Early postoperative MRI and detection of residual adenoma after transsphenoidal pituitary surgery.

OBJECTIVE: Current practice guidelines recommend delayed (≥ 3 months after operation) postoperative MRI after transsphenoidal surgery for pituitary adenomas, although this practice defers obtaining important information, such as the presence of a residual adenoma, that might influence patient management during the perioperative period. In this study, the authors compared detection of residual adenomas by means of early postoperative (EPO) MRI (< 48 hours postsurgery) with both surgeon intraoperative assessment and late postoperative (LPO) MRI at 3 months. METHODS: Adult patients who underwent microscopic transsphenoidal surgery for pituitary adenomas with MRI preoperatively, < 48 hours after the operation, 3 months postoperatively, and yearly for 4 years were included. The presence or absence of residual tumor was assessed intraoperatively by a single surgeon and postoperatively by 2 neuroradiologists blinded to the intraoperative assessment and other postoperative imaging studies. The presence of residual tumor was confirmed by reresection, tumor growth on imaging, or hormonal evidence. Interreader reliability was calculated at each imaging time point. Specificity, sensitivity, positive predictive value, and negative predictive value for EPO and LPO imaging and intraoperative assessment were determined. RESULTS: In total, 102 consecutive patients who underwent microscopic transsphenoidal resection of a pituitary adenoma were included. Eighteen patients (18%) had confirmed residual tumors (12 confirmed by tumor growth, 5 by surgery, and 1 by biochemical evidence of persistent disease). Interreader reliability for detecting residual tumor on EPO MRI was almost perfect (κ = 0.88) and significantly higher than that for LPO MRI (κ = 0.69, p = 0.03). EPO MRI was highly specific for residual tumor (98%), a finding similar to that for intraoperative assessment (99%, p = 0.60) and significantly higher than that for LPO MRI (81%, p < 0.001). Notably, EPO MRI was significantly more sensitive for residual tumor (100%) than both intraoperative assessment (78%, p = 0.04) and LPO MRI (78%, p = 0.04). EPO MRI had a 100% negative predictive value and was used to find 4 residual tumors that were not identified intraoperatively. Residual tumors found on EPO MRI allowed for reresection during the same hospitalization for 3 patients. CONCLUSIONS: EPO MRI after transsphenoidal pituitary surgery can be reliably interpreted and has greater sensitivity for detecting residual tumor than intraoperative assessment and LPO MRI. This result challenges current guidelines stating that delayed postoperative imaging is preferable to early imaging. Pituitary surgeons should consider performing EPO MRI either in addition to or instead of delayed imaging.

Significance of degree of neurovascular compression in surgery for trigeminal neuralgia.

OBJECTIVE: The aim of this study was to identify preoperative imaging predictors of surgical success in patients with classic trigeminal neuralgia (cTN) undergoing microvascular decompression (MVD) via retrospective multivariate regression analysis. METHODS: All included patients met criteria for cTN and underwent preoperative MRI prior to MVD. MR images were blindly graded regarding the presence and severity (i.e., mild or severe) of neurovascular compression (NVC). All patients were contacted by telephone to determine their postoperative pain status. RESULTS: A total of 79 patients were included in this study. Sixty-two patients (78.5%) were pain-free without medication following MVD. The following findings were more commonly observed with the symptomatic nerve when compared to the contralateral asymptomatic nerve: NVC (any form), arterial compression alone, NVC along the proximal trigeminal nerve, and severe NVC (p values < 0.0001). The only imaging variable that was a statistically significant predictor of being pain-free without medication following MVD was severe NVC. Patients with severe NVC were 6.36 times more likely to be pain-free following MVD compared to those without severe NVC (p = 0.007). CONCLUSIONS: In patients with cTN undergoing MVD, severe NVC on preoperative MRI is a strong predictor of an excellent surgical outcome.

Contrast-Induced Acute Kidney Injury: Pathophysiology, Manifestations, Prevention, and Management.

Contrast-induced acute kidney injury is a phenomenon that has been extensively studied throughout the years. There is a large volume of literature documenting this risk, and most radiology departments and radiologists use this information when making decisions regarding contrast administration. A review of the current information on the topic of contrast-induced acute kidney injury is necessary to ensure that the risks of intravenous contrast are properly weighed against the benefits of a contrast-enhanced computed tomography scan.

