Robert D. Zimmerman

Extent of Microstructural White Matter Injury in Postconcussive Syndrome Correlates with Impaired Cognitive Reaction Time: A 3T Diffusion Tensor Imaging Study of Mild Traumatic Brain Injury

BACKGROUND AND PURPOSE: Diffusion tensor imaging (DTI) may be a useful index of microstructural changes implicated in diffuse axonal injury (DAI) linked to persistent postconcussive symptoms, especially in mild traumatic brain injury (TBI), for which conventional MR imaging techniques may lack sensitivity. We hypothesized that for mild TBI, DTI measures of DAI would correlate with impairments in reaction time, whereas the number of focal lesions on conventional 3T MR imaging would not. MATERIALS AND METHODS: Thirty-four adult patients with mild TBI with persistent symptoms were assessed for DAI by quantifying traumatic microhemorrhages detected on a conventional set of T2*-weighted gradient-echo images and by DTI measures of fractional anisotropy (FA) within a set of a priori regions of interest. FA values 2.5 SDs below the region average, based on a group of 26 healthy control adults, were coded as exhibiting DAI. RESULTS: DTI measures revealed several predominant regions of damage including the anterior corona radiata (41% of the patients), uncinate fasciculus (29%), genu of the corpus callosum (21%), inferior longitudinal fasciculus (21%), and cingulum bundle (18%). The number of damaged white matter structures as quantified by DTI was significantly correlated with mean reaction time on a simple cognitive task (r = 0.49, P = .012). In contradistinction, the number of traumatic microhemorrhages was uncorrelated with reaction time (r = −0.08, P = .71). CONCLUSION: Microstructural white matter lesions detected by DTI correlate with persistent cognitive deficits in mild TBI, even in populations in which conventional measures do not. DTI measures may thus contribute additional diagnostic information related to DAI.

A neural basis for the development of inhibitory control

The present study explores the neural basis of the development of inhibitory control by combining functional neuroimaging with a parametric manipulation of a go-nogo paradigm. We demonstrate how the maturation of ventral fronto-striatal circuitry underlies the development of this ability. We used event-related fMRI to examine the effect of interference on neural processes involved in inhibitory control in children and adults. Nogo trials were preceded by either 1, 3 or 5 go trials and then compared to one another. Both children and adults showed an increase in errors with increasing interference. Successful response inhibition was associated with stronger activation of prefrontal and parietal regions for children than for adults. In adults, activation in ventral prefrontal regions increased with increasing interference from go trials. Unlike adults, the circuitry appeared to be maximally activated in children when suppressing a behavioral response regardless of the number of preceding responses. Furthermore, activation in ventral fronto-striatal regions correlated with both age and performance. These findings suggest that immature cognition is more susceptible to interference and this is paralleled by maturational differences in underlying fronto-striatal circuitry.

Comparison of Magnetic Resonance Imaging and Computed Tomography in the Evaluation of Head Injury

Thirty-five patients who had incurred head trauma were studied with computed tomography (CT) and magnetic resonance imaging (MRI). CT was performed using a General Electric 8800 scanner. MRI was conducted with a Technicare Teslacon system using a 5.0 kG (0.5 T) magnetic field. Clinically, patients varied from those with mild concussions without focal neurological signs to those with severe neurological dysfunction including posttraumatic coma. MRI was superior to CT in imaging 23 of 41 extracerebral fluid collections, both in estimating the size of the collections and in diagnosing small collections. MRI was also superior to CT in distinguishing chronic subdural hematomas from hygromas. Further, MRI was superior to CT in visualizing nonhemorrhagic contusion in 15 of 21 lesions. Because of the potential failure of MRI to diagnose acute subarachnoid or acute parenchymal hemorrhage, CT remains the procedure of choice in diagnosing head injury less than 72 hours old.

Ring Blush Associated with Intracerebral Hematoma

Seven cases of ring blush following spontaneous and post-traumatic, subacute and chronic intracerebral hematoma are presented. As such a hematoma ages, a ring blush may be seen following contrast-agent enhancement. Serial CT demonstrates disappearance of the ring blush from two to six months after the first scan. The CT appearance of the ring blush is not specific for hematoma, but its peripheral location and lack of mass effect may be considered suggestive of hematoma with appropriate clinical findings. The characteristic serial changes permit correct diagnosis without surgical intervention in most cases.

Distribution of microstructural damage in the brains of professional boxers: A diffusion MRI study

To investigate and localize cerebral abnormalities in professional boxers with no history of moderate or severe head trauma.

Safety and maximum tolerated dose of superselective intraarterial cerebral infusion of bevacizumab after osmotic blood-brain barrier disruption for recurrent malignant glioma. Clinical article.

