Search

Objective: The purpose of this study is to discuss the evidence supporting the use of neuroimaging in adult patients presenting with new-onset seizure., Conclusion: Unenhanced CT should be the initial imaging examination performed for adults presenting with first unprovoked seizure in the acute setting to exclude conditions requiring urgent or emergent intervention. MRI has added benefits and should be considered for adults presenting acutely for whom the initial CT is negative and for those presenting with new-onset seizure in the nonacute setting.

Objective: Brain arteriovenous malformation (AVM) rupture results in substantial morbidity and mortality. The goal of AVM treatment is eradication of the AVM, but the risk of treatment must be weighed against the risk of future hemorrhage., Conclusion: Imaging plays a vital role by providing the information necessary for AVM management. Here, we discuss the background, natural history, clinical presentation, and imaging of AVMs. In addition, we explain advances in techniques for imaging AVMs.

Objective: The purpose of this study was to examine the frequency of change in size of pineal cysts on serial MR studies., Materials and Methods: Thirty-two patients (19 females, 13 males) with a diagnosis of pineal cyst at any time who underwent brain MR imaging more than once in a period of at least 6 months were identified by computerized search of radiology reports. Four patients underwent MR imaging to follow up pineal cysts, whereas the remaining patients were imaged for a variety of indications, including intracerebral neoplasms. Measurements of maximal cyst dimension on both initial and latest follow-up studies were obtained in all patients, and cyst volumes were calculated in 23 patients., Results: Length of follow-up ranged from 6 months to 9 years. All cysts were considered incidental and none were treated. Maximal cyst dimensions ranged from 0.5 to 2.2 cm. On average, there was no significant change in cyst volume. The maximal dimension of the cyst did not change in 24 (75%) of 32 patients. Two cysts resolved completely on follow-up, three cysts decreased by 2-4 mm, two cysts enlarged by 2-3 mm, and one cyst formed and grew to 1.2 cm., Conclusion: Whereas the size of pineal cysts as a whole remained unchanged on serial MR studies, cysts may either form or involute in individual patients. Small increases in cyst size did occur but were not associated with specific clinical findings. These findings suggest that typical pineal cysts may be followed up on a clinical basis alone rather than on imaging.

Objective: The purpose of our study was to test the hypothesis that the apparent diffusion coefficient (ADC) of normal-appearing white matter increases with advancing age., Subjects and Methods: We selected 38 patients with normal MR imaging findings from 332 patients undergoing clinical MR imaging. Diffusion-weighted MR imaging was performed with diffusion gradients applied in three orthogonal directions. For each patient, the average ADC on trace-weighted diffusion images of white matter at prespecified regions of interest and at the thalamus were compared with the patient's age., Results: For the white matter, ADC sorted by patient age in decades increased with advancing age. Patients at least 60 years old had significantly higher ADC (0.769 +/- 0.019 mm(2)/sec x 10(-3)) than patients less than 60 years old (0.740 +/- 0.013 mm(2)/sec x 10(-3)) (p < 0.001). Comparison of individual white matter ADC and age showed a significant increase with advancing age (p < 0.0001). For the thalamus, the average ADC among patients at least 60 years old (0.766 +/- 0.015 mm(2)/sec x 10(-3)) exceeded the average ADC for patients less than 60 years old (0.745 +/- 0.022 mm(2)/sec x 10(-3)) (p < 0.05). However, comparison of individual thalamic ADC and patient ages, although showing a trend to higher ADC with increasing age, did not reach statistical significance (p = 0.06)., Conclusion: Advancing age is associated with a small but statistically significant increase of water diffusibility in human white matter. A similar trend was present in the thalamus. These increases may reflect mild structural changes associated with normal aging.

