Comparison of postmortem magnetic resonance imaging and neuropathologic findings in the cerebral white matter.

Two types of high-signal intensity abnormalities are frequently found bilaterally in the cerebral white matter of brains of elderly patients on T2-weighted magnetic resonance imaging (MRI) scans. One is located in the immediate periventricular region; the other, in the deep subcortical white matter (centrum semiovale). The diagnostic implications of this second type continue to be uncertain. To determine the neuropathologic correlates of these lesions, the brains from seven elderly patients were fixed in buffered formaldehyde solution, subjected to MRI scanning, and examined neuropathologically. Variable degrees of bilateral periventricular (subependymal) sharply defined areas of high-signal intensity were found in all the brains, and the larger of these showed corresponding areas of myelin pallor with gliosis and dilated perivascular spaces. Discrete bilateral patches of high-signal intensity were found in the centrum semiovale in five patients. Myelin and axon stains showed varying degrees of diffuse white matter pallor in many areas examined, both with and without these areas of high-signal intensity on MRI scans. Neither the myelin nor the axon stains showed discrete white matter abnormalities that corresponded to the MRI findings. We believe that these changes, so commonly found on MRI scans in the elderly, reflect actual changes in the white matter but that their nature and clinical significance need to be elucidated.

Poor prediction of positive computed tomographic scans by clinical criteria in symptomatic pediatric head trauma.

A retrospective study of 98 children who received CT scanning for head trauma was conducted to determine whether clinical signs would accurately identify patients needing CT scans. The clinical findings of Glasgow Coma Scale score of 12 or less, altered consciousness on admission, and focal abnormalities on neurologic examination were each significantly associated with abnormal findings on CT scans (P less than .01). However, 31% of the 51 patients with Glasgow Coma Scale scores greater than 12 had abnormal CT scan findings. No clinical findings, alone or in combination, accurately identified all patients with abnormal findings on CT scans.

CT and MR of angiomatous malformations of the choroid plexus in patients with Sturge-Weber disease.

Eight patients with Sturge-Weber disease were evaluated by CT (six patients), MR (one patient), or both (one patient). CT scans of five of seven patients showed enlargement and increased enhancement of the choroid plexus on the same side as the facial and intracranial lesions. MRI showed similar findings in both patients examined. This enlargement, seen in six of eight cases of Sturge-Weber disease, is compatible with the presence of angiomatous malformations of the choroid plexus. It appears to be a common finding in this disease.

CT diagnosis of toxic brain injury in cyanide poisoning: considerations for forensic medicine.

Two deaths occurred after ingestion of cyanide-containing Extra-Strength Excedrin capsules. Cranial CT scans obtained within 3 hr of each patient's collapse showed diffuse cerebral swelling and loss of gray-white differentiation. Most diffuse cerebral insults (hypoxia, ischemia) do not show such changes so soon after injury. The early onset of diffuse cerebral edema with loss of gray-white differentiation may be a clue to the diagnosis of acute cyanide poisoning.

CT of acquired hyperopia with choroidal folds.

Seven patients with an ophthalmologic diagnosis of acquired hyperopia with choroidal folds were evaluated by high-resolution axial CT of the orbits. Coronal, oblique coronal, and parasagittal reformations were obtained and the thickness of the optic nerve and morphologic appearance of the globes were assessed by measurement and subjective appearance. Flattening of the globe, which caused the globe to assume an ellipsoid shape, was seen in all 11 affected eyes. Mild to moderate optic nerve enlargement was also demonstrated in most patients. In six of 11 affected eyes a visible space was noted between the optic nerve and its sheath, implying expansion of the subarachnoid perineural compartment. These findings were not demonstrated in a control group of five patients scanned in a similar manner. Scans of a phantom revealed no evidence of CT-generated distortion. These findings may help to identify hyperopia with choroidal folds as a benign disease and eventually help to establish its cause.

Blinded comparison of cranial CT and MR in closed head injury evaluation.

