensities of cystic portions on T1-weighted images, and enhancement patterns of solid portions and cyst walls of tumours. Fisher's exact test applied with Bonferroni correction was used for multiple comparison. A flowchart for differential diagnosis was constructed based on statistical analysis of the results. RESULTS: A snowman shape, solid characteristics, and homogeneous enhancement of the solid portion were more common in pituitary adenomas (p<0.017). A superiorly lobulated shape, third ventricle compression by superior tumour extension, mixed solid and cystic characteristics, and reticular enhancement of the solid portion were more common in craniopharyngiomas (p<0.017). Finally, an ovoid shape, a small tumour volume, cystic characteristics, and no or thin cyst wall enhancement were more common in Rathke cleft cysts (p<0.017). The flowchart yielded diagnostic accuracies as follows: 92.1% in pituitary adenoma; 92.3% in craniopharyngioma; 92.3% in Rathke cleft cyst; and 92.2% overall. CONCLUSION: A combination of MRI findings is helpful in the differential diagnosis of the three tumours involving both intrasellar and suprasellar regions.

Reversed discrepancy between CT and diffusion-weighted MR imaging in acute ischemic stroke.

PURPOSE: We sought to determine whether an early CT ischemic lesion showing parenchymal hypoattenuation might be undetectable on diffusion-weighted imaging (DWI) in acute cerebral ischemia. MATERIALS AND METHODS: We retrospectively evaluated CT and MR images of 70 consecutive patients with acute middle cerebral artery (MCA) infarction. All patients underwent CT and MR imaging within 6 hours of symptom onset. We determined the presence of reversed discrepancy (RD), defined as an early ischemic lesion showing parenchymal hypoattenuation on CT but no hyperintensity on DWI. CT Hounsfield units (HU), apparent diffusion coefficients (ADCs), and perfusion parameters were calculated for RD lesions. RESULTS: RD was found in 9 (12.9%) patients and at basal ganglia (89%). The mean HU of RD lesion was lower than that of normal tissue (DeltaHU, 2.33 +/- 0.74, P < .001). RD lesions showed no significant decrease of ADC (ADC ratio, 0.97 +/- 0.07, P = .059) and cerebral blood flow (relative CBF, 0.87 +/- 0.20, P > 0.05). Delayed DWI hyperintensity occurred in 8 (88.8%) RD lesions, and all lesions progressed to infarction. In 6 (66%) of 9 patients with RD, Alberto Stroke Program Early CT scores of ischemic lesions were lower on CT than those on DWI. CONCLUSION: RD was uncommonly found mainly in basal ganglia, and all RD lesions progressed to infarction at follow-up. Early CT ischemic lesion showing parenchymal hypoattenuation may be undetectable on DWI, and DWI may underestimate extent of severe ischemic tissue in patients with acute MCA infarction.

3T 1H-MR spectroscopy in grading of cerebral gliomas: comparison of short and intermediate echo time sequences.

BACKGROUND AND PURPOSE: Echo time (TE) can have a large influence on the spectra in proton MR spectroscopy ((1)H-MR spectroscopy). The purpose of this study was to comparatively assess the diagnostic value of 3T single-voxel (1)H-MR spectroscopy with short or intermediate TEs in grading cerebral gliomas. METHODS: Single voxel (1)H-MR spectroscopy was performed at 3T in 35 patients with cerebral glioma. The spectra were obtained with both short (35 ms) and intermediate TEs (144 ms). Metabolite ratios of choline (Cho)/creatine (Cr), Cho/N-acetylaspartate (NAA), lipid and lactate (LL)/Cr and myo-inositol (mIns)/Cr were calculated and compared between short and intermediate TEs in each grade. After receiver operating characteristic curve analysis, diagnostic accuracy for each TE in differentiating high-grade glioma from low-grade glioma was compared. RESULTS: At short TE, Cho/Cr and Cho/NAA ratios were significantly lower, and LL/Cr and mIns/Cr were significantly higher, compared with those at intermediate TE, regardless of tumor grade. Lactate inversion at intermediate TE was found in only 2 patients. At both TEs, there were significant differences in Cho/Cr and LL/Cr ratios between low- and high-grade gliomas. Diagnostic accuracy was slightly higher at short TE alone or combined with intermediate TE than intermediate TE alone (85.7% versus 82.9%). CONCLUSION: Metabolite ratios were significantly different between short and intermediate TE. Cho/Cr and LL/Cr ratios at either TE were similarly useful in differentiating high-grade gliomas from low-grade gliomas. If only a single spectroscopic sequence can be acquired, short TE seems preferable because of poor lactate inversion at intermediate TE on 3T single-voxel (1)H-MR spectroscopy.

