Biomedical subjects
Publications and source records attributed to L D Cromwell.
We present two cases of surgically proved colloid cysts that were more apparent on CT scans than on MR images. These cysts, while hyperdense on CT scans, were nearly isointense with brain on multiple MR sequences. This relative lack of visibility represents a potential pitfall when imaging a patient with headache.
Although three-dimensional computed tomographic angiography was developed as a screening tool for use in patients with suspected cerebrovascular disease, this imaging modality has also proven to be of value in surgical planning for patients with large or unusual vascular lesions of the brain. The three-dimensional images generated by this technique yield valuable information regarding the size and configuration of intracranial aneurysms and vascular malformations, the presence and extent of intra-aneurysmal thrombus, the relationship of the vascular lesion to other cerebrovascular or skeletal structures, aneurysm wall thickness, and the presence and orientation of an aneurysm neck. The use of three-dimensional computed tomographic angiography in representative cases of patients with large or unusual cerebrovascular lesions is presented. It has been our experience that this imaging modality displays anatomical information that is not readily available from standard, intra-arterial angiography, provides better detail for surgical planning than magnetic resonance angiography, and is less expensive than either of these other imaging modalities.
Explore the source record for details and available documents.
A patient with paralysis of upward gaze and downward gaze, absent oculocephalic reflexes, and absent vertical saccades also demonstrated intermittent stupor over the first 9 days of presentation. Magnetic resonance imaging (MRI) demonstrated an infarct in the tegmentum of the mesencephalon including the right red nucleus and the periaqueductal area, superior to the oculomotor nucleus, and contiguous through the left thalamus. The infarct included the area around the rostral interstitial nucleus of the medial longitudinal fasciculus (riMLF), as well as the midbrain reticular formation. Mechanisms are proposed for the unusual concurrent sign of intermittent unresponsiveness in this case.
Computer-generated three-dimensional reconstruction of the intracranial vascular system obtained by contrast-enhanced computerized tomography (CT) has been used in the diagnosis of 20 patients with known or suspected intracranial cerebrovascular disease. This technique allows visualization of the intracranial vasculature without exposing patients to the risks associated with intra-arterial angiography. The color prints and videotape images generated have been used to diagnose the presence of intracranial aneurysms, arteriovenous malformations, and venous angiomas. They have also been used to rule out structural abnormalities in patients with suspected intracranial vascular pathology and to screen patients with a strong family history of intracranial aneurysm. In 11 patients who underwent both three-dimensional CT angiography and intra-arterial angiography, the diagnostic correlation was 100%. No complications from the procedures or from incorrect diagnosis have been encountered. Although this technique requires further development and clinical evaluation, the authors' early experience with three-dimensional CT angiography suggests that this may become a valuable tool in the diagnosis of patients with cerebrovascular disease.
A new method of filtering MR images is presented that uses wavelet transforms instead of Fourier transforms. The new filtering method does not reduce the sharpness of edges. However, the new method does eliminate any small structures that are similar in size to the noise eliminated. There are many possible extensions of the filter.
Lhermitte-Duclos disease is a rare disorder characterized by a slowly enlarging mass lesion in the cerebellum. The pathophysiology of the disease is poorly understood, but recent reports have suggested that a clinically significant mass may recur many years after total gross removal of the tumor. Computed tomography and angiography have been relatively insensitive in imaging the tumor either at presentation or during the postoperative period. The authors present three patients with histologically proven Lhermitte-Duclos disease who have undergone magnetic resonance imaging (MRI). In the first case, preoperative T1- and T2-weighted images clearly demonstrated the location and extent of the lesion, which was verified at operation. In the other two cases, only postoperative images were obtained. These demonstrated the extent of residual tumor and indicate a high probability of lesion expansion during periods of 4 and 10 years, respectively. We conclude that MRI is an important tool in both the diagnosis and the treatment of patients with Lhermitte-Duclos disease.
Many MR artifacts are not understandable in terms of previous imaging experience. A variety of artifacts is presented here; their origins and elimination are discussed.
