Baseline Survey of the Neuroradiology Work Environment in the United States with Reported Trends in Clinical Work, Nonclinical Work, Perceptions of Trainees, and Burnout Metrics.

BACKGROUND AND PURPOSE: Neuroradiologists have faced continuously increasing clinical workloads. Our aim was to establish and report a baseline survey of the current neuroradiology work environment in the United States and of experiential changes in recent years. MATERIALS AND METHODS: A voluntary survey was sent to practicing and out-of-training members of the American Society of Neuroradiology in the United States. Selected measures included workday volume and length, burnout symptoms, participation in academic and practice-building duties; effects on perceived interpretation quality, communication of abnormal results, and consideration of early retirement or career changes, among others. RESULTS: Four hundred thirty-two respondents across a broad range of experience reported the following: 52.8% (224/424) with teaching responsibilities; 93% (399/430) with workdays extending at least 1 hour past expected, in 45% (193/430) frequently or always; 71.9% (309/430) reading more cases per hour compared to previous years; 79.5% (341/429) sometimes-to-always interpreting cases faster than comfortable for optimal interpretation; and 67.8% (292/431) sometimes or more often with inadequate time to discuss abnormal results. Burnout symptoms ranged between 49% and 75% (211/428 to 322/428) across 4 indices. For academic activities of teaching, mentoring, and research/publications, a mean of 94.3% reported cut-backs during the past few years. For practice-building activities, 92% reported cut-backs, 51.6% (222/429) considered early retirement, and 38.8% (167/429) considered changing careers. CONCLUSIONS: Increasing clinical demands have coincided with destructive effects in the work environment and the ability and desire of neuroradiologists in the United States to perform academic or practice-building duties with a substantial incidence of burnout symptoms. While this survey does not prove causation, the trends and the correlations should be concerning to the leaders of radiology and warrant further monitoring.

Duplex criteria for determination of 50% or greater carotid stenosis.

Recently the North American Symptomatic Carotid Endarterectomy Trial investigators reported a benefit of carotid endarterectomy compared with medical therapy for symptomatic patients with 50% or greater carotid stenosis. This has necessitated the development of screening parameters for diagnosis of 50% or greater carotid stenosis on the basis of the reference standards used in the study by the North American Symptomatic Carotid Endarterectomy Trial. The duplex scans and arteriograms of 110 patients (210 carotid arteries) were reviewed by blinded readers. Duplex measurements of peak systolic velocity and end diastolic velocity were recorded, and the ratio of these velocities in the internal and common carotid arteries was calculated. The criteria determined for detection of 50% or greater stenosis were as follows: peak systolic velocity of the internal carotid artery greater than 170 cm/s (sensitivity, 92%; specificity, 90%; positive predictive value, 92%; negative predictive value, 90%; and accuracy, 91 %); end diastolic velocity of the internal carotid artery greater than 60 cm/s (sensitivity, 92%; specificity, 86%; positive predictive value, 95%; negative predictive value, 79%; and accuracy, 91 %); ratio of peak systolic velocity of the internal carotid artery to peak systolic velocity of the common carotid artery greater than 2 (sensitivity, 93%; specificity, 75%; positive predictive value, 83%; negative predictive value, 89%; and accuracy, 85%); and ratio of end diastolic velocity of the internal carotid artery to end diastolic velocity of the common carotid artery greater than 2.4 (sensitivity, 96%; specificity, 79%; positive predictive value, 88%; negative predictive value, 92%; and accuracy, 89%). It is concluded that 50% or greater carotid artery stenosis can be reliably determined by duplex criteria. The use of receiver operating characteristic curves allows the individualization of duplex criteria to the clinical situation.

Magnetization transfer imaging of traumatic brain injury.