Serial diffusion-weighted MR Imaging in delayed postanoxic encephalopathy. A case study.

We report a case of delayed postanoxic encephalopathy (DPE) studied with serial diffusion weighted imaging five times in a one-year period along with apparent diffusion coefficient (ADC) map as well as ADC values of periventricular white matter. Compared to the normal value, the ADC values of the white matter were initially low on the three (0.68 +/- 0.08 x 10(-3) mm(2)/s) and seven-week images (0.67 +/- 0.08 x 10(-3) mm(2)/s) but gradually recovered to the normal range on the four, six, and twelve-month images (0.78 +/- 0.05, 0.80 +/- 0.05 and 0.87 +/- 0.11 x 10(-3) mm(2)/s, respectively). Among the several pathogenetic mechanisms associated with DPE, these serial changes may be consistent with cytotoxic edema, from apoptosis, triggered by hypoxia.

Functional magnetic resonance imaging during pantomiming tool-use gestures.

The purpose of this study was to identify the functional fields activated in relation to gestural movements. Using functional magnetic resonance imaging (fMRI), we mapped brain activity in ten right-handed, normal volunteers during activation and control tasks. The activation condition consisted of pantomiming tool-use gestures with either the left hand or right hand, whereas the control condition comprised repetitive, oppositional movements between thumb and index finger. Activated cortical regions were highly lateralized to the left hemisphere during pantomiming of tool use regardless of hand used. Praxis with either hand commonly activated the superior parietal lobule, supplementary motor area, premotor area of the left hemisphere, and cerebellar vermis. However, minimal activation occurred in the inferior parietal lobule, which has been known to be a critical area for praxis generation. Compared with left-hand praxis, right-hand praxis exhibited additional activation in the left putamen and posterior part of the left inferior temporal region. Our findings concur with neuropsychological observations that the left hemisphere in right-handers mediates programming and executing skilled movements and that, within the left hemisphere, praxis is predominantly subserved by the parietal lobe, supplementary motor area, and premotor area. However, unlike previous lesion studies, the results of our fMRI study suggested that the superior parietal lobule more likely than the inferior parietal lobule play an important role in gesture production.

Investigation of juxtasellar and cerebellopontine angle meningiomas and neurogenic tumours: two-phase helical CT.

We performed two-phase helical CT in 31 patients with juxtasellar region and cerebellopontine angle tumours to evaluate its usefulness in differentiating meningiomas from neurogenic tumours. After the intravenous injection of 90 ml contrast medium at 3 ml/s, axial helical images were obtained with delays of 30 and 120 s. After the delayed axial images, we acquired coronal images. Changes in attenuation were assessed visually and quantitatively (by comparing the attenuation in Hounsfield units). There were 17 meningiomas and 14 neurogenic tumours, all pathologically proven. Two-phase helical CT showed a decrease in attenuation in 15 (88%) meningiomas and an increase in 14 (100%) neurogenic tumours from early to delayed axial images. Coronal images showed a decrease in attenuation in all 17 meningiomas and an increase in 13 (93%) of the neurogenic tumours. The mean HU and their ratios were significantly different between meningiomas and neurogenic tumours.

Diffusion-weighted MR imaging of intracerebral hemorrhage.

OBJECTIVE: To document the signal characteristics of intracerebral hemorrhage (ICH) at evolving stages on diffusion-weighted images (DWI) by comparison with conventional MR images. MATERIALS AND METHODS: In our retrospective study, 38 patients with ICH underwent a set of imaging sequences that included DWI, T1-and T2-weighted imaging, and fluid-attenuated inversion recovery (FLAIR). In 33 and 10 patients, respectively, conventional and echo-planar T2* gradient-echo images were also obtained. According to the time interval between symptom onset and initial MRI, five stages were categorized: hyperacute (n=6); acute (n=7); early subacute (n=7); late subacute (n=10); and chronic (n=8). We investigated the signal intensity and apparent diffusion coefficient (ADC) of ICH and compared the signal intensities of hematomas at DWI and on conventional MR images. RESULTS: DWI showed that hematomas were hyperintense at the hyperacute and late subacute stages, and hypointense at the acute, early subacute and chronic stages. Invariably, focal hypointensity was observed within a hyperacute hematoma. At the hyperacute, acute and early subacute stages, hyperintense rims that corresponded with edema surrounding the hematoma were present. The mean ADC ratio was 0.73 at the hyperacute stage, 0.72 at the acute stage, 0.70 at the early subacute stage, 0.72 at the late subacute stage, and 2.56 at the chronic stage. CONCLUSION: DWI showed that the signal intensity of an ICH may be related to both its ADC value and the magnetic susceptibility effect. In patients with acute stroke, an understanding of the characteristic features of ICH seen at DWI can be helpful in both the characterization of intracranial hemorrhagic lesions and the differentiation of hemorrhage from ischemia.

