Biomedical subjects
Publications and source records attributed to D R Enzmann.
Time-of-flight (TOF) angiography based on inflow enhancement is limited by the steady-state signal differences between blood and the surrounding stationary tissues. We present a new TOF sequence in which magnetization transfer contrast is used to supplement wash-in effects. Angiograms demonstrating the superior performance of this technique are presented.
The authors describe a technique for obtaining angiographic images by means of spiral computed tomography (CT), preprocessing of reconstructed three-dimensional sections to suppress bone, and maximum intensity projection. The technique has some limitations, but preliminary results in 48 patients have shown excellent anatomic correlation with conventional angiography in studies of the abdomen, the circle of Willis in the brain, and the extracranial carotid arteries. With continued development and evaluation, CT angiography may prove useful as a screening tool or replacement for conventional angiography in some patients.
Brain motion during the cardiac cycle was measured prospectively in 10 healthy volunteers by using a phase-contrast cine magnetic resonance (MR) pulse sequence. The major cerebral lobes, diencephalon, brain stem, cerebellum, cerebellar tonsils, and spinal cord were studied. The overall pattern of brain motion showed caudal motion of the central structures (diencephalon, brain stem, and cerebellar tonsils) shortly after carotid systole, with concurrent cephalic motion of the major cerebral lobes and posterior cerebellar hemisphere. Peak brain displacement was in the range of 0.1-0.5 mm for all the structures except the cerebellar tonsils, which had greater displacement (0.4 mm +/- 0.16 [mean +/- standard error of mean]). Caudal motion of the central structures did not occur simultaneously but progressed in a caudal-to-rostral and posterior-to-anterior sequence, being seen first in the cerebellar tonsils and then later in the diencephalon (hypothalamus). Caudal motion of the low brain stem and cerebellar tonsil was simultaneous with caudal motion of cerebrospinal fluid in the cervical subarachnoid space. Oscillatory flow in the aqueduct was delayed compared with brain stem motion.
Fast spin-echo (FSE) magnetic resonance (MR) imaging was compared with conventional, peripherally gated T2-weighted spin-echo (SE) imaging in the detection of high- and low-signal-intensity lesions in the central nervous system. Lesion detectability was determined with percentage of contrast measurements and contrast-to-noise ratios with two different measurements for noise. All three measures of lesion detectability were similar. FSE and SE sequences were quantitatively equivalent in the detection of high-signal-intensity lesions. The SE sequence, however, was superior to the FSE sequence in the detection of small, low-signal-intensity lesions in the central nervous system caused by magnetic susceptibility effects.
A versatile bolusing device made of polystyrene is described for scanning small objects in currently available "air gap" computed tomography scanners. The device, consisting of three concentric rings fitted inside one another, allows for artifact-free and reproducible imaging.
The CT findings in 16 patients with histologically proved primary central nervous system (CNS) reticulum cell sarcoma (RCS) showed this malignancy to have predilection for the basal ganglia and thalamus, the periventricular white matter, the corpus callosum, and the vermis cerebelli. In 43% of patients with untreated tumor it presented as multifocal lesions; in each of these patients the basal ganglia were involved in conjuction with another site. In the other 57% of patients with untreated tumor presenting as solitary lesions the basal ganglia, the corpus callosum, and the frontal lobe were sites of predilection. Such solitary lesions may be indistinguishable from other tumors. Contrast enhancement of RCS was characteristically homogeneous with rare lucency, even in very large lesions.
Simultaneous 111In-DPTA and metrizamide CT cisternography correlated closely in the qualitative imaging of cerebrospinal fluid (CSF) dynamics in 9 normal patients and in 11 patients thought to have communicating hydrocephalus. CSF clearance of both tracers was similar; significant absorption occurred in the spinal dural sac. Although delayed elevated serum iodine levels correlated highly with abnormal persistent ventricular penetration (detection at 48 hours), these levels cannot be used to predict abnormal ventricular stasis. The pattern of ventricular and cortical sulcus enlargement on the plain CT scan did not indicate whether the dynamic metrizamide cisternogram would be normal or abnormal.
Brain abscess evolution was studied in dogs by correlating the CT appearance with the neuropathologic findings. The abscess, produced by direct inoculation, progressed from an area of cerebritis to a well encapsulated abscess over 14 days. Ring enhancement was seen in the cerebritis stage prior to capsule formation. The ring reached its maximum size at this stage and correlated best with the area of cerebritis surrounding the developing necrotic center; the rim of this ring increased in thickness, resulting in progressive diminution of the central lucent area on scans delayed up to 60 min. The diameter of the ring decreased as cerebritis receded. Once the capsule had formed, the central lucent area was similar and no longer filled in on delayed scans.