Magnetization transfer imaging (MTI) has been shown to be sensitive for the detection of white matter abnormalities in entities such as multiple sclerosis, progressive multifocal leukoencephalopathy, and wallerian degeneration. Our hypothesis was that MTI would detect traumatic white matter abnormalities (TWMA) and provide information additional to that obtainable with routine spin- and gradient-echo imaging. We hypothesized that the presence of TWMA defined by MTI would correlate with outcome following TBI. Twenty-eight victims of head trauma and 15 normal controls underwent magnetic resonance imaging including MTI. Magnetization transfer ratios (MTR) were calculated for areas of shearing injury and for normal-appearing white matter (NAWM) in locations frequently subject to diffuse axonal injury. Abnormal MTRs were detected in NAWM in eight patients. All eight had persistent neurologic deficits, including cognitive deficits, aphasia, and extremity weakness. Seven of the 28 patients had no abnormal findings on neurologic exam at discharge, transfer, or follow-up. None of these patients had an abnormal MTR in NAWM. In the remaining 13 patients, who had persistent neurologic deficits, no regions of abnormal MTR were detected in NAWM. MTI is a sensitive method for the detection of TWMA. Detection of abnormal MTR in NAWM that is prone to axonal injury may predict a poor patient outcome. The presence of normal MTR in NAWM in these areas does not necessarily confer a good outcome, however.

A case of canine central nervous system cryptococcosis: management with fluconazole.

A three-year-old, female Labrador retriever was presented for acute generalized seizures. Disseminated cryptococcosis with central nervous system (CNS) involvement was diagnosed by serum and cerebrospinal fluid (CSF) fungal titers, histopathological examination, and magnetic resonance imaging (MRI). Fluconazole therapy resulted in prolonged, substantial clinical improvement for a period of one year. This report documents the diagnosis of a case of cryptococcal meningoencephalitis and its management with the new antifungal agent, fluconazole.

Extracranial atherosclerotic carotid artery disease: evaluation of non-breath-hold three-dimensional gadolinium-enhanced MR angiography.

OBJECTIVE: The purpose of this study was to compare the diagnostic information provided by a combination of two-dimensional and three-dimensional (3D) time-of-flight (TOF) techniques with that provided by non-breath-hold 3D spoiled gradient-echo gadolinium-enhanced MR angiography. MATERIALS AND METHODS: Fifty patients suspected of having extracranial atherosclerotic carotid artery disease were examined with all three imaging techniques using a 1.5-T MR imaging system. Three observers independently and retrospectively measured the degree of stenosis according to the North American Symptomatic Carotid Endarterectomy trial criteria. The observers were unaware of the results of other MR imaging pulse sequences and digital subtraction angiography. The standard of reference was established by digital subtraction angiography. Results were evaluated with receiver operating characteristic curve analysis. The degree of interobserver agreement was determined using pairwise kappa statistics. RESULTS: The grading of carotid artery stenosis as measured by the area under the receiver operating characteristic curve was less accurate with non-breath-hold 3D gadolinium-enhanced MR angiography than with TOF imaging. Interobserver variability was greater for non-breath-hold 3D gadolinium-enhanced MR angiography than for TOF techniques. CONCLUSION: Routine evaluation of carotid artery stenosis at the level of the bifurcation using non-breath-hold 3D gadolinium-enhanced MR angiography is less accurate than is TOF imaging and is therefore not recommended. The weakness of this technique may be due to problems in timing the injection of gadolinium and the masking of the carotid bifurcation by the venous jugular system.

Magnetic resonance angiography of the aortic arch.