MR imaging of central diabetes insipidus: a pictorial essay.

Central diabetes insipidus (DI) can be the outcome of a number of diseases that affect the hypothalamic-neurohypophyseal axis. The causes of the condition can be classified as traumatic, inflammatory, or neoplastic. Traumatic causes include postoperative sella or transection of the pituitary stalk, while infectious or inflammatory causes include meningitis, lymphocytic hypophysitis, and granulomatous inflammations such as sarcoidosis and Wegener's granulomatosis. Various neoplastic conditions such as germinoma, Langerhans cell histiocytosis, metastasis, leukemic infiltration, lymphoma, teratoma, pituitary adenoma, craniopharyngioma, Rathke cleft cyst, hypothalamic glioma, and meningioma are also causes of central DI. In affected patients, careful analysis of these MR imaging features and correlation with the clinical manifestations can allow a more specific diagnosis, which is essential for treatment.

Triphasic perfusion computed tomography in acute middle cerebral artery stroke: a correlation with angiographic findings.

OBJECTIVE: To evaluate the usefulness of triphasic perfusion computed tomography (TPCT) in diagnosing middle cerebral artery (MCA) occlusion and in assessing the perfusion deficit and collateral circulation in patients with acute ischemic stroke. BACKGROUND: Conventional angiography is the criterion standard for the diagnosis of MCA occlusion and for the assessment of perfusion deficit and collateral blood supply. The risk of hemorrhagic transformation after recanalization of occluded arteries by thrombolytic therapy is considered high when pretherapeutic residual flow is markedly reduced. PATIENTS AND METHODS: In 8 patients within 3 hours of onset of acute MCA stroke, precontrast computed tomographic scans were taken, and then TPCT was performed after power-injector controlled intravenous administration of contrast media. Sequential images of early, middle, and late phases were obtained. The whole procedure took 5 minutes. Perfusion deficit on TPCT was graded as "severe" or "moderate," depending on the state of collateral flow. Digital subtraction angiography (DSA) was performed in all patients within 6 hours of acute stroke. Direct intra-arterial urokinase infusion was begun immediately after the angiographic superselection of the MCA occlusion site in 6 of the 8 patients within 7 hours of onset (range, 4.3-6.2 hours). RESULTS: The DSA findings showed occlusion of the MCA stem (n = 1) and at the bifurcation (n = 4). The sites of proximal MCA occlusion could be identified on the early and middle images of TPCT in all 5 patients. On DSA findings, all 8 patients had a zone of perfusion deficit with markedly slow leptomeningeal collaterals and a zone of perfusion deficit with no collaterals. The zone of severe perfusion deficit on TPCT corresponded to the zone of perfusion deficit with no or few collaterals on angiography, and the zone of moderate perfusion deficit on TPCT corresponded to that of perfusion deficit with markedly slow leptomeningeal collaterals. Early parenchymal hypoattenuation on precontrast computed tomography was confined to the zone of severe perfusion deficit on TPCT. The initial National Institutes of Health Stroke Scale score correlated better with the total extent of severe perfusion deficit and moderate perfusion deficit on TPCT than that of severe perfusion deficit alone. After direct intra-arterial thrombolysis within 7 hours of onset, symptomatic hemorrhagic transformation did not develop in 4 patients with small severe perfusion deficit (33% or less of the presumed MCA territory). However, the remaining 2 patients with large severe perfusion deficit (more than 50% of the presumed MCA territory) deteriorated to death with hemorrhagic transformation. CONCLUSIONS: Triphasic perfusion computed tomography is useful for diagnosing proximal MCA occlusion and assessing perfusion deficit and collateral circulation as reliably as DSA. The zone of severe perfusion deficit on TPCT may be presumed to be the ischemic core, and that of moderate perfusion deficit, the penumbra zone. Triphasic perfusion computed tomography may be used as a rapid and noninvasive tool to make thrombolysis safer.

Usefulness of triphasic perfusion computed tomography for intravenous thrombolysis with tissue-type plasminogen activator in acute ischemic stroke.