PURPOSE: To compare CT and MR in the evaluation of acute head injury. METHODS: One hundred seven consecutive patients who were referred to the emergency department and underwent both MR and CT cranial examinations within 48 hours were retrospectively reviewed. The films were interpreted by two neuroradiologists blinded to all patient information. RESULTS: The sensitivity of MR was significantly higher than that of CT for the detection of contusion, shearing injury, subdural and epidural hematoma, and sinus involvement. The sensitivity of CT was significantly higher than that of MR for the evaluation of fracture. The sensitivities of MR and CT were statistically equivalent for the detection of superficial soft-tissue injury. The overall sensitivity of MR for the detection of abnormalities in acute head trauma was 96.4%, and for CT was 63.4%. CONCLUSIONS: CT and MR are complementary studies in the evaluation of acute head trauma. MR is necessary to define or exclude contusions, deep shearing injury, and extraaxial fluid collections in acute head trauma.

Multicenter study of gadopentetate dimeglumine as an MR contrast agent: evaluation in patients with spinal tumors.

In an open-label, multicenter study, the efficacy and safety of gadopentetate dimeglumine (0.1 mmol/kg) administered IV as an MR imaging contrast agent were evaluated in 113 patients with symptoms of spinal tumors. The examinations were performed with a variety of imagers at different field strengths. Scans with short and long TRs were obtained in all patients before and after IV administration of the contrast medium. Contrast enhancement was seen in 77% of patients. No enhancement was seen in 23%, but this absence was useful diagnostic information in all cases. In 66% of the cases, additional information regarding location, size, configuration, and/or characterization of the lesion was obtained from postcontrast scans. The investigators made a change from referral diagnosis to postinjection diagnosis in 30% of the cases. Postinjection images provided additional information in 96% (43/45) of intradural extramedullary and intramedullary tumors; it also provided additional information in 20 (53%) of 38 cases of extradural tumor. Gadopentetate dimeglumine demonstrated a high level of safety and tolerance, as evidenced by the lack of clinically significant trends toward abnormal changes from baseline evaluations for physical and neurologic examinations, vital signs, and hematologic and blood chemistry parameters and by the low prevalence and mild nature of adverse reactions. Gadopentetate dimeglumine was found to be efficacious in the evaluation of suspected spinal tumors. High levels of safety and tolerance were demonstrated.

CT infusion scanning for the detection of cerebral aneurysms.

Computerized tomography (CT) infusion scanning can confirm the presence or absence of an aneurysm as a cause of spontaneous intracerebral hemorrhage. Eight patients who presented with spontaneous hemorrhage were examined using this technique. In five patients the CT scan showed an aneurysm which was later confirmed by angiography or surgery; angiography confirmed the absence of an aneurysm in the remaining three patients. This method is an easy effective way to detect whether an aneurysm is the cause of spontaneous intracerebral hemorrhage.

Adult "congenital" bilateral occlusion of the foramina of Monro.

Bilateral occlusion of the foramina of Monro was detected and treated in a hydrocephalic adult who developed rapid striking recent memory loss. She was treated by midline windowing of the third ventricle into the dilated lateral ventricles at a location 2 cm posterior to the occluded foramina of Monro. No inflammation was present. A biopsy specimen showed no evidence of malignancy. A reservoir was placed for long-term measurement of intraventricular pressure. Ten-year follow-up with pressure measurements, serial computed tomography scans, and magnetic resonance imaging showed no evidence of tumor.

Jugular vein obstruction caused by turning of the head.

In vivo and cadaver studies demonstrated that turning the head to one side results in torsion and compression of the ipsilateral internal jugular vein. This can obstruct venous drainage from the head and cause increased intracranial pressure in patients who have had ligation or resection of the contralateral jugular vein or who have maldevelopment of the contralateral dural sinuses.

Nuclear magnetic resonance imaging. Applications in the diagnosis of cerebrospinal diseases.