Duplex ultrasound and magnetic resonance angiographic (MRA) studies are the principal noninvasive methods for evaluation of extracranial occlusive disease in patients at risk for stroke, but each has limited ability to diagnose aortic arch and arch vessel disease. Recent favorable reports of the nonnephrotoxic contrast agent Gadolinium (Gd) being used to enhance MRA images of the abdominal aorta prompted us to examine its utility for the aortic arch vessels. Prospectively, 28 patients with suspected carotid or arch vessel disease were imaged by contrast arteriographic examination and MRA + Gd of the aortic arch within 30 days of each other. One (for contrast arteriograms) or two (for MRA) blinded readers measured stenoses with the contrast arteriograms as the standard. A total of 196 arch vessels containing 58 stenoses and four occlusions (by arteriogram) were examined with each method. Interobserver agreement for interpretation of MRA studies was substantial (kappa = 0.68). MRA detected all anatomic anomalies (e.g., bovine arch). The correlation of MRA with arteriographic scans for arch vessel stenoses > 50% was sensitivity, 73% (readers 1 and 2); specificity, 98% (reader 1), 89% (reader 2); positive predictive value, 73% (reader 1), 89% (reader 2); negative predictive value, 98% (readers 1 and 2); accuracy, 97% (reader 1), 98% (reader 2). MRA + Gd is an accurate new noninvasive imaging method for detection of significant aortic arch disease. In its current state of development, however, it cannot obviate the need for contrast arteriographic examination.

Determination of duplex Doppler ultrasound criteria appropriate to the North American Symptomatic Carotid Endarterectomy Trial.

BACKGROUND AND PURPOSE: The North American Symptomatic Carotid Endarterectomy Trail (NASCET) demonstrated the benefit of carotid endarterectomy for symptomatic patients with > or = 70% carotid stenosis. Screening for detection of significant carotid occlusive disease has relied on duplex Doppler imaging. However, traditional duplex categories (50% to 79%, 80% to 99%) are not directly applicable to NASCET. We sought to evaluate duplex criteria for determination of > or = 70% carotid stenosis. METHODS: Duplex scan and arteriograms of 110 patients (210 carotids), performed within 1 month of each other, were reviewed by blinded readers. Arteriographic stenosis was determined by the NASCET method. Duplex measurements of peak systolic and end-diastolic velocity (PSV, EDV) were recorded, and ratios of velocities in the internal and common carotid arteries (ICA, CCA) were calculated. Receiver-operator characteristic (ROC) curves of sensitivity, specificity, positive and negative predictive values (PPV, NPV), and accuracy were determined. RESULTS: Interobserver agreement for measurement of arteriographic stenosis was "almost perfect" (kappa=0.86). The criteria chosen for detection of > or = 70% stenosis were PSVICA>210 cm/s (sensitivity, 94%; specificity, 77%; PPV, 68% NPV, 96% accuracy, 83%) EDVICA>70 cm/s (sensitivity, 92%; specificity, 60%; PPV, 73%; NPV, 86%; accuracy 77%), PSVica/PSVCCA >3.0 (sensitivity, 91%; specificity, 78%; PPV, 70%; NPV, 94%; accuracy, 83%), and EDVICA/EDVCCA>3.3 (sensitivity, 100%; specificity, 65%; PPV, 65% NPV, 100%; accuracy, 79%). CONCLUSIONS: We conclude that > or = 70% carotid stenosis can be reliably determined by duplex Doppler ultrasound. Individual vascular laboratories must validate their own results.

Determination of sixty percent or greater carotid artery stenosis by duplex Doppler ultrasonography.