Newer methods of radiation therapy for treating oligodendroglioma after surgical resection have produced promising results using high doses of radiation. However, these doses are close to those that cause necrosis of normal brain, making the accurate spatial localization of tissue at risk for containing tumor cells more important. Because MR imaging is superior to CT in detecting some types of intracranial disease, nine patients with oligodendroglioma were studied with both MR and CT. Results were compared with surgical findings. In six cases, MR identified some tumor volume found during surgery that was not detected by CT. In addition, the interface between abnormality (tumor plus edema) and normality was depicted much more clearly by MR than by CT in most cases. Such superior depiction of the margins of abnormality is important for radiation therapy planning because of the known tendency of oligodendroglioma to infiltrate adjacent edema, making all areas of abnormality potential tumor-bearing tissue. Finally, MR showed normal brain tissue in areas considered suspicious by CT, because they were not well seen on CT in several patients. In these cases of low-grade oligodendroglioma, MR was believed to be superior to CT in providing information needed for radiation therapy planning because of its ability to distinguish tumor and adjacent edema (considered tissue at risk for containing microscopic tumor) from contiguous normal brain.
In a patient with cerebrotendinous xanthomatosis, magnetic resonance imaging (MRI) revealed findings of demyelination in the cerebral white matter, which was also hypodense on CT. The MRI abnormality seemed to be clinically significant in this patient with progressive dementia and abnormal gait.
A toxicologic-pathologic study of isobutyl-2-cyanoacrylate (Bucrylate) was carried out first in dogs and then in humans whose arteriovenous malformations were infused with this embolic agent. The canine specimens obtained at 7, 18, 28, and 147 days after embolization showed the development of a mild histiocytic giant cell reaction, which evolved to end-state sclerotic arteritis. The response was confined to the vessels and did not involve contiguous parenchymal tissues. Ten human specimens, obtained from 1 hr to 7 years after treatment, showed a similar bland reaction with no evidence of suppuration or premalignant changes.
Magnetic resonance (MR) imaging may provide information about tumor location, extent, and margins unavailable from other imaging modalities. The impact of MR on radiation therapy planning was investigated in this study. Thirty patients about to undergo radiation therapy underwent routine radiography and computed tomography (CT) to define the extent of their disease. A radiation therapy plan, including portal placement and size, was drawn up based on this information alone. The patients also underwent MR studies. After the original therapy plan was created, the MR study results were made available to the radiation therapist. In 53% (16/30) of the cases, MR information led to a measurable change in the therapy plan; in an additional 33% (10/30), MR information increased confidence in the original plan. MR may become a necessary procedure for radiation therapy planning in many cases.
Using our modification of the vein patch technique, we created 16 aneurysms in the common carotid arteries of dogs. After a stabilizing and healing period, these aneurysms were treated using percutaneous catheter techniques. Coaxial microcatheters were placed into the aneurysms, and a mixture of isobutyl 2-cyanoacrylate and tantalum dust was infused through the microcatheter using real time fluoroscopic control. Fifteen of the 16 aneurysms were successfully occluded; 1 was a failure because of total occlusion of the carotid artery. One human facial artery aneurysm was similarly treated. The ease and technical details of the treatment are discussed. Although the results are encouraging, we believe that it would be prudent to broaden the animal experimentation rather than to begin human use. Because no experimental aneurysm models are yet physiological, our results must be applied with caution to human intracranial aneurysms.
Aspergillosis of the neuraxis is a relatively rare entity. It is being encountered with increasing frequency due to the improved care and longevity of immunocompromised patients. Although there are more than 80 cases in the literature, we are aware of only five patients with reported computed tomographic (CT) findings. We report the CT findings of two additional cases.
Explore the source record for details and available documents.
This communication presents our experience with eight patients who were initially evaluated as having normal cerebral computed tomographic (CT) scans. Follow-up scans ranging from 2 to 9 months later showed interval appearance of large contrast enhancing mass producing lesions. All eight of these patients turned out to have glioblastoma multiforme. This phenomenon of "false-negative" CT does not seem to be dependent on the type of equipment used or the age of the patient. Negative CT should not dissuade radiologists and clinicians from believing that a patient with appropriate symptoms and signs does indeed harbor a brain tumor.
Explore the source record for details and available documents.
From November 1976 to September 1979, 46 patients with intracranial arteriovenous malformations or fistulas participated in a clinical study using isobutyl 2-cyanoacrylate (IBCA), with tantalum, for palliative or preoperative occlusion of the blood supply to the abnormalities. Although failure to obtain satisfactory position of a functioning microcatheter precluded deposition of IBCA 10 times, a total of 51 of a possible 62 feeding vessels were occluded with the tantalum-impregnated glue. The technique, results, and complications are discussed in light of the clinical follow-up, which varied from 12 to 48 months.