Prevalence of Traumatic Findings on Routine MRI in a Large Cohort of Professional Fighters.

BACKGROUND AND PURPOSE: Previous studies investigating MR imaging abnormalities among fighters have had small sample sizes. This investigation assessed a large number of fighters using the same conventional sequences on the same scanner. MATERIALS AND METHODS: Conventional 3T MR imaging was used to assess 499 fighters (boxers, mixed martial artists, and martial artists) and 62 controls for nonspecific WM changes, cerebral microhemorrhage, cavum septum pellucidum, and cavum vergae. The lengths of the cavum septum pellucidum and cavum vergae and the ratio of cavum septum pellucidum to the septum pellucidum lengths were assessed. RESULTS: The prevalence of nonspecific WM changes was similar between groups. Fighters had a prevalence of cerebral microhemorrhage (4.2% versus 0% for controls, P = .152). Fighters had a higher prevalence of cavum septum pellucidum versus controls (53.1% versus 17.7%, P < .001) and cavum vergae versus controls (14.4% versus 0%, P < .001). The lengths of the cavum septum pellucidum plus the cavum vergae (P < .001), cavum septum pellucidum (P = .025), and cavum septum pellucidum to the septum pellucidum length ratio (P = .009) were higher in fighters than in controls. The number of fights slightly correlated with cavum septum pellucidum plus cavum vergae length (R = 0.306, P < .001) and cavum septum pellucidum length (R = 0.278, P < .001). When fighters were subdivided into boxers, mixed martial artists, and martial artists, results were similar to those in the whole-group analysis. CONCLUSIONS: This study assessed MR imaging findings in a large cohort demonstrating a significantly increased prevalence of cavum septum pellucidum among fighters. Although cerebral microhemorrhages were higher in fighters than in controls, this finding was not statistically significant, possibly partially due to underpowering of the study.

Magnetic resonance imaging (1.5 tesla) in patients with intractable focal seizures.

Magnetic resonance (MR) (1.5 tesla) studies were performed in ten patients with temporal lobe epilepsy and two with temporofrontal epilepsy. Two patients with temporal lobe epilepsy and one with temporofrontal epilepsy exhibited areas of increased signal intensity on T2-weighted images in the mesiobasal portion of the temporal lobe shown by electroencephalography to be the epileptogenic focus; no analogous abnormalities had been found in these patients on computed tomographic scans. Pathologic studies have not revealed a specific ultrastructural correlate for the MR findings in this group of patients. We found MR to be a useful, noninvasive diagnostic adjunct in the presurgical assessment of some patients with temporal lobe epilepsy. Where abnormalities were found, they corresponded with the epileptogenic focus as defined by electroencephalography.

Magnetic resonance imaging in vascular dementia.

Patients with vascular dementia show distinctive white matter lesions on MRI. We performed MRI on 34 patients with documented ischemic cerebrovascular disease to see whether demented and nondemented patients differ with respect to enlarged CSF spaces or white matter lesions. All eight demented patients had white matter lesions on MRI, just as did many borderline and nondemented patients. Enlargement of central CSF spaces was the only radiographic feature that was seen more commonly in demented than in nondemented patients with ischemic cerebrovascular disease.

Hemorrhage and anticoagulation after nonseptic embolic brain infarction.

Among 54 consecutive patients with acute nonseptic embolic brain infarction, there was CT evidence of hemorrhagic infarction in 1 patient (2%). None had clinical or CT evidence of massive brain hemorrhage even when anticoagulation therapy was used immediately. Seven patients (13%) had recurrent brain emboli, all within 7 days of the initial stroke. None of these patients was adequately anticoagulated at the time of recurrence. Immediate anticoagulation therapy should be employed after nonseptic embolic brain infarction if CT does not show hemorrhage and there is a persistent cardiac source of emboli.

Magnetic resonance angiography of the extracranial carotid arteries and intracranial vessels: a review.