Objective: The purpose of this study was to compare MR imaging features of gangliogliomas in children less than 10 years old with those seen in patients at least 10 years old., Materials and Methods: Our study population consisted of 15 female patients and 10 male patients with a mean age of 20 years. The early childhood group was composed of six children with a mean age of 5.5 years. The older group was composed of 19 patients with a mean age of 25.6 years. We assessed tumor volume, tumor location, percentage of tumor that was cystic, pattern of contrast enhancement, and degree of edema., Results: The temporal lobe was the most common tumor location in both groups. Mean tumor volume in the early childhood group was 83 cm3, which was significantly larger than the mean tumor volume (9.78 cm3) for the older group (p = 0.001). Cystic tumors were more common in the early childhood group (83%) than in the older group (63%), and the average percentage of cysts in the cystic tumors was much higher in the early childhood group (67%) than in the older group (30%). Contrast enhancement was seen in five of six early childhood tumors and 13 of 16 tumors in older patients. Four of six tumors in the early childhood group and five of 19 tumors in the older patient group had associated edema., Conclusion: The mean tumor volume of gangliogliomas in the early childhood group was significantly larger than that of the older patient group. This finding may be indicative of differences in tumor growth patterns in the two groups, ability of the hemicranium to adjust to mass effect in childhood, or sampling error as a result of a relatively small sample size.

This review has highlighted some of the disease processes that produce diagnostic difficulty in the emergency neuroradiology setting. Because radiologists are often the first individuals to consider these entities, they must be familiar with the clinical features that suggest the diagnosis. Furthermore, acquaintance with the various imaging findings of these diseases will allow early diagnosis and will help limit the severe complications that follow these neurologic emergency conditions if left untreated.

The major clinical use of diffusion-weighted imaging to date has been in evaluation of cerebral infarction, at which it excels. However, diffusion-weighted imaging has also shown promise for other applications, ranging from quantitative analysis of biologic changes that are not apparent from simple visual inspection of images (but are detectable after using regions of interest on apparent diffusion coefficient maps) to better characterization of other intracranial abnormalities (e.g., abscess and tumor). Both the clinical and research applications of diffusion-weighted imaging can be expected to increase, providing fresh insights into physiologic characteristics of both normal and abnormal tissue.

Objective: Our aim was to determine whether the contrast between white matter lesions and normal-appearing white matter in fast spin-echo fluid-attenuated inversion recovery (FLAIR) images can be improved by lengthening the effective TE and the echo train length., Subjects and Methods: Thirty patients with various white matter lesions were imaged using fast spin-echo FLAIR sequences (TR = 10,002 msec; inversion time = 2200) on a 1.5-T MR imaging system. For 14 patients, fast spin-echo FLAIR sequences with a TE of 165 msec and echo train length of 32 (fast spin-echo FLAIR 165/32) were compared with fast spin-echo FLAIR sequences with a TE of 125 msec and echo train length of 24 (fast spin-echo FLAIR 125/24). For 16 other patients, fast spin-echo FLAIR 165/32 sequences were compared with fast spin-echo FLAIR sequences with a TE of 145 msec and echo train length of 28 (fast spin-echo FLAIR 145/28). Signal difference-to-noise ratios were calculated between the lesions and normal-appearing white matter for a typical lesion in each patient., Results: In both groups, a small but statistically significant increase in the signal difference-to-noise ratio was found on the fast spin-echo FLAIR sequences using the longer TE and echo train length. In the first group, signal difference-to-noise ratio increased from 18.7 +/- 4.7 (mean +/- SD) for fast spin-echo FLAIR 125/24 to 20.1 +/- 4.5 for fast spin-echo FLAIR 165/32 (p < .05). In the second group, the signal difference-to-noise ratio increased from 15.4 +/- 4.0 for fast spin-echo FLAIR 145/28 to 16.8 +/- 4.6 for fast spin-echo FLAIR 165/32 (p <.01). In addition, fast spin-echo FLAIR sequences with a longer TE and echo train length were obtained more rapidly (6 min for fast spin-echo FLAIR 125/24, 5 min 20 sec for fast spin-echo FLAIR 145/28, and 4 min 41 sec for fast spin-echo FLAIR 165/32)., Conclusion: Lengthening the TE to 165 msec and echo train length to 32 in fast spin-echo FLAIR imaging allows both a mild improvement in the contrast between white matter lesions and normal-appearing white matter and shorter imaging times.

Objective: The purpose of this study was to correlate 18F-fluorodeoxyglucose positron emission tomography (PET) and MR imaging features of cerebral gangliogliomas before and after PET-MR image registration., Conclusion: After registration of PET and MR images, all six gangliogliomas in our series were shown to have heterogeneous metabolic activity. Areas of hypermetabolic activity were seen in all lesions. In five of the six cases, PET-MR image registration provided information regarding tumor metabolism that was not available on nonregistered hard-copy examinations.