PET/CT for Head and Neck Squamous Cell Carcinoma: Should We Routinely Include the Head and Abdomen?

OBJECTIVE: The purpose of our study was to determine the diagnostic and therapeutic yield of the head and abdomen portions of PET/CT scans of patients with head and neck squamous cell cancer (HNSCC) to determine whether these areas should be routinely included with PET/CT of the neck and chest. MATERIALS AND METHODS: Patients with pathologically proven HNSCC who underwent full-body PET/CT were evaluated for metastases to the head, chest, and abdomen. Medical records were reviewed to determine whether the head and abdominal findings changed the clinical management, beyond the findings in the neck and chest. RESULTS: Five hundred ninety-eight patients who underwent 1625 PET/CT scans were included. All studies included the head, neck, and chest. For 542 of 598 patients (91%), the PET/CT scans included the abdomen. Two of 598 patients (0.3%) had distant calvarial metastases. Neither of the calvarial metastases changed patient management. Twelve of 542 patients (2.2%) had abdominal metastases. For 10 of 542 patients (1.8%), the abdominal findings changed patient management. Thoracic metastases were found in 82 of 598 patients (13.7%). The total rate of distant metastases to the head and abdomen in patients with thoracic metastatic disease was 12.2% (10/82), whereas in patients without thoracic metastases, it was 0.8% (4/460). CONCLUSION: Routine extension of PET/CT scans to include the head and abdomen in patients with HNSCC is not indicated. For patients without evidence of thoracic metastases, routine PET/CT examinations should include the neck and chest only.

Reproducibility and Bias in Healthy Brain Segmentation: Comparison of Two Popular Neuroimaging Platforms.

We evaluated and compared the performance of two popular neuroimaging processing platforms: Statistical Parametric Mapping (SPM) and FMRIB Software Library (FSL). We focused on comparing brain segmentations using Kirby21, a magnetic resonance imaging (MRI) replication study with 21 subjects and two scans per subject conducted only a few hours apart. We tested within- and between-platform segmentation reliability both at the whole brain and in 10 regions of interest (ROIs). For a range of fixed probability thresholds we found no differences between-scans within-platform, but large differences between-platforms. We have also found very large differences between- and within-platforms when probability thresholds were changed. A randomized blinded reader study indicated that: (1) SPM and FSL performed well in terms of gray matter segmentation; (2) SPM and FSL performed poorly in terms of white matter segmentation; and (3) FSL slightly outperformed SPM in terms of CSF segmentation. We also found that tissue class probability thresholds can have profound effects on segmentation results. We conclude that the reproducibility of neuroimaging studies depends on the neuroimaging software-processing platform and tissue probability thresholds. Our results suggest that probability thresholds may not be comparable across platforms and consistency of results may be improved by estimating a probability threshold correspondence function between SPM and FSL.

White Matter Injuries in Mild Traumatic Brain Injury and Posttraumatic Migraines: Diffusion Entropy Analysis.

Purpose To determine the performance of Shannon entropy (SE) as a diagnostic tool in patients with mild traumatic brain injury (mTBI) with posttraumatic migraines (PTMs) and those without PTMs on the basis of analysis of fractional anisotropy (FA) maps. Materials and Methods The institutional review board approved this retrospective study, with waiver of informed consent. FA maps were obtained and neurocognitive testing was performed in 74 patients with mTBI (57 with PTM, 17 without PTM). FA maps were obtained in 22 healthy control subjects and in 20 control patients with migraine headaches. Mean FA and SE were extracted from total brain FA histograms and were compared between patients with mTBI and control subjects and between patients with and those without PTM. Mean FA and SE were correlated with clinical variables and were used to determine the areas under the receiver operating characteristic curve (AUCs) and likelihood ratios for mTBI and development of PTM. Results Patients with mTBI had significantly lower SE (P < .001) and trended toward lower mean FA (P = .07) compared with control subjects. SE inversely correlated with time to recovery (TTR) (r = -0.272, P = .02). Patients with mTBI with PTM had significantly lower SE (P < .001) but not mean FA (P = .15) than did other patients with mTBI. SE provided better discrimination between patients with mTBI and control subjects than mean FA (AUC = 0.92; P = .01), as well as better discrimination between patients with mTBI with PTM and those without PTM (AUC = 0.85; P < .001). SE of less than 0.751 resulted in a 16.1 increased likelihood of having experienced mTBI and a 3.2 increased likelihood of developing PTM. Conclusion SE more accurately reveals mTBI than mean FA, more accurately reveals those patients with mTBI who develop PTM, and inversely correlates with TTR. (©) RSNA, 2016.