MRI is uniquely suited for evaluation of vascular structures due to its sensitivity to a variety of flow-related phenomena. Recent work has demonstrated that high quality magnetic resonance angiograms (MRA) of the carotid arteries and intracranial vasculature can be achieved by using gradient-echo techniques with short echo times. These MRAs are displayed like conventional arteriograms, but are acquired in a noninvasive fashion with a minimal increase in examination time. We used MRA to visualize 50 of 54 carotid bifurcations tested, with good correlation to the intra-arterial angiograms. We examined the intracranial vasculature in over 40 patients, and demonstrated aneurysms, vascular malformations, and occlusions.

Double-blind study of a new nonionic contrast agent for digital subtraction arteriography.

RATIONALE AND OBJECTIVES: Since the development of the first low-osmolality contrast agent in 1969, a new group of ionic and nonionic compounds have emerged. These new agents have dramatically improved diagnostic imaging by exhibiting significant improvements in safety and technical efficacy over that of high-osmolality agents. This study was designed to compare the safety, tolerance, and technical efficacy of iopromide, a new low-osmolality, nonionic contrast agent, with that of both ioversol and iopamidol for digital subtraction angiography (DSA). METHODS: One hundred fifty patients with conditions requiring intraarterial digital subtraction angiography were randomly assigned to receive 150 mg I/mL iopromide or either 160 mg I/mL ioversol or 128 mg I/mL iopamidol. Cerebral, aortovisceral, and peripheral arteriography was performed. RESULTS: No significant difference was found in safety, tolerance, and technical efficacy between iopromide and ioversol. Iopamidol had significantly less technical efficacy than iopromide, but there were no significant differences in safety or tolerance between these two agents. CONCLUSIONS: All three contrast media (CM) are useful for cerebral DSA. Although these agents were diagnostically adequate for use during aortovisceral and peripheral DSA, none was able to optimally opacify vessels during these studies in the concentrations administered.

Intracranial magnetic resonance imaging.

Magnetic resonance angiography (MRA) is currently being incorporated into the routine MR evaluations of patients with suspected cerebrovascular disease. Currently, MRA serves as a useful adjunct to routine parenchymal spin-echo imaging of the head. Intracranial MRA is predominantly used as a screening test for cerebrovascular disease in situations where the clinical suspicion and/or the patient's physical condition does not warrant a conventional arteriogram. Clinical experience to date suggests that MRA can play a significant role in the evaluation of patients with suspected intracranial aneurysms, arteriovenous fistulae, large vessel occlusive disease, and dural sinus occlusion/thrombosis. MRA has not yet reached the point where it can replace conventional catheter angiography. This is most apparent when trying to evaluate 1) larger vessels which are typically difficult to visualize due to higher order motion terms (eg, carotid siphon); 2) the smaller cortical branches with relatively slow flow that would be necessary to see in patients with suspected vasculitis; and 3) any situation in which dynamic information is important such as with mass lesions or vascular malformations. These limitations must be taken into account when deciding on the appropriate imaging study for an individual patient. Large-scale, well-controlled prospective clinical trials will ultimately determine the role intracranial MRA will play in the evaluation of patients with suspected cerebrovascular disease.

Early patency of the carotid artery after endarterectomy: digital subtraction angiography after two hundred sixty-two operations.

During a 12-month period of study, 265 patients (mean age 65 years) underwent a total of 314 carotid endarterectomies for the management of previous transient cerebral ischemia (39%), prior stroke (10%), or severe asymptomatic carotid stenosis (51%). Five patients (1.6%) died within 30 days of operation, but only three deaths (1%) were related to carotid reconstruction. Six patients (1.9%) experienced postoperative strokes, including 1.6% of those with previous transient ischemia, 9.7% of those with prior strokes (P less than 0.02), and 0.6% of those with asymptomatic carotid stenosis before operation. Digital subtraction angiography (DSA) was performed during the same hospital admission following 262 procedures in a group of 214 patients, including all patients who had postoperative neurologic complications. Seven of these operations were limited to external carotid endarterectomy. The internal carotid artery was entirely normal in 239 (94%) of the remaining 255 DSA studies. The external carotid artery was normal on 238 (93%) of 255 DSA examinations, but was occluded on 12 (4.7%). A focal intimal defect corresponding to the apical arteriotomy suture was found in nine internal carotid arteries (3.6%), but these lesions did not appear to be hemodynamically significant. The internal carotid artery contained over 30% stenosis in two patients (0.8%) and was occluded in five (1.9%). Two of these five patients had neurologic complications, but four others with operative strokes had normal angiograms. Asymptomatic postoperative thrombosis of the internal carotid artery was documented in only three patients (1.2%).