Objective: The purpose of this study was to report the association of dural sinus thrombosis with a hypercoagulable state associated with activated protein C resistance., Conclusion: In our small study population, hemorrhagic venous infarction was common (three of four patients) among patients with dural sinus thrombosis and activated protein C resistance. Four of five patients with dural sinus thrombosis had positive tests for activated protein C resistance. This finding, in conjunction with data from other studies, suggests that patients with dural sinus thrombosis may need to be studied for the presence of activated protein C resistance. A positive finding for activated protein C resistance can be important not only in helping to explain the cause of thrombosis in affected individuals but also in identifying families at risk for thrombosis.

Objective: The purpose of this study was to determine the patterns of non-CNS thromboses in patients with a hypercoagulable state associated with antiphospholipid antibodies (APA)., Materials and Methods: A search of our institution's clinical coagulation and immunology laboratories' records of patients examined from January 1993 to January 1996 revealed 1290 patients with APA. Computerized records of radiologic studies were reviewed for evidence of thrombotic events, which were found in 93 patients (49 males and 44 females; average age, 40 years). The anatomic distribution of thrombotic events was recorded., Results: Fifty-five patients (59%; 29 males and 26 females; average age, 44.2 years) had solely venous thromboses, 26 patients (28%; 15 males and 11 females; average age, 33.1 years) had solely arterial thromboses, and 12 (13%; 5 males and 7 females; average age, 35.4 years) had both types of events. Deep vein thrombosis (DVT) of the legs was the most common finding, occurring in 45 patients (48%). Six patients had recurrent DVT. Other sites of venous thrombotic events included pulmonary embolism, 30 patients (32%); thoracic veins (superior vena cava, subclavian vein, or jugular vein), 10 patients (11%); and abdominal or pelvic veins, 18 events in 11 patients (12%). Sites of arterial thromboses included arteries supplying the upper limbs (great vessels arising from the aorta or the brachial, radial, ulnar, or digital arteries), 15 events in 12 patients (13%); aorta, one patient (1%); abdominal or pelvic arteries, 11 events in eight patients (9%); and arteries supplying the lower limbs (femoral or popliteal arteries), seven patients (8%)., Conclusion: Venous thromboses were more common than arterial thromboses in our patient group, with DVT being the most common. However, thromboses in sites that are unusual for the general population were also relatively common. APA should be suspected in patients with thromboses in unusual sites or recurrent thromboses of an otherwise unexplained cause.

The causes of stroke in young adults differ substantially from those in older adults. In many instances, the diagnosis can be made by taking a clinical history and performing laboratory studies (e.g., in patients who have multiple thromboses associated with anti-phospholipid antibodies). In other circumstances, clues to the diagnosis can be found on routine CT and MR studies. However, in many circumstances, imaging tailored to a specific diagnosis is important (e.g., MR imaging of the neck in patients with suspected arterial dissection). In yet other cases, additional studies (e.g., echocardiography in suspected cardiogenic embolism) are important to establish the cause.

Objective: We categorized the MR imaging characteristics of intracranial epidermoid tumors., Materials and Methods: MR images from 23 cases of intracranial epidermoid tumors were reviewed retrospectively. Signal intensities of tumor relative to surrounding structures were noted, as were the internal architecture of the tumors and the presence and degree of hydrocephalus., Results: Seventeen (74%) of 23 cases of intracranial epidermoid tumors were revealed as slightly hyperintense relative to CSF on T1-weighted MR images. Nineteen (95%) of 20 cases were hyperintense relative to CSF on proton density-weighted MR images. Fifteen (65%) of 23 cases were isointense to CSF on T2-weighted MR images, whereas the remaining eight cases (35%) were hyperintense to CSF on T2-weighted MR images. One (4%) of 23 cases showed signal intensity that was isointense to CSF on all pulse sequences. Fifteen (65%) of 23 cases showed heterogeneous signal characteristics on either T1-weighted or proton density-weighted MR images, or both. Eight (35%) of 23 cases showed a rim of hyperintensity on proton density-weighted MR images. Five (33%) of the 15 cases that received gadolinium showed rim enhancement. Five (22%) of 23 cases were multilocular, with different regions of tumors showing highly variable imaging characteristics. Two (9%) of 23 cases showed high signal intensity on T2-weighted MR images in the adjacent brain parenchyma. Two (9%) of 23 cases showed mild hydrocephalus. Six (43%) of 14 tumors that either originated in or secondarily involved the cerebellopontine angle also extended into the ipsilateral Meckel's cave., Conclusion: On T1-, proton density-, and T2-weighted MR images intracranial epidermoid tumors usually showed heterogeneous signal intensity that was hyperintense to CSF. On all spin-echo pulse sequences epidermoid tumors with signal characteristics isointense to CSF were unusual. Hydrocephalus, even in the setting of marked displacement and compression of the brainstem, was not usually seen on MR imaging. Meckel's cave was often involved secondarily with epidermoid tumors that involved the cerebellopontine angle.