Cerebral infarction was documented by arteriography and serial computed cranial tomography (CT) in four young adults (ages 16 to 32 years) with migraine. In one case, posterior cerebral artery occlusion produced a deep parietotemporal infarct. The other three cases all had frontotemporal infarcts (one hemorrhagic) in the territory of the middle cerebral artery, without major arterial occlusion. Two infarcts produced lasting neurologic deficits; one was associated with mild, transitory symptoms, and one was asymtomatic. Laboratory investigations in two cases revealed no hematologic or cardiovascular predisposition to cerebrovascular disease. Cerebral infarction, as revealed by CT, may be more prevalent in "complicated" migraine than is generally appreciated. Such lesions may or may not develop in chronologic and anatomic relationship to the headache, and may involve either large or small arteries. The prognosis for functional recovery, based on this limited sample, seems favorable.
Computed tomography's (CT) marked sensitivity to calcium increases its usefulness in the workup of certain ocular lesions. The CT findings in five calcific ocular lesions are described. The relatively limited differential diagnosis of such a finding is discussed.
Extraocular muscle enlargement was symmetrical in 70% and asymmetrical in 30% of patients with Graves' ophthalmopathy. True unilateral muscle involvement occurred in 6%. Computed tomography (CT) showed bilateral orbital involvement in 50% of patients presenting clinically with unilateral eye signs. In patients without a clinically apparent ophthalmopathy, CT demonstrated muscle enlargement in 40%. The medial and inferior rectus muscles were the most frequently and most severely involved. Orbital radiation therapy can result in a decrease in size of involved muscles.
This retrospective study investigated the possible adverse effects of cancer therapy on the brain. Cranial computed tomographic scans of 76 patients with non-central nervous system malignancies and 25 patients with leukemia had enlarged lateral ventricles and/or cortical sulci in 19% and 40%, respectively. Leukemic patients, especially those with meningeal involvement, had the most frequent and most severe abnormalities.
Various contrast agents with either sodium or meglumine cations and iothalamate and diatrizoate anions are compared in a series of patients with malignant gliomas. There is no difference in the ability of these agents to enhance tumors in cranial computed tomography.
Computed tomography proved insensitive to leptomeningeal spread of hematologic malignancies including leukemia, lymphoma, and malignant histiocytosis. In only 3% of patients did it directly demonstrate leptomeningeal tumor. In comparison, the detection rate of leptomeningeal tumor secondary to carcinoma was 44% and for melanoma, 100%. Intracranial subarachnoid seeding from primary brain gliomas was detected in each instance. The simultaneous presence of parenchymal metastases with leptomeningeal carcinomatosis occurred in 18% of patients with nonhematologic malignancies. Computed tomography evidence of communicating hydrocephalus, previously thought to be a major factor in clinical symptomatology, occurred in only 11% of patients.
The CT appearance of metastatic malignant melanoma is varied, but it can show features suggesting the correct diagnosis. Intracerebral hemorrhage alone, associated with an adjacent tumor nodule or mixed diffusely with a tumor, occurred in 10 of 33 patients. Identification of a tumor nodule is important, since it may be the site of recurrent hemorrhage if not removed completely at surgery. Unusual presentations such as meningeal carcinomatosis and lesions simulating primary gliomas also occurred.
The course of 36 patients with medulloblastoma and ependymoma was evaluated prospectively by clinical examination, radionuclide (RN) studies and computed tomography (CT). Seventeen of the 36 patients (47%) had tumor recurrence. Twelve (41%) of the 29 patients with medulloblastoma had recurrent tumors of which 7 of 12 (58%) were at the primary site and 2 of 12 (17%) were within the ventricles while 10 of 12 (83%) were in the subarachnoid space. Five of the 7 patients with ependymoma had recurrent tumors. In 4 of the 5 patients tumor recurred at the primary site while subarachnoid seeding occurred in 2 of 5 patients (40%) and intraventricular metastases were found in 4 of 5 patients (80%). Progressive ventricular enlargement often accompanied subarachnoid seeding, presumably secondary to obstruction of cerebrospinal fluid (CSF) flow in the subarachnoid pathways. CT and RN scans were frequently complementary in detecting tumor recurrence.
A retrospective study of 118 lymphoma patients revealed the computed tomographic brain scan to be sensitive to involvement of the orbit and the brain parenchyma by lymphoma. Brain parenchymal lymphoma was seen only in diffuse histiocytic lymphoma; dural infiltration was less readily detected. Leptomeningeal lymphoma could not be directly demonstrated by the CT scan, even with the use of intravenous contrast medium. Serial CT scans contributed to patient care by differentiating the sometimes confusing nonlymphomatous brain lesions.
On the initial computed tomographic (CT) scan in 10 of 13 patients with herpes simplex encephalitis (HSE), the most characteristic finding was a unilateral, low-density lesion in the medial temporal lobe and/or insular cortex. This lesion was seen in all patients as the disease progressed. When associated with hemorrhage and streaked contrast enhancement this lesion added specificity to the CT scan, but this situation occurred in only 3 patients. Early in the course of HSE, focal CT findings localized the temporal lobe of greatest involvement in 12 patients; 1 had a normal initial CT scan.