PURPOSE: The Asymptomatic Carotid Atherosclerosis Study, demonstrating the benefit of carotid endarterectomy for symptom-free patients with 60% or greater carotid artery stenosis, has given rise to the need for development of screening parameters for detection of these lesions. Traditional duplex categories (50% to 79%, 80% to 99%) are not applicable. We sought to develop duplex criteria for determination of 60% or greater carotid artery stenosis by comparison with arteriography. METHODS: The duplex scans and arteriograms of 110 patients (210 carotid arteries), obtained within 1 month of each other, were reviewed by blinded readers. Arteriographic stenosis was determined by the method of the Asymptomatic Carotid Atherosclerosis Study. Duplex measurements of peak systolic velocity (PSV) and end-diastolic velocity (EDV) were recorded, and ratios of velocities in the internal and common carotid arteries (ICA, CCA) were calculated. Sensitivity, specificity, positive and negative predictive values (PPV, NPV), and accuracy were determined, and receiver-operator characteristic curves were generated. RESULTS: Interobserver agreement for measurement of arteriographic stenosis was "almost perfect" (kappa = 0.86). The criteria determined for detection of 60% or greater stenosis were as follows: PSVICA > 170 cm/sec (sensitivity 98%, specificity 87%, PPV 88%, NPV 98%, accuracy 92%), EDVICA > 40 cm/sec (sensitivity 97%, specificity 52%, PPV 86%, NPV 86%, accuracy 86%), PSVICA/PSVCCA > 2.0 (sensitivity 97%, specificity 73%, PPV 78%, NPV 96%, accuracy 76%), EDVICA/EDVCCA > 2.4 (sensitivity 100%, specificity 80%, PPV 88%, NPV 100%, accuracy 88%). If all of the above criteria were met, 100% accuracy was achieved. CONCLUSION: It is concluded that 60% or greater carotid artery stenosis can be reliably determined by duplex criteria. The use of receiver-operator characteristic curves allows the individualization of duplex criteria appropriate to specific clinical situations of patient screening for lesions (high sensitivity and NPV) or use as a sole preoperative imaging modality (high PPV). Individual vascular laboratories must validate their own results.

Microscopic disease in normal-appearing white matter on conventional MR images in patients with multiple sclerosis: assessment with magnetization-transfer measurements.

PURPOSE: To assess for the presence of microscopic abnormalities in otherwise normal-appearing white matter on T2-weighted images in patients with multiple sclerosis (MS) by using magnetization-transfer (MT) measurements. MATERIALS AND METHODS: Twenty-three patients with MS and nine healthy control subjects underwent magnetic resonance (MR) imaging with a 1.5-T system. MT ratios (MTRs) were measured in 16 areas of normal-appearing white matter identified on conventional T2-weighted images in patients with MS. MTRs in the same white-matter locations in control subjects were determined. The two groups were compared. RESULTS: The mean whole-brain MTR of normal-appearing white matter in patients was 40.13% +/- 1.37 (standard deviation; range, 36.31%-42.09%); in control subjects, 42.93% +/- 0.95 (range, 41.62%-44.50%). The difference was statistically significant (P < or = .001). Except for the internal capsules, the difference in mean MTRs in each sublocation of the brain between patients and control subjects was statistically significant (P < or = .05). CONCLUSION: MT measurements are more sensitive than conventional MR imaging in the detection of abnormalities beyond the resolution of T2-weighted imaging.

Magnetization transfer imaging of periventricular hyperintense white matter in the elderly.

PURPOSE: To characterize with magnetization transfer imaging the pathologic substrate of the nonspecific periventricular hyperintense white matter changes seen on T2-weighted images of elderly patients. METHODS: Twenty-one elderly patients with periventricular hyperintense white matter on T2-weighted MR images and eleven control subjects were studied using MT technique. Magnetization transfer ratios (MTRs) were calculated for the periventricular hyperintense white matter and normal-appearing white matter. These MTRs were correlated with histopathologic changes that have previously been reported as well as with established MTRs for other lesions. RESULTS: The MTRs (mean, 35.2; SD, 1.2) in the periventricular hyperintense white matter are lower than those in the normal white matter of the patient (mean, 40.8; SD, 1.4) and control (mean, 41.3; SD, 1.8) groups. These MTRs are much higher than those of demyelinating lesions but are similar to those of experimental lesions with just edema. CONCLUSION: Because MTR may reflect to some extent histopathologic changes and thus provide more specificity than conventional pulse sequences, the main pathologic substrate accounting for the lower MTR in periventricular hyperintense white matter is probably the increased water content in reactive astrocytes.

MRI of carotid angiopathy after therapeutic radiation.

