Characteristics of Internal Carotid Artery Stenosis in Patients with Acute Ischemic Stroke

BACKGROUND: It has been known that Asians are more likely to develop atherosclerosis of the intracranial arteries while Caucasians have more extracranial arterial diseases. Angiographic distribution and frequency of the carotid artery stenosis have not been well known in Korean patients with acute ischemic stroke. METHODS: From the Yonsei Stroke Registry, a total of 300 acute ischemic stroke patients, who were evaluated by a conventional cerebral angiography from July 1997 to September 2000, were enrolled for this study. Patients were divided into three groups: isolated intracranial internal carotid artery (ICA) stenosis (IICA group); isolated extracranial ICA stenosis (EICA group); and combined stenosis of intracranial and extracranial ICAs (combined group). The clinical and angiographical characteristics were investigated and compared among them. RESULTS: A total of 107 patients had stenotic lesions in the ICA. They were 45 patients with lesions in the intracranial ICA (IICA group), 42 in the extracranial ICA (EICA group), and 20 patients in the both intracranial and extracranial ICAs (combined group). No significant differences were found among the three groups in terms of the degree of stenosis (50.2%, 49.6%, 56.8% each: p= 0.34), risk factors of ischemic stroke, and frequency of combined stenosis in the other intracranial arteries. CONCLUSIONS: ICA stenosis was common in patients with acute ischemic stroke. Significant differences of the frequency and risk factors between intracranial and extracranial ICA stenosis were not found. ICA stenosis at the extracranial portion as well as at the intracranial portion should be considered as a common cause of ischemic stroke occurring in the carotid artery system.

Comparison of Orbital Pseudotumor and Lymphoma: Clinical and Radiological Findings

PURPOSE: To compare the clinical and radiological findings of orbital pseudotumor with those of orbital lymphoma. MATERIALS AND METHODS: The clinical and radiological features of 12 orbital pseudotumors were compared with those of 17 orbital lymphomas, the nature of all lesions being confirmed by tissue biopsy. Twenty-four CT scans and nine MR images were retrospectively reviewed and compared, with special focus on the location of a tumor in the orbit, the invasion of periorbital structures, tumor margin, bilaterality, and signal intensity. The initial symptoms at admission were also classified and compared. RESULTS: In 50% of cases, orbital pseudotumors were located in both extraconal and intraconal space; 75% involved two or more extraocular muscles, and 33% involved the optic nerve. Margins were either infiltrative (75%) or ill-defined (92%). As for orbital lymphomas, 64% occupied extraconal space, invading one or less extraocular muscle (76%) and conjunctiva (29%). Seventy-one percent had a sharp margin, and 65% were lobulated or round. In pseudotumors, orbital pain and visual loss were major symptoms, while in lymphomas a painless orbital mass was the initial symptom. CONCLUSION: CT or MR image analysis of lesion location, margin, and the involvement of adjacent extra-ocular muscle or optic nerves may help differentiate between orbital lymphoma and orbital pseudo tumor.

MR Imaging of Trigeminal Neuropathy

Research Institute of Radiological Science, Yonsei University The trigeminal nerve is the largest of the cranial nerves and has both sensory and motor functions. It can be divided into proximal (brainstem, preganglionic, gasserian ganglion, and cavernous sinus) and distal (extracranial opthalmic, maxillary, and mandibular) segments. Patients with trigeminal neuropathy present with a wide variety of symptoms, and lesions producing those symptoms may occur anywhere along the protracted course of the trigeminal nerve, from its distal facial branches to its nuclear columns in the brainstem. The purpose of this article is to illustrate the normal anatomy of the trigeminal nerve and associated various pathologic conditions. These are arranged anatomically according to their site of interaction with it.