The applications of the important new diagnostic modality, nuclear magnetic resonance (NMR) imaging (or MRI), to the diagnosis of diseases of the central nervous system (CNS) are discussed. Specific examples of NMR imaging of cerebral and spinal tumours, infarction, demyelination and subdural haematomas are illustrated and compared with corresponding CT scans. The greater sensitivity of NMR, together with its ability to image in axial, coronal and sagittal planes, suggests that NMR will replace CT for many diagnostic investigations of the CNS.

High-resolution CT scanning in the evaluation of cervical spine fractures: comparison with plain film examinations.

Forty-nine patients with cervical spine fractures were identified among 160 patients who underwent CT of the cervical spine for blunt trauma. Although there was a high index of suspicion on the plain film interpretation, as well as a large percentage of false positives, many fractures were found on CT that were not suggested, even in retrospect, on the plain radiographs. Of the 136 fractures ultimately identified in these patients, CT detected 135 (99%) while only 64 (47%) were seen or suspected on the initial screening radiographs. At first glance, this might appear to discredit the plain films as a screening device. However, most of these "occult" fractures occurred in vertebrae that had been identified as probably fractured in other parts, for example, pedicle fractures found in vertebrae initially suspected of harboring only a vertebral body fracture. Most of the remainder of the uncovered fractures were in vertebrae immediately adjacent to ones that were initially identified as fractured. Indeed, of the 49 patients with fractures, only one had an adequately exposed and positioned plain film that was completely normal. The ability of CT to determine quickly and confidently the presence or absence of cervical fractures and to define the position of fragments in relation to the spinal canal is of considerable value in the medical and nursing management of the seriously traumatized patient. For example, when a fracture is seen or suspected on conventional films, a limited CT examination of the area is recommended. Plain films should be used to guide the CT examination so that an intact vertebra above and below the lesion is included. If an adequately exposed and positioned plain film series of the cervical spine is normal, it is unlikely that CT will reveal a fracture. While conventional radiographs fail to detect a surprising number of fractures, they retain their value as a screening tool and as a guide to selective CT imaging.

Gadolinium-DTPA-enhanced MR imaging of spinal neoplasms: preliminary investigation and comparison with unenhanced spin-echo and STIR sequences.

Unenhanced T1- and T2-weighted spin-echo, short inversion time inversion recovery (STIR), and gadolinium-DTPA (Gd-DTPA)-enhanced spin-echo and STIR imaging techniques were used in 20 patients as part of a multicenter study to assess the safety and efficacy of Gd-DTPA in spinal imaging. Five patients had normal MR scans. Of those with lesions, both Gd-DTPA-enhanced T1-weighted spin-echo and unenhanced STIR scans improved detection and evaluation of spinal tumors over conventional spin-echo methods, particularly T2-weighted spin echo, by providing higher tissue contrast in shorter imaging times. The Gd-DTPA-enhanced T1-weighted spin-echo scans were most helpful in evaluating intradural tumors, whereas STIR sequences were most effective for extradural tumors and bone metastases. In most cases, Gd-DTPA-enhanced T1-weighted spin-echo scans best delineated tumor margins, and the enhancement was helpful in suggesting a cellular or active nature of the lesions. In some cases, the enhancement resulted in a more homogeneous and thus less abnormal-appearing marrow in vertebrae involved by tumor; therefore, a precontrast T1-weighted spin-echo scan is necessary in all patients who are to be studied with Gd-DTPA. A combined approach that uses T1-weighted spin-echo, Gd-DTPA-enhanced T1-weighted spin-echo, and STIR images currently appears optimal for MR imaging of spinal neoplasms. T2-weighted spin-echo images add information only in occasional cases.

The natural history and CT appearance of acquired hyperopia with choroidal folds.