BACKGROUND: Intravenous thrombolysis for acute ischemic stroke has been investigated in several clinical trials without enough information on collateral blood flow and perfusion deficit in the ischemic areas. The therapeutic time window varies from patient to patient depending on these factors. Triphasic perfusion computed tomography (TPCT) can provide this information as reliably as conventional angiography. OBJECTIVE: To assess the safety and efficacy of thrombolysis within 3 or 7 hours of stroke onset according to the extent of perfusion deficit on TPCT. METHODS: In 46 patients with acute middle cerebral artery (MCA) territory stroke, TPCT was performed with power injector-controlled, intravenous administration of contrast media after taking precontrast CT scans. Sequential scans of early, middle, and late phases were performed. The entire procedure took 5 minutes. Depending on collateral blood flow, the perfusion deficit on TPCT was graded as "severe perfusion deficit" or "moderate perfusion deficit." Twenty-nine patients were excluded based on clinical, laboratory, and TPCT findings. Seventeen patients were treated with an intravenous recombinant tissue-type plasminogen activator, 0.9 mg/kg. The 17 treated patients were divided into 2 groups: group 1 with small severe perfusion deficit (33% but

Narrow internal auditory canal syndrome: parasaggital reconstruction.

Narrow internal auditory canal (IAC) syndrome is a malformation of the temporal bone, that is defined as an IAC diameter of only 1-2 mm on high-resolution computed tomographic scans (HRCT). This syndrome is known to be caused by the absence (aplasia or hypoplasia) of the vestibulocochlear nerve. We present a case of unilateral narrow IAC syndrome which was diagnosed by HRCT. The aplasia of the vestibulocochlear nerve was confirmed using parasigittal reconstruction magnetic resonance image (MRI). The IAC was composed of two separate canals, one of which contained a facial nerve and the other was empty with aplasia of the vestibulocochlear nerve.

Contralateral EEG slowing and amobarbital distribution in Wada test: an intracarotid SPECT study.

PURPOSE: To relate the occurrence of contralateral electroencephalogram slowing (CES) to amobarbital distribution, we performed electroencephalogram (EEG) monitoring and intracarotid single photon emission computed tomography (SPECT) during an intracarotid amobarbital procedure (IAP). METHODS: IAP was performed on 22 patients with temporal lobe epilepsy. CES was defined as the occurrence of significant EEG slowing on the contralateral hemisphere (>50% of the ipsilateral hemisphere slowing) after amobarbital injection. To map the distribution of the amobarbital, we injected a mixture of amobarbital and (99m)technetium-ethylcysteinate dimer (99mTc-ECD) into the internal carotid artery and performed a brain SPECT 2 h later. In the SPECT images, regions of interest were determined by ipsilateral and contralateral anterior cerebral artery territories (iACA, cACA), ipsilateral and contralateral middle cerebral artery territories (iMCA, cMCA), and ipsilateral and contralateral posterior cerebral artery territories (iPCA, cPCA), as well as ipsilateral and contralateral anterior and posterior mesial temporal regions (iAMT, cAMT, iPMT, cPMT). The perfusion of amobarbital was interpreted visually in each region. RESULTS: Amobarbital was distributed in the iMCA in all the patients; in the iACA in 20 (90.9%) patients; in the iAMT in 14 (63.5%); and in the iPCA and iPMT in only two (9.1%). CES was observed in 13 (59.1%) patients. Cross-perfusion of amobarbital in limited areas of the cACA were observed in only four of 13 patients. Wada retention memory scores (WRMS) showed no significant difference between the CES- (n = 9) and CES+ (n = 13) groups. CONCLUSIONS: Amobarbital rarely perfused the iPCA territory and the iPMT region and was rarely delivered to the contralateral hemisphere. The occurrence of CES was not related to the cross-perfusion of amobarbital. CES appears to be produced by a transient functional disconnection from the ipsilateral hemisphere.

Salivary gland tumors: evaluation with two-phase helical CT.

PURPOSE: To evaluate two-phase helical computed tomography (CT) in the characterization of salivary gland tumors. MATERIALS AND METHODS: Sixty-four patients with major salivary gland tumors underwent two-phase helical CT. The histopathologic diagnosis was obtained by means of surgical resection or biopsy in all patients. After the injection of 90 mL of contrast material at a rate of 3 mL/sec, helical CT scans were obtained at early and delayed phases with scanning delays of 30 and 120 seconds, respectively. The attenuation change and enhancement patterns in the tumors were assessed. The attenuation change in the tumor also was assessed quantitatively as the ratio of the CT number (in Hounsfield units) at delayed phase scanning to that at early phase scanning. RESULTS: There were 35 pleomorphic adenomas, nine Warthin tumors, and 20 malignant tumors. Two-phase helical CT showed increase in attenuation in 30 (86%) pleomorphic adenomas, decrease in eight (89%) Warthin tumors, and increase in 11 (55%) and no change in eight (40%) malignant tumors at delayed phase scanning. A multinodular enhancement pattern was found in only 12 (34%) pleomorphic adenomas. The ratio of CT numbers was significantly different between Warthin tumors and pleomorphic adenomas and between Warthin tumors and malignant tumors. CONCLUSION: The analysis of enhancement patterns by using two-phase helical CT will be helpful in the differential diagnosis of salivary gland tumors.