Objective: The purpose of this study was to determine the spectrum of neuroradiologic findings in patients with antiphospholipid antibodies (APA) and to compare findings in systemic lupus erythematosus (SLE) and non-SLE patients., Materials and Methods: We identified 110 patients with APA who underwent CT or MR imaging, of whom 59 (54%) had abnormal studies. Of these 59 patients, abnormalities were categorized as large infarcts, cortical infarcts, lacunar infarcts, hyperintense white matter foci on T2-weighted images, or dural sinus thrombosis. White matter foci were designated as small (< 5mm) or large (> 5 mm)., Results: Large infarcts were the most common abnormality, seen in 24 of 110 (22%) patients, followed in frequency by hyperintense white matter foci, seen in 19 of 110 (17%) patients. Ninety-five percent of patients with hyperintense white matter foci had at least one large lesion, and 76% had five or more small foci, three or more large foci, or both. Small cortical infarcts and lacunar infarcts were seen in 11 of 110 (10%) and 10 of 110 (9%) patients, respectively. Dural sinus thrombosis was seen in five patients. The frequency of abnormalities was high in both the SLE (57%) and the non-SLE (41%) groups. Large infarcts were more common in the non-SLE group (26%) than in the SLE group (5%). Although hyperintense white matter foci and cortical infarcts were more common in SLE patients, the differences were not statistically significant., Conclusion: Infarcts of various sizes and hyperintense white matter foci are the most common abnormalities seen on CT and MR imaging in patients with APA. We found no significant differences in frequencies of abnormalities seen between non-SLE and SLE patients.

Objective: The purpose of this study was to define patterns of Wegener's granulomatosis (WG) orbital disease involvement., Subjects and Methods: We evaluated the orbital examinations of 14 WG patients (CT for nine, MR imaging for three, and both CT and MR imaging for two) for the number of involved orbits, intraconal or extraconal location, involvement of the orbital apex, sinus involvement, bony erosion, and optic nerve compression. MR images were analyzed for signal characteristics and enhancement patterns., Results: We found orbital disease to be unilateral in 12 patients (86%) and bilateral in two patients (14%) (total of 16 orbits). In 11 orbits (69%), coexistent orbital and sinus diseases with bony erosion were present. Orbital disease without sinus disease was seen in five orbits (31%). Intraorbital disease distribution was as follows: solely extraconal--seven orbits (44%) (four with involvement of muscle); intraconal with muscular involvement--one orbit (6%); combined intra- and extraconal--seven orbits (44%); and primarily orbital apex--one orbit (6%). Involvement of the apex was seen in six orbits. The WG mass was hypointense relative to orbital fat on three standard T2-weighted MR images. We saw homogeneous MR contrast enhancement in all four orbits studied on enhanced T1-weighted images., Conclusion: Intraorbital WG involvement is usually accompanied by paranasal sinus disease. A hypointense signal on T2-weighted MR images is helpful in suggesting the diagnosis.

Dissection of either the internal carotid artery or the vertebral artery (cervicocephalic arterial dissection) was once considered uncommon. However, in the past few decades, it has been increasingly recognized as a cause of stroke in young and middle-aged adults. Dissection causes only 0.4-2.5% of all strokes in the general population but causes 5-20% of strokes among young patients. Anticoagulant therapy is usually started immediately after the dissection is diagnosed. The clinical and radiologic features are important to recognize so that anticoagulation therapy can be started promptly, thereby minimizing the risks of infarction, permanent neurologic disability, and death.