The postoperative lumbar spine: enhanced MR evaluation of the intervertebral disk.

PURPOSE: To document the pattern of enhancement and morphologic changes on MR images that occur in the intervertebral disk and adjacent vertebral bodies after diskectomy and to correlate the presence of intervertebral disk enhancement with the preoperative and postoperative clinical findings. METHODS: Preoperatively, and at 3 months and 6 months after surgery, 94 adults who had first-time surgery for a herniated lumbar intervertebral disk that was associated with radiculopathy, expressed as leg symptoms or signs (with or without lower back pain), were asked to respond to a questionnaire regarding pain, were given serial physical examinations, and were examined with contrast-enhanced MR imaging. The measures of clinical outcome that were evaluated included the straight leg raise sign, radicular pain, and lower back pain. Type of disk herniation, intervertebral disk enhancement, disk space height, and degenerative end-plate changes were also assessed. RESULTS: Of the 94 patients evaluated, 19 (20%) had postoperative intervertebral disk enhancement that was not present on the preoperative study. The pattern of enhancement was remarkably consistent, with 18 of the cases showing linear enhancement within the intervertebral disk, manifested as two thin bands paralleling the end plates. End-plate enhancement was present in 7 (37%) of the 19 patients with disk enhancement. There were no significant associations between disk enhancement and specific clinical symptoms before or after surgery. CONCLUSION: Our group of asymptomatic postoperative patients had anular enhancement (curette site), disk enhancement, and vertebral end-plate enhancement on MR images without evidence of disk space infection. This finding points out the need to understand asymptomatic postoperative changes that are sequelae of surgery and not necessarily indicators of infection.

Tears of the anulus fibrosus: assessment with Gd-DTPA-enhanced MR imaging.

T2-weighted images have been shown to be capable of defining anular tears in vitro as increased signal intensity within the normal low-signal-intensity anulus fibrosus. Since growth of granulation tissue into anular tears has been described as part of the healing process, it seemed likely that gadolinium-DTPA should enhance anular tears as it does scar tissue in other parts of the spine. We retrospectively reviewed spinal MR images from 30 previously unoperated patients and correlated areas of increased signal intensity within the anulus on T2-weighted images with areas of enhancement on T1-weighted images, and to a limited extent, with surgical findings. Eighteen separate areas of anular enhancement were found in 12 patients (six cervical, 12 lumbar). Only five of these enhancing areas showed increased signal intensity on T2-weighted images, four of a type II tear pattern and one of a type III tear pattern. Contrast enhancement within the anulus was in a pattern of type II tear in 14 and type III in four. Histology from an enhancing type II anulus demonstrated vascularized granulation tissue within the avascular anulus, without focal herniation. Anular tears may be imaged in vivo not only with T2-weighted images but also with gadolinium-DTPA-enhanced T1-weighted images by virtue of their vascularized granulation tissue.

MR imaging of the postoperative lumbar spine: assessment with gadopentetate dimeglumine.

This study defines the accuracy of gadopentetate-dimeglumine-enhanced MR imaging in patients with failed back surgery syndrome by comparing the imaging studies with surgical findings in a large patient population. From June 1988 to March 1989, 193 postoperative patients had MR imaging of the lumbar spine both with and without contrast administration. Of this group, 27 had repeat surgery at 31 levels: these patients comprise the study group. Postcontrast MR diagnoses were as follows: scar only (n = 4), disk only (n = 13), scar and disk (n = 9), and no aberrant epidural tissue (n = 5). Surgical diagnoses differed from the MR diagnoses in two patients at two levels. In one patient, disk was diagnosed on MR while osteophyte was present at surgery. In the other patient, scar only was diagnosed by MR but disk and scar were present at surgery. These data, when combined with the authors' previous experience, give pre- and postcontrast MR a 96% accuracy in differentiating scar from disk in 44 patients at 50 reoperated levels. For patients 6 or more weeks past surgery, sagittal and axial T1-weighted MR imaging before and after administration of gadopentetate dimeglumine is an effective method of evaluating the postoperative lumbar spine.