OBJECTIVE: Our goal was to assess whether significant secondary atherosclerotic changes from radiation can be detected on SE MR of the neck. MATERIALS AND METHODS: Pre- and postradiation MR scans of 16 patients with head and neck malignancies were studied randomly, independently, and blindly by two readers to determine the frequency of narrowing of the carotid arterial lumen and obliteration of the carotid space within the carotid sheath. RESULTS: Interval narrowing of either the common, internal, or external carotid artery lumen was seen in 108 of 192 (56%) of vessels evaluated on postradiation MR scans compared with preradiation studies. The differences in the grades of vessel luminal diameter were statistically significant (p < 0.05 for one reader and p < 0.0001 for the other reader). Among the 16 patients, 3 patients had vessels with a critical degree of stenosis, newly appearing on postradiation scans. Seven of 16 patients had diffuse obliteration of the planes within the carotid space. CONCLUSION: The incidence of accelerated atherosclerosis from therapeutic radiation may be greater than expected in nonirradiated patients. Magnetic resonance scans are an effective, noninvasive method for this type of follow-up.

MR of sarcoidosis in the head and spine: spectrum of manifestations and radiographic response to steroid therapy.

PURPOSE: To evaluate the role of MR in the diagnosis and treatment of patients with neurosarcoidosis. METHODS: The MR studies of 24 patients who satisfied stringent criteria for the diagnosis of sarcoid were retrospectively reviewed. All patients had signs and symptoms referable to the head and/or spine. The majority, 17 patients (71% of the total), were examined at least once with gadolinium enhancement. Fifteen of 24 patients (63%) underwent serial examinations during steroid therapy. RESULTS: A wide spectrum of findings was noted: white matter and periventricular high signal intensity on long-repetition-time/long-echo-time sequences, mimicking multiple sclerosis (11 patients); leptomeningeal enhancement (11 patients); brain parenchymal mass (seven patients)--six demonstrated enhancement, one did not receive contrast; lacrimal gland mass (three patients); hydrocephalus (three patients); enlarged ventricles, apparently atrophic (one patient); periventricular enhancement (three patients); extraaxial mass, mimicking meningioma (two patients); chiasmal enhancement or swelling (one patient); enhancing nerve roots (two patients); enlarged pituitary stalk (two patients); pontine infarct (one patient); and enhancing parenchymal spinal cord mass (three patients). Partial or complete resolution of the radiographic abnormality occurred in 13 of 15 cases (87%), which paralleled clinical improvement. No response was detected in the remaining two. Abnormal enhancement was the finding that was most responsive to steroid therapy, with response seen in nine of 10 patients with leptomeningeal enhancement, in six of six patients with enhancing brain parenchymal masses, in three of three patients with enhancing cord masses, and in all three patients with periventricular enhancement. CONCLUSIONS: 1) MR shows a spectrum of protean central nervous system abnormalities associated with neurosarcoidosis. 2) This high sensitivity for associated abnormalities aids in differentiating central nervous system sarcoid from the many diseases that it can mimic. In particular, enhancement was a useful clue to the diagnosis in 15 of 17 cases in which it was used (88%). 3) MR demonstrates regression of central nervous system abnormalities during steroid therapy, in particular abnormal meningeal, periventricular, and parenchymal enhancement.

Use of magnetisation transfer contrast to improve cerebral 3D MR angiography.

To improve 3D-time of flight (3D-TOF) magnetic resonance angiography, we used magnetisation transfer (MT) to increase the contrast between flowing blood and stationary tissues. With a 1.5 KHz off-resonance radio-frequency MT applied for 16 ms at a maximum power within specific absorption rate (SAR) limits, a 37% decrease in the signal of white matter was obtained, whereas the signal from flowing blood decreased by only 8%. An improvement in maximum intensity projection (MIP) image quality was obtained all MT-3DTOF studies on seven volunteers using progressively more powerful MT pulses. Routine clinical use of MT-3DTOF appears promising and can be achieved at any strength field.

Magnetization transfer: theory and clinical applications in neuroradiology.