MR Imaging Findings of Generalized Tonic Clonic Seizure Induced Brain Changes

PURPOSE: To evaluate MRI signal changes in the brain induced by generalized tonic clonic seizure. MATERIALS AND METHODS: Six patients who underwent MRI within three days of generalized tonic clonic seizure were retrospectively reviewed. Diffusion-weighted images were added in three patients during initial exami-nation, and in six, the follow-up MRI was performed nine days to five months after the onset of seizure. We evaluated the patterns of signal change, location of the lesion and degree of contrast enhancement, and the signal change seen on diffusion weighted images. We also compared the signal changes seen on initial and follow-up MRI. RESULTS: In all six patients, MR images showed focally increased T2 signal intensity, and swelling and increased volume of the involved cortical gyrus. In five, the lesion was mainly located in the cortical gray matter and subcortical white matter; namely, in the bilateral cingulate gyri, and the bilateral parieto-occipital, left parietal, left frontoparietal, and left temporal lobe. In the remaining patient, the lesion was located in the right hippocampus. Two patients showed bilateral lesions and one showed multiple lesions. In four patients, T1- weighted images revealed decreased signal intensity of the same location, and in one, gyral contrast enhancement was noted. On diffusion-weighted images, three patients showed increased signal intensity. Follow-up MRI demonstrated complete resolution of the abnormal signal change (n=5), or a decrease(n=1). CONCLUSION: A transient increase in MR signal intensity with increased volume was noted in cortical and subcortical white matter after generalized tonic clonic seizure. This finding reflects the vasogenic and cytotoxic edema induced by seizure and can help exclude etiologic lesions such as tumors, inflammation and demyelinating disease that induce epilepsy.

Hippocampal and Neocortical Metabolite Ratio in Patients with Complex Partial Seizure: Short TE and Long TE Techniques Using Single Voxel Proton MR Spectroscopy

PURPOSE: To compare hippocampal and neocortical metabolite ratios using single-voxel proton MR spectroscopy with different echo times in patients with complex partial seizure. MATERIALS AND METHODS: Using a GE Signa 1.5 T scanner with STEAM and PRESS sequences, automated single voxel proton MRS was used to determine metabolite ratio differences in the hippocampus and neocortex of nine complex partial seizure patients [mesial temporal sclerosis (n=5), status epilepticus (n=1), tumor (n=1), cortical dysplasia (n=1), occipital lobe epilepsy (n=1)]. A total of 20 examinations were performed in the region of the hippocampus (n=17), temporal neocortex (n=1), and parieto-occipital gray matter (n=1). Voxel size range was 5.2 -17.4 cm 3. The calculated creatine (Cr) peak was employed as an internal reference and the relative ratio of N-acetylaspartate (NAA) and choline (Cho) was calculated for both short and long echo times using an automated PROBE/SV (GE Medical Systems) package. Each NAA/Cho ratio obtained using both PRESS and STEAM techniques was compared by means of statistical analysis (paired Student t-test). RESULTS: Using PRESS (long TE, 272 ms), NAA/Cho ratios were successfully calculated in 16 of 20 examinations; in four this was not possible due to noise levels of the Cr and Cho peaks. Using STEAM (short TE, 30 ms) NAA/Cho ratios were successfully calculated in 19 of 20 examinations; in one, the Cho peak could not be measured. Using PRESS and STEAM, mean and standard deviations for the NAA/Cho ratio were 1.22 +/-0.50 and 1.16 +/-0.36, respectively. There were no statistically significant differences in this ratio between the short and long TE method (p <0.01). CONCLUSION: In complex partial seizure patients, no significant metabolite differences were found between short and long echo times of single voxel proton MR spectroscopy. The metabolite ratio at different echo times can be reliably obtained using this simplified and automated PROBE/SV quantitation method.

Diffusion Weighted MR Imaging of Transient Ischemic Attacks

PURPOSE: To investigate the findings of diffusion-weighted MR imaging in patients with transient ischemic at-tacks (TIA). MATERIALS AND METHODS: Between August 1996 and June 1999, 41 TIA patients [M:F = 28:13, mean age 57 (range, 27 -75) years] with neurologic symptoms lasting less than 24 hours underwent diffusion-weighted MR imaging. The time interval between the onset of symptoms and MR examination was less than one week in 29 patients, from one week to one month in eight, and undetermined in four. Conventional MR and DWI were compared in terms of location of infarction and lesion size (3 cm), and we also determined the anatomical vascular territory of acute stroke lesions and possible etiologic mechanisms. RESULTS: The findings of DWI were normal in 24/41 patients (58.5%), while 15 (36.6%) showed acute ischemic lesions. The other two showed old lacunar infarcts. All acute and old DWI lesions were revealed by conven-tional MR imaging. Among the 15 acute stroke patients, seven had small vessel lacunar disease. In three pa-tients, the infarction was less than 1 cm in size. Six patients showed large vessel infarction in the territory of the MCA, PCA, and PICA; the size of this was less than 1 cm in three patients, 1 -3 cm in two, and more than 3 cm in one. In two patients, embolic infarction of cardiac origin in the territory of the MCA and AICA was diagnosed. CONCLUSION: The possible mechanism of TIA is still undetermined, but acute lesions revealed by DWI in TIA patients tend, in any case, to be small and multiple.