Evaluation of White Matter Injury Patterns Underlying Neuropsychiatric Symptoms after Mild Traumatic Brain Injury.

PURPOSE: To determine if a central axonal injury underlies neuropsychiatric symptoms after mild traumatic brain injury (mTBI) by using tract-based spatial statistics analysis of diffusion-tensor images. MATERIALS AND METHODS: The institutional review board approved this study, with waiver of informed consent. Diffusion-tensor imaging and serial neurocognitive testing with the Immediate Post-Concussion Assessment and Cognitive Testing evaluation were performed in 45 patients with mTBI (38 with irritability, 32 with depression, and 18 with anxiety). Control subjects consisted of 29 patients with mTBI without neuropsychiatric symptoms. Fractional anisotropy and diffusivity maps were analyzed by using tract-based spatial statistics with a multivariate general linear model. Diffusion-tensor imaging findings were correlated with symptom severity, neurocognitive test scores, and time to recovery with the Pearson correlation coefficient. RESULTS: Compared with control subjects, patients with mTBI and depression had decreased fractional anisotropy in the superior longitudinal fasciculus (P = .006), white matter around the nucleus accumbens (P = .03), and anterior limb of the internal capsule (P = .02). Patients with anxiety had diminished fractional anisotropy in the vermis (P = .04). No regions of significantly decreased fractional anisotropy were seen in patients with irritability relative to control subjects. Injury in the region of the nucleus accumbens inversely correlated with recovery time in patients with depression (r = -0.480, P = .005). CONCLUSION: Unique white matter injury patterns were seen for two major posttraumatic neuropsychiatric symptoms. Injury to the cerebellar vermis in patients with mTBI and anxiety may indicate underlying dysfunction in primitive fear conditioning circuits in the cerebellum. Involvement of the nucleus accumbens in depression after mTBI may suggest an underlying dysfunctional reward circuit that affects the prognosis in these patients.

Assessment of rates of acute adverse reactions to gadobenate dimeglumine: review of more than 130,000 administrations in 7.5 years.

OBJECTIVE: The purpose of this study was to determine the incidence of adverse events associated with gadobenate dimeglumine over 7.5 years in a major hospital system consisting of both academic and community hospitals. SUBJECTS AND METHODS: As part of a regular and continuous prospective quality assurance project, MRI technologists contemporaneously recorded all gadolinium-based contrast administrations and any associated adverse reactions, including type of reaction and treatment rendered, between August 1, 2005, and March 14, 2013. Weekly data review was performed by the director of MRI services, who evaluated data both by individual site and by comparison among the participating hospitals and sites within the hospital system. Comparison between reaction rates at different sites was performed with a chi-square test. RESULTS: Over 7.5 years, 132,252 doses of gadobenate dimeglumine were administered, and 236 reactions were recorded (0.18% of contrast-enhanced examinations). Of these, 133 (56.4% of all adverse reactions) required treatment and 12 (5.1%) qualified as serious. Reaction rates were significantly different between academic (0.23%) and community (0.07%) hospitals (p<0.001). Reaction rates were higher in the initial years of the study, tapering to a lower baseline rate, which was maintained over more than 5 years. The findings were consistent with the Weber and Lalli effects reported in the literature on other pharmaceutical agents. CONCLUSION: Rates of adverse reactions to gadobenate dimeglumine recorded over 7.5 years were comparable to those reported for other gadolinium-based contrast agents examined over smaller time ranges and populations. The findings reinforce the relatively robust safety profile of this agent.