Seven healthy adults with acquired hyperopic change in refractive error had choroidal folds in affected eyes. High resolution computerized tomographic scanning techniques used to obtain coronal, oblique coronal, and parasagittal reformations revealed flattening of the posterior globes and mild to moderate optic nerve enlargement. In 5 of 11 eyes, a space was noted between the optic nerve and its sheath, implying expansion of the sub-arachnoid perineural compartment. The clinical findings and natural history of this syndrome, based on an average follow-up of 4.5 years, are discussed.

Comparison of CT, low-field-strength MR imaging, and high-field-strength MR imaging. Work in progress.

To assess objectively the sensitivity and specificity of low-field-strength (0.064 T) magnetic resonance (MR) imaging, a prospective blind study of 280 examinations was performed to compare low-field-strength MR imaging with computed tomography (CT) and with high-field-strength (1.5-T) MR imaging of the cranium. The sensitivity (defined as the true-positive rate) with high-field MR imaging was superior to that with low-field MR imaging and CT in helping detect overall abnormalities. Sensitivities were generally similar over a broad range of specific cranial central nervous system diseases. Low-field and high-field MR imaging were equivalent in the blind diagnoses of neoplasms and white matter disease, whereas low-field MR and CT were equivalent in the blind diagnoses of contusion, subdural and epidural hematoma, sinus disease, normality, and abnormality. The specificities with low-field MR imaging and CT were substantially better than those with high-field MR imaging.

Abnormal corpus callosum: a sensitive and specific indicator of multiple sclerosis.

The authors investigated whether identification of corpus callosal (CC) involvement might increase the specificity of magnetic resonance (MR) imaging in differentiating multiple sclerosis (MS) from other periventricular white matter diseases (PWDs). They prospectively evaluated 42 patients with MS and 127 control patients with other PWDs. Ninety-three percent of the MS patients demonstrated confluent and/or focal lesions involving the callosal-septal interface (CSI). These lesions characteristically involved the inferior aspect of the callosum and radiated from the ventricular surface into the overlying callosum. CSI lesions were optimally demonstrated on sagittal long repetition time (TR)/short echo time (TE) images and frequently (45% of cases) went undetected on axial images. Only 2.4% of the control patients had lesions of the CC. The authors conclude that midsagittal long TR/short TE images are highly sensitive and specific for MS and that callosal involvement in MS is more common than previously reported.

Early diagnosis of spinal metastases by CT and MR studies.

Fifteen patients with known metastatic or high-risk primary cancer, normal neurologic examinations, and new abnormalities on 99mTc bone scan were evaluated with spinal CT and magnetic resonance (MR) imaging. Four patients underwent CT metrizamide myelography. Spinal CT and MR agreed in 14 of 15 patients demonstrating spinal metastases in 12 patients and benign disease in two. In one patient spinal CT was normal, but MR showed altered marrow signal consistent with metastatic disease. Epidural tumor was demonstrated by CT metrizamide myelography in four cases, all correctly identified by MR. Further evaluation of spinal MR in this setting is warranted.

MR imaging of periventricular leukomalacia in childhood.

Eight children with clinical and radiologic abnormalities consistent with periventricular leukomalacia were investigated with MR imaging of the brain that employed both inversion-recovery and T2-weighted spin-echo imaging sequences. The more precise delineation of white and gray matter on inversion-recovery images as compared with CT allows a detailed demonstration of the anatomic features of periventricular leukomalacia; specifically, a reduced quantity of white matter in the periventricular region and centrum semiovale and, in more severe cases, cavitated infarcts that replace the immediate periventricular white matter. The T2-weighted spin-echo and short inversion time inversion-recovery images demonstrated abnormally increased signal in white matter that appeared normal on CT scans and only minimally abnormal on conventional inversion-recovery images. These abnormalities most probably represent white matter gliosis that extends beyond the immediate periventricular regions. MR recognition of cerebral white matter abnormalities associated with periventricular leukomalacia may confirm the clinical suspicion of this diagnosis in children with spastic diplegia or quadriplegia.