OBJECT The authors assessed the safety and maximum tolerated dose of superselective intraarterial cerebral infusion (SIACI) of bevacizumab after osmotic disruption of the blood-brain barrier (BBB) with mannitol in patients with recurrent malignant glioma. METHODS A total of 30 patients with recurrent malignant glioma were included in the current study. RESULTS The authors report no dose-limiting toxicity from a single dose of SIACI of bevacizumab up to 15 mg/kg after osmotic BBB disruption with mannitol. Two groups of patients were studied; those without prior bevacizumab exposure (naïve patients; Group I) and those who had received previous intravenous bevacizumab (exposed patients; Group II). Radiographic changes demonstrated on MR imaging were assessed at 1 month postprocedure. In Group I patients, MR imaging at 1 month showed a median reduction in the area of tumor enhancement of 34.7%, a median reduction in the volume of tumor enhancement of 46.9%, a median MR perfusion (MRP) reduction of 32.14%, and a T2-weighted/FLAIR signal decrease in 9 (47.4%) of 19 patients. In Group II patients, MR imaging at 1 month showed a median reduction in the area of tumor enhancement of 15.2%, a median volume reduction of 8.3%, a median MRP reduction of 25.5%, and a T2-weighted FLAIR decrease in 0 (0%) of 11 patients. CONCLUSIONS The authors conclude that SIACI of mannitol followed by bevacizumab (up to 15 mg/kg) for recurrent malignant glioma is safe and well tolerated. Magnetic resonance imaging shows that SIACI treatment with bevacizumab can lead to reduction in tumor area, volume, perfusion, and T2-weighted/FLAIR signal.

ACR Appropriateness Criteria® on Low Back Pain

Acute low back pain with or without radiculopathy is one of the most common health problems in the United States, with high annual costs of evaluation and treatment, not including lost productivity. Multiple reports show that uncomplicated acute low back pain or radiculopathy is a benign, self-limited condition that does not warrant any imaging studies. Guidelines for recognition of patients with more complicated status can be used to identify those who require further evaluation for suspicion of more serious problems and contribute to appropriate imaging utilization.

Diffusion tensor imaging in the diagnosis of primary lateral sclerosis

To evaluate the utility of MR diffusion tensor imaging in diagnosing primary lateral sclerosis (PLS).

Sparring and Cognitive Function in Professional Boxers

A volunteer group of 42 professional boxers provided information about their careers and training practices and underwent neuropsychological testing. Performance on the neuropsychological tests was not associated with age, boxing record (wins, losses, or total number of bouts), length of career, or history of knockout or technical knockout. However, the amount of sparring the boxers did was inversely associated with their performance on several of the tests. Impairments revealed by the tests were in the areas of attention, concentration, and memory.

Using Quantitative CT Perfusion for Evaluation of Delayed Cerebral Ischemia Following Aneurysmal Subarachnoid Hemorrhage

BACKGROUND AND PURPOSE: DCI is a serious complication following aneurysmal SAH leading to permanent neurologic deficits, infarction, and death. Our aim was to prospectively evaluate the diagnostic accuracy of CTP and to determine a quantitative threshold for DCI in aneurysmal SAH. MATERIALS AND METHODS: Patients with SAH were prospectively enrolled in a protocol approved by the institutional review board. CTP was performed during the typical time period for DCI, between days 6 and 8 following SAH. Quantitative CBF, CBV, and MTT values were obtained by using standard region-of-interest placement sampling of gray matter. The reference standard for DCI is controversial and consisted of clinical and imaging criteria in this study. In a subanalysis of vasospasm, DSA was used as the reference standard. ROC curves determined the diagnostic accuracy by using AUC. Optimal threshold values were calculated by using the patient population utility method. RESULTS: Ninety-seven patients were included; 41% (40/97) had DCI. Overall diagnostic accuracy was 93% for CBF, 88% for MTT, and 72% for CBV. Optimal threshold values were 35 mL/100 g/min (90% sensitivity, 68% specificity) for CBF and 5.5 seconds (73% sensitivity, 79% specificity) for MTT. In the subanalysis (n = 57), 63% (36/57) had vasospasm. Overall diagnostic accuracy was 94% for CBF, 85% for MTT, and 72% for CBV. Optimal threshold values were 36.5 mL/100 g/min (95% sensitivity, 70% specificity) for CBF and 5.4 seconds (78% sensitivity, 70% specificity) for MTT. CONCLUSIONS: CBF and MTT have the highest overall diagnostic accuracy. Threshold values of 35 mL/100 g/min for CBF and 5.5-second MTT are suggested for DCI on the basis of the patient population utility method. Absolute threshold values may not be generalizable due to differences in scanner equipment and postprocessing methods.