A multi-disciplinary model of risk factors for fatal outcome in posterior reversible encephalopathy syndrome.

PURPOSE: To evaluate the relative impact of clinical data, imaging findings, and CSF laboratory values on clinical outcome in patients with posterior reversible encephalopathy syndrome (PRES). METHODS: 47 patients with PRES who underwent a lumbar puncture were retrospectively evaluated. Fatal outcome was defined as death directly ascribed to PRES toxicity. Univariate and multivariate analyses were used to evaluate the association between fatal outcome and clinical factors (demographics, PRES etiology), imaging findings (signal abnormality severity, atypical distribution, restricted diffusion, hemorrhage, enhancement, angiographic abnormalities), and lumbar puncture results (appearance, cell count, glucose, protein, culture results). RESULTS: Nine patients (19.1%) had a fatal outcome. Odds of a fatal outcome increased nearly 5-fold with hemorrhage on imaging (Adjusted Odds Ratio (AOR) 4.8, 95% CI 3.8-6.0, p=0.03) and nearly doubled with low CSF glucose (AOR 1.9, 95% CI 1.5-2.5, p=0.02). Hypertensive encephalopathy as an etiology was associated with a fatal outcome (AOR 1.6, 95% CI 1.3-2.9, p=0.02), while toxemia of pregnancy was protective, with a 75% decreased risk (AOR 0.25, 95% CI 0.15-0.43, p=0.02). CONCLUSION: Clinical, imaging, and CSF laboratory findings all influence outcome in PRES, with a low CSF glucose, hypertensive encephalopathy, and imaging findings of hemorrhage associated with increased risk of fatal outcome.

Value of prominent flow voids without cord edema in the detection of spinal arteriovenous fistulae.

PURPOSE: To determine the prevalence of spinal dural arteriovenous fistulae (SDAVF) in patients presenting with prominent vascular flow voids on imaging without other imaging findings suggestive of SDAVF. METHODS: We retrospectively identified patients from January 1, 2005 to March 1, 2012 who underwent spinal angiography for suspected SDAVF with prominent vascular flow voids on prior imaging. We excluded patients with other major spinal pathology or other imaging findings of SDAVF including cord hyperintensity, enhancement, or expansion. We calculated the proportion of patients with positive findings for SDAVF on angiography and evaluated the prevalence of SDAVF for this finding alone and in correlation with clinical findings. RESULTS: 18 patients underwent spinal angiography for prominent flow voids on imaging without other spinal pathology or imaging findings of SDAVF. Three had a SDAVF detected on angiography. The prevalence of SDAVF in this population was low, only 17% (95% CI 6-39%). All of the patients with positive angiography findings had myelopathy, increasing the prevalence to 100% if the additional clinical finding of myelopathy was present. CONCLUSIONS: Prominent flow voids without other imaging findings suggestive of SDAVF is poorly predictive of the presence of a SDAVF, unless myelopathy is present clinically.

Neurodegenerative changes after mild traumatic brain injury.

A link between mild traumatic brain injury (mTBI) and neurodegenerative diseases, specifically Alzheimer's disease and chronic traumatic encephalopathy (CTE), has long been suspected. Shared clinical symptomology - most notably the prominent role of central auditory dysfunction and sleep-wake disturbances in both disease states - and similar findings on postmortem pathological examination has further reinforced suspected commonality between these seemingly disparate entities. However, conventional imaging techniques, including computed tomography and anatomic magnetic resonance, are unable to detect the symptomatic injuries in mTBI patients and therefore detection of neurodegenerative changes in vivo has previously not been reported. Recent research using diffusion tensor imaging, a novel imaging technique, and focused on patient-reported symptoms has for the first time demonstrated imaging findings in mTBI patients in vivo that are strikingly similar to Alzheimer's dementia and CTE. Moving forward, research will focus on identifying what renders certain patients with mTBI susceptible to developing full-fledged Alzheimer's disease and CTE later in life.

Sex differences in white matter abnormalities after mild traumatic brain injury: localization and correlation with outcome.