Assessment of extradural degenerative disease with Gd-DTPA-enhanced MR imaging: correlation with surgical and pathologic findings.

To test whether gadolinium-DTPA-enhanced MR would increase the conspicuity of extradural degenerative disease in the previously unoperated patient, we prospectively studied a group of 30 patients with symptoms suggestive of disk disease. Surgical findings and pathologic correlations were used as an objective measure of accuracy. Gadolinium-DTPA increased the confidence of diagnosis at one of eight operated cervical levels (six patients) and changed the diagnosis from extradural degenerative disease to tumor in one patient. The mechanism of enhancement of the epidural space and peridiskal region appears to be related to accumulation of contrast material within the epidural venous plexus, as well as to epidural fibrosis associated with disk disruption and herniation. While the immediate clinical utility of gadolinium-DTPA for morphologic analysis seems limited to difficult cervical spine cases, the presence of enhancement as a marker of epidural fibrosis and attempted healing may prove to be of great importance in studying the natural history and basic pathophysiology of degenerative disk disease.

MR imaging of metastatic GI adenocarcinoma in brain.

PURPOSE: To investigate an observed preferential T2-shortening effect seen in patients with intracerebral metastases from adenocarcinoma of the GI tract. METHODS: Ten patients with intracerebral metastases from adenocarcinoma of the GI tract were evaluated with MR imaging with CT and histopathologic correlation. RESULTS: Nine of 10 patients demonstrated intracranial masses with decreased signal intensity on T2-weighted images. T1-weighted images showed decreased or isointense signal in all cases. Special histologic staining was performed in four of 10 cases, all of which were positive for increased protein (mucin) with no evidence of blood products or calcium. CONCLUSION: We propose that the observed preferential T2-shortening effect is secondary to slowing of rotational and translational proton motion caused by increased protein concentration in the form of mucin.

Intracranial aneurysms: evaluation by MR angiography.

The purpose of this study was to compare the accuracy of a volume gradient-echo MR angiography (MRA) technique with that of intraarterial digital subtraction angiography (IA DSA) in the identification of intracranial aneurysms. The intracranial vasculature was examined in 47 patients by MRA and compared with IA DSA findings in 19 of these patients who had saccular or giant intracranial aneurysms. The remaining 28 patients, in whom no aneurysm was found, served as a control group. MRA was performed with the use of a velocity-compensated gradient-echo sequence (TR = 40-50/TE = 7-15) with a 15 degree flip angle. The sensitivity and specificity were calculated for the evaluation of the cine 3D reconstructions (cine MRA) only, cine MRA + inspection of the individual partitions, and cine MRA + individual partitions + spin-echo studies. Of 21 aneurysms, of which three were missed in two patients, the sensitivity varied from 67% for cine MRA only to 86% for the cine MRA + partitions + spin-echo studies; of the 19 patients, among whom it was assumed that the diagnosis of any one aneurysm in a patient would lead to angiography and detection of additional aneurysms, the sensitivity varied from 73% for the cine MRA only to 95% for the cine MRA + partitions + spin-echo studies. The results of this study suggest that MRA can define the circle of Willis sufficiently to allow detection of intracranial aneurysms as small as 3-4 mm. MRA holds promise as a truly noninvasive screening examination of intracranial vasculature in patients at risk for aneurysms.

Lumbar degenerative disk disease: prospective comparison of conventional T2-weighted spin-echo imaging and T2-weighted rapid acquisition relaxation-enhanced imaging.