Functional MR Imaging in the Patients with Complex Partial Seizures

PURPOSE: To evaluate the clinical usefulness of functional MR imaging (fMRI) for localization of the cerebral motor and sensory cortices and the language center in patients with complex partial seizure. MATERIALS AND METHODS: A total of 47 fMRIs were obtained in 14 patients (M:F=9:5; age 15 -50 years; 13 right handed and 1 ambidextrous) with complex partial seizure (6 temporal lobe epilepsy, 6 frontal lobe epilepsy, 1 occipitotemporal lobe epilepsy, 1 hemispheric epilepsy). Conventional MR imaging revealed no abnormality in four patients, localized cerebral atrophy in one, hippocampal sclerosis in four, and benign neoplasm in the remaining five. fMRI was performed on a 1.5 T MR scanner (GE Signa Horizon) using gradient-echo single-shot EPI. Nineteen fMRIs were obtained in eight patients who performed the language task, 16 fMRIs in ten who performed the motor task and 12 fMRIs in ten who performed the somatosensory task. The activation task consisted of three language tasks (silent picture naming, word generation from a character, categorical word generation), motor tasks (opposition of thumb and index finger for hand/dorsiflexion or extension for foot), and sensory tasks (passive tactile stimulation of hand or foot using a toothbrush). The data were analyzed using z-score (p<0.05), clustering, and cross-correlation analysis based upon homemade software, IDL 5.1. The success rate for obtaining meaningful fMRI was evaluated and activated regions were assessed on the basis of each fMRI obtained during language, motor, and omatosensory tasks. fMRI findings were compared with those of the Wada test (n = 7) for language lateralization and with invasive cortical mapping (n = 3) for the localization of eloquent cerebral cortex, especially around the central sulcus. RESULTS: The overall success rate of fMRI was 79 % (37/47); success rates of fMRI with language, sensory, and motor tasks were 89 % (17/19), 83 % (10/12), and 63% (10/16), respectively. Areas activated during language tasks (n=17) included the dorsolateral prefrontal cortex (16/17), anterior cingulate gyrus (16/17), posterior parietal area (15/17), Wernicke's area (10/17), and Broca's area (8/17). Regions activated by motor and somatosensory tasks (n=20) included the central sulcus (16/20), prefrontal cortex (15/20), posterior parietal cortex (9/20), supplementary motor area (6/20), and temporal cortex (3/20). The results of fMRI were concordant with the Wada test in six of seven subjects (86%) for language lateralization of left hemispheric dominance and with invasive cortical mapping in two of three patients (67%) for localization of the motor and sensory cortices. CONCLUSION: fMRI was successful in approximately three-quarters of patients with complex partial seizure, but at present appears to be an inadequate alternative to current invasive studies. Further clinical investigation is needed.

A new method of radiological visualization of internal iliac lymph nodes in carcinoma of the uterine cervix; lymphatic enhanced CT scan

Preoperative evaluation of metastasis to internal iliac lymph nodes are very important in the designing of the patient's therapeutic plan and the predicting the prognosis of carcinoma of the uterine cervix. Until now no study has reported on the subject of selective visualization of the internal iliac lymph nodes. Indirect lymphangiography is a simple method for evaluating local lymphatic system. The internal iliac lymph nodes can be visualized by combining indirect lymphangiography of the upper one-third area of the vagina and thin section CT scan. We applied this method to 25 cases of FIGO B and A stage of the carcinoma of the uterine cervix, and correlated our findings with results of radical abdominal hysterectomy, We were able to visualize the internal iliac lymph nodes in 24 cases out of 25, and their size range was 3-15 mm. No nodal metastasis were found in all the patients and these were varified by subsequent pathologic examination from radically dissected lymph nodes.