PURPOSE: To evaluate sex differences in diffusion-tensor imaging (DTI) white matter abnormalities after mild traumatic brain injury (mTBI) using tract-based spatial statistics (TBSS) and to compare associated clinical outcomes. MATERIALS AND METHODS: The institutional review board approved this study, with waiver of informed consent. DTI in 69 patients with mTBI (47 male and 22 female patients) and 21 control subjects (10 male and 11 female subjects) with normal conventional magnetic resonance (MR) images were retrospectively reviewed. Fractional anisotropy (FA) maps were generated as a measure of white matter integrity. Patients with mTBI underwent serial neurocognitive testing with Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT). Correlation between sex, white matter FA values, ImPACT scores, and time to symptom resolution (TSR) were analyzed with multivariate analysis and TBSS. RESULTS: No significant difference in age was seen between males and females (control subjects, P = .3; patients with mTBI, P = .34). No significant difference was seen in initial ImPACT symptom scores (P = .33) between male and female patients with mTBI. Male patients with mTBI had significantly decreased FA values in the uncinate fasciculus (UF) bilaterally (mean FA, 0.425; 95% confidence interval: 0.375, 0.476) compared with female patients with mTBI and control subjects (P < .05), with a significantly longer TSR (P = .04). Multivariate analysis showed sex and UF FA values independently correlated with TSR longer than 3 months (adjusted odds ratios, 2.27 and 2.38; P = .04 and P < .001, respectively), but initial symptom severity did not (adjusted odds ratio, 1.15; P = .35). CONCLUSION: Relative sparing of the UF is seen in female compared with male patients after mTBI, with sex and UF FA values as stronger predictors of TSR than initial symptom severity.

Detection of central white matter injury underlying vestibulopathy after mild traumatic brain injury.

PURPOSE: To determine if central axonal injury underlies vestibulopathy and ocular convergence insufficiency after mild traumatic brain injury (TBI) by using tract-based spatial statistics (TBSS) analysis of diffusion-tensor imaging (DTI). MATERIALS AND METHODS: The institutional review board approved this study, and the requirement to obtain informed consent was waived. Diffusion-tensor images were retrospectively reviewed in 30 patients with mild TBI and vestibular symptoms and 25 patients with mild TBI and ocular convergence insufficiency. Control subjects consisted of 39 patients with mild TBI without vestibular abnormalities and 17 patients with mild TBI and normal ocular convergence. Fractional anisotropy (FA) maps were generated as a measure of white matter integrity and were analyzed with TBSS regression analysis by using a general linear model. DTI abnormalities were correlated with symptom severity, neurocognitive test scores, and time to recovery with the Pearson correlation coefficient. RESULTS: Compared with control subjects, patients with mild TBI and vestibular symptoms had decreased neurocognitive test scores (P < .05) and FA values in the cerebellum and fusiform gyri (P < .05). Patients with ocular convergence insufficiency had diminished neurocognitive test scores (P < .05) and FA values in the right anterior thalamic radiation and right geniculate nucleus optic tracts (P < .0001). Cerebellar injury showed an inverse correlation with recovery time (R = -0.410, P = .02). Anterior thalamic radiation injury showed correlation with decreased processing speed (R = 0.402, P < .05). CONCLUSION: DTI findings in patients with mild TBI and vestibulopathy support the hypothesis that posttraumatic vestibulopathy has a central axonal injury component. Peripheral vestibular structures were not assessed, and a superimposed peripheral contribution may exist. DTI evaluation of central vestibular structures may provide a diagnostic imaging tool in these patients and a quantitative biomarker to aid in prognosis.

Angioglioma misdiagnosed as encephalomalacia on magnetic resonance imaging for over a decade.

We report a case of intractable seizures secondary to an angioglioma that was misdiagnosed as post-traumatic encephalomalacia for over a decade, with a discussion of the radiological findings and a review of the literature.

Evaluation of tentorial length and angle in sleep-wake disturbances after mild traumatic brain injury.