Magnetization transfer, a new technique for improving image contrast in magnetic resonance (MR) imaging, is based on application of off-resonance radio-frequency pulses and observing their effects on MR images, as well as measuring the signal intensity with and without application of the pulses (ie, magnetization transfer ratio [MTR]). MTRs can be used to detect changes in the structural status of brain parenchyma that may or may not be visible with standard MR techniques. Use of MTRs may allow subcategorization of multiple sclerosis lesions into those with very low MTR (demyelinated lesions) and slightly decreased MTR (edematous lesions). In cases of wallerian degeneration, use of MTRs appears to allow reliable detection of changes undetectable with MR imaging or even light microscopy. In cases of infection with human immunodeficiency virus, MTRs seem to indicate that the macromolecular structure of white matter remains intact until relatively late in the course of disease. In cases of metastatic disease, MTRs of brain lesions indicate structural changes beyond the extent of the lesions seen on standard MR images. These findings may be due to chronic edema, myelin loss, and perhaps previous undetected tumor. In addition to being a new method of providing contrast, the magnetization transfer technique enables semi-quantitative, reproducible characterization of tissue and pathologic entities, which could substantially improve the specificity of MR imaging.

Dyke Award paper. MR of wallerian degeneration in the feline visual system: characterization by magnetization transfer rate with histopathologic correlation.

PURPOSE: To examine the utility of measuring magnetization transfer ratio for for delineating the dynamic changes of wallerian degeneration which occur after controlled injury in a feline model in which anatomic pathways are well understood. METHODS: Using standard neurosurgical techniques, discrete lesions were made to ablate the visual cortex. Gradient imaging was performed serially at 1.5 T, with and without a saturation pulse to create a magnetization transfer effect. At varying intervals, the animals were killed for histologic analysis. RESULTS: Within the first 2 weeks there is a statistically significant increase in magnetization transfer ratio relative to the control hemisphere within the white matter connections between the lateral geniculate nucleus and the visual cortex at a time when no effects are visually detectable on spin-echo images. Between 16 and 28 days, this reverses to a decrease in magnetization transfer ratio in both the lateral geniculate nucleus itself and the adjacent superolateral white matter. More remote white matter tracts remained stable, without significant change. CONCLUSIONS: Magnetization transfer ratio seems to be more sensitive for early detection of degeneration than conventional spin-echo imaging. Moreover, temporal changes in magnetization transfer ratio seem to correspond well with known histologic phases of wallerian degeneration.

Herpes zoster ophthalmicus with orbital pseudotumor syndrome complicated by optic nerve infarction and cerebral granulomatous angiitis: MR-pathologic correlation.

The authors describe a 41-year-old woman with herpes zoster ophthalmicus and extensive intracranial and orbital involvement as documented by MR and pathologically. MR showed all of the lesions that led to the ophthalmoplegia and pseudotumor syndrome, the periaxial infarct of the distal optic nerve, pontine infarcts, and granulomatous angiitis of the meningeal vessels. MR is useful in both detection and monitoring of the disease.

Deep gray matter hypointensity patterns with aging in healthy adults: MR imaging at 1.5 T.

The authors studied a carefully screened pool of healthy adult volunteers aged 20-80 years, so that a normal brain deep gray matter hypointensity map, as detectable on routine spin-echo magnetic resonance (MR) images, could be formulated. Previous MR imaging studies about brain iron reported findings either in children only or in adults, all of whom had suspected central nervous system disease. The results showed that (a) areas of hypointensity in the red nucleus, substantia nigra, and dentate nucleus were relatively unchanged throughout all age groups; (b) the globus pallidus showed an increased volume of hypointensity in the middle-aged and elderly population compared with that in the young adult; (c) the putamen was hypointense only in the elderly age group; and (d) hypointensity was never seen in the thalamus or caudate nucleus in any subject, regardless of age. In cases in which these patterns are not observed in patients suspected to have central nervous system disease, the presence of such disease should be considered.