PURPOSE: To compare conventional T2-weighted spin-echo imaging with a rapid acquisition relaxation enhanced (RARE) technique in the routine evaluation of lumbar degenerative disk disease. METHODS: Thirty consecutive patients referred for evaluation of the lumbar spine for suspected degenerative disk disease were evaluated with sagittal and axial T1-weighted spin-echo, conventional T2-weighted spin-echo, and T2-weighted RARE "turbo spin-echo" sequences (4000/93/2 (repetition time/echo time/excitations), 192 x 256, echo train length of 8). Conventional T2-weighted and RARE images were evaluated independently by two neuroradiologists for image quality, presence of artifacts, cerebrospinal fluid signal intensity, extradural interface conspicuity, intradural nerve root conspicuity, soft-tissue detail, and signal intensity of normal and degenerated intervertebral disks. RESULTS: Both readers rated the cerebrospinal fluid signal higher, the extradural interface conspicuity higher, and the nerve root detail greater on the turbo spin-echo than on conventional spin-echo images. Neither reader had a significant difference in ranking "normal" or "degenerated" disk signal on the two sequences. Both readers rated soft-tissue detail higher for conventional than for turbo spin-echo. CONCLUSION: RARE sequences can replace conventional T2-weighted spin-echo sagittal studies for degenerative lumbar disk disease.

Gd-DTPA-enhanced 3D MR imaging of cervical degenerative disk disease: initial experience.

PURPOSE: To assess whether a single enhanced T1-weighted gradient echo volume sequence, with the appropriate reformatted images, could be equivalent to a more conventional 2D set of MR sequences for the evaluation of cervical extradural degenerative disk disease (bony canal and foraminal stenosis; disk herniation). MATERIALS AND METHODS: Sixty-one patients evaluated for extradural degenerative disease by MR were imaged with a "standard" MR examination (Sagittal T1-weighted spin echo, axial low flip angle gradient echo), were then given 0.1 mmol/kg Gd-DTPA intravenously, and reimaged with either a 3D FLASH (fast low angle shot), TR 40/TE 7/1 excitation), 40 degree flip angle, acquired as 64, 2-mm sagittal partitions, or a 3D turbo FLASH (MP RAGE-magnetization prepared rapid acquisition gradient echo) (10/4/1), 10 degree flip angle acquired as 128, 2-mm coronal partitions. The volume sequences were reconstructed in the axial plane, and right and left 45 degree oblique coronal planes. The two sets of examinations (standard vs volume) were prospectively interpreted by two neuroradiologists for quality of examination, and location, type, and severity of extradural degenerative disease in a random, blinded, independent fashion. RESULTS: There was no significant difference between the standard examination and the 3D MP RAGE for central extradural disease. The 3D FLASH examination was significantly worse than the standard examination in identification of central extradural disease, with an average of 21 herniations not identified, or underestimated in size. Neither the 3D FLASH, nor the 3D MP RAGE examinations showed any significant improvement compared to the routine 2D examination for the location and severity of foraminal disease. CONCLUSION: If extradural degenerative disk disease is being evaluated, then a single enhanced 3D T1-weighted imaging sequence taking 6 minutes can be equivalent to a routine set of mixed 2D spin echo and low flip angle gradient echo sequences.

Gd-DTPA enhancement of posterior epidural scar: an experimental model.

Because of the tremendous clinical and physiological importance of anterior epidural scar, an easily produced and reproducible model to assess potential pathways for lessening its formation is a necessity. We speculated whether posterior epidural scar (produced by the less complex surgery of laminectomy alone) could be considered equivalent to anterior scar from an imaging standpoint; that is, enhancement following Gd-DTPA irrespective of scar age. Posterior epidural scar in dogs showed the highest degree of enhancement 1 month after surgery, with a rapid decline thereafter out to 4 months postsurgery to a level equivalent to that of paraspinal muscle. Gd-153-DTPA time/activity curves paralleled the Gd-DTPA findings. Light microscopy showed granulation tissue after 1 month, and mature scar with large amounts of collagen 4 months after surgery. Electron microscopy showed tight capillary endothelial junctions. An appropriate model for epidural scar, which has imaging characteristics similar to human anterior scar, necessitates an extensive lumbar laminectomy with anterior epidural dissection. A simple laminectomy, while easily performed, does not provide a physiologically correct time course of enhancement.

The value of fast gradient-echo MR sequences in the evaluation of brain disease.

One-hundred-fifteen patients thought to have intracranial disease were studied with various two-dimensional short repetition time, partial-flip-angle gradient-echo techniques: at 1.0 T, fast low-angle short (FLASH) at 10 degrees and 30 degrees and fast imaging with steady-state precession (FISP) at 60 degrees; at 1.5 T, FLASH 10 degrees, 30 degrees, and 60 degrees, FISP 60 degrees, and contrast-enhanced fast steady state at 60 degrees. These sequences were compared with a T2-weighted spin-echo sequence to determine the relative sensitivities of these techniques in detecting parenchymal lesions. Except for hemorrhagic lesions a substantial number of abnormalities were either not visible or poorly seen on the partial-flip-angle gradient-echo sequences. Minimizing echo time (6-9 msec) to decrease magnetic susceptibility effects did not improve lesion detection. Current usage of two-dimensional gradient-echo techniques for lesion detection is limited, except when calcification or hemorrhage is involved. Their utility may be expanded via the incorporation of three-dimensional techniques and IV contrast agents.

Magnetic resonance. Principles and applications.

Magnetic resonance is a unique, noninvasive imaging modality which allows direct, multiplanar imaging and the possibility of obtaining biochemical information in vivo. Presently, MR appears most applicable to the evaluation of central nervous system abnormalities. The high sensitivity of MR in the evaluation of intracranial pathology suggests that it may eventually replace CT for many suspected diseases, if future investigations are able to improve its specificity. As previously noted, MR may be more diagnostic than other radiologic studies in the evaluation of suspected Chiari malformation, syringomyelia, congenital abnormalities, tumors of the spinal axis, and disc space infection. In the chest, MR appears to be more accurate than CT in the determination of the extent of mediastinal tumor, but at present cannot replace CT because of the lack of experience in imaging parenchymal nodules and benign diseases. MR of the breast is promising, but the size of the lesion may prove to be a limiting factor with magnetic field strengths commonly being utilized. There are inherent difficulties in the evaluation of cardiac disease with MR, but it offers a noninvasive method of investigating congenital heart disease and may provide valuable information in suspected myocardial ischemia and altered cardiac function. MR provides a new method of evaluating the vascular system, both in terms of providing anatomic information on large and medium-sized vessels and flow analysis. In the abdomen, MR appears to be most sensitive in the evaluation of suspected hepatic masses, but as with the brain, greater specificity will be needed to replace CT. At the present time, MR offers no distinct advantage over conventional imaging modalities in the evaluation of pancreatic disease, it maybe more accurate than CT in the staging of renal cell carcinoma. Larger studies are needed to determine the role of MR in the investigation of retroperitoneal adenopathy and adrenal abnormalities. In the pelvis, MR offers the hope of earlier diagnosis of prostatic carcinoma and may replace CT for staging of prostatic carcinoma and transitional cell carcinoma of the bladder. Limited MR experience with benign disease of the female pelvis suggests that it is currently more accurately evaluated with ultrasound. MR appears to be highly sensitive and specific for the diagnosis of avascular necrosis and may provide an early clue in suspected osteomyelitis. Finally, in vivo MR spectroscopy may provide unique metabolic information that was unobtainable prior to the advent of magnetic resonance, if this proves to be technically feasible.

Tissue segmentation for three-dimensional display of human spines.

This paper presents a morphological tissue segmentation technique for the three-dimensional visualization of the human spine. Magnetic resonance images of the human spine were obtained using motion-compensated fast imaging with steady-state free precession (FISP) pulse sequences. The images acquired with these sequences exhibit very high contrast between the bright cerebrospinal fluid (CSF) and the dark spinal cord and nerve roots. This phenomenon has enabled us to apply mathematical morphological processing techniques to extract the spinal nerve roots within the CSF space. The nerve roots were extracted from a set of slices and displayed in a three-dimensional format.