OBJECTIVE: The purpose of this study was to determine if there is an association between tentorial length and angle and sleep-wake disturbances in patients with mild traumatic brain injury (TBI). MATERIALS AND METHODS: MRI examinations of the brain of 34 consecutive patients with mild TBI with sleep-wake disturbance and 30 patients with mild TBI without sleep-wake disturbance were retrospectively reviewed. The length of the tentorium on a sagittal T1-weighted image (tentorial length) and the angle formed between the tentorium and a line through the foramen magnum (tentorial angle) were measured. Results were correlated with both neuropsychologic testing and any sleep-wake disturbance. RESULTS: No significant difference existed between patients with and without sleep-wake disturbances in terms of age (p=0.44), sex (p=0.13), Immediate Post-Concussion Assessment Cognitive Test total symptom score (p=0.10), verbal memory score (p=0.32), visual memory score (p=0.31), processing speed (p=0.15), or reaction time (p=0.84). Tentorial length in patients with mild TBI with sleep-wake disturbances was significantly longer than patients with mild TBI without sleep-wake disturbances (p<0.01), and tentorial angle was significantly smaller (p<0.01). Tentorial angle was inversely correlated with length of time to recovery (p=0.002), and tentorial length was directly correlated with length of time to recovery (p<0.001). CONCLUSION: Among patients with mild TBI with similar cognitive function and symptom severity, those with sleep-wake disturbances have significantly longer tentorial length with a flatter angle than do patients with mild TBI without sleep symptoms, with length of time to recovery being directly correlated with tentorial length and indirectly correlated with tentorial angle. Direct impact between the tentorium and the pineal gland during mild TBI may lead to pineal gland injury, disruption of melatonin homeostasis, and sleep-wake disturbances.

Comparison of simulated cone beam computed tomography to conventional helical computed tomography for imaging of rhinosinusitis.

OBJECTIVES/HYPOTHESIS: Cone beam computed tomography (CBCT) has emerged as a low radiation dose alternative to traditional computed tomography (CT) to evaluate the paranasal sinuses. The purpose of our study was to determine how often clinically important findings would be missed if CBCT was used routinely for sinus imaging. STUDY DESIGN: Retrospective review. METHODS: We evaluated all maxillofacial CT scans performed for sinusitis over a 1-year period. The original multidetector CT (MDCT) images were reviewed retrospectively. A theoretical CBCT was then created from the original study utilizing only the bone algorithm images and separately reviewed. We calculated the proportion of abnormal findings that were identified on the MDCT but would have been missed by the theoretical CBCT, and reviewed the medical record to determine which potentially missed findings would have changed management. Radiation dose from the MDCT scanners was calculated and compared to published dose estimates for the paranasal sinuses on CBCT. RESULTS: Maxillofacial CTs from 361 consecutive patients were included, of which 12 (3.3%) demonstrated findings that would have been missed on the theoretical CBCT. Of those, four (1.1%) would have resulted in a change in management. Effective radiation dose for our scanners ranged from 0.67 mSv to 2.15 mSv, compared to a published estimated dose of 0.2 mSV for CBCT. CONCLUSIONS: In the majority of patients undergoing simulated CBCT for evaluation of sinusitis, incidental findings of soft-tissue disease were rare. With appropriate selection of patients, CBCT can offer substantial radiation dose reduction and may provide a viable alternative to standard MDCT sinus imaging protocols.

Incidental findings of CSF leakage in patients without spontaneous intracranial hypotension and development of post-dural puncture headache.

OBJECTIVES: To determine if nerve root sleeve diverticula or CSF leakage correlate with post-dural puncture headache (PDPH). METHODS: A total of 781 lumbar and 408 cervical post-myelogram CTs were reviewed using a total diverticulum and leakage (TDL) score: 1, nerve root sleeve diverticulum not beyond the lateral vertebral body; 2, diverticulum beyond the lateral vertebral body; 3, periradicular contrast; 4, epidural contrast medium collection. Two scores at each level (left, right) were added for a total score. Results were correlated with post-procedure follow-up. RESULTS: PDPH occurred in 22 (2.8 %) lumbar and 15 (3.7 %) cervical patients. Iodine concentration was not significantly different in lumbar (P = 0.14) or cervical (P = 0.85) patients with or without PDPH. Total scores correlated with PDPH after lumbar (P < 0.0001) and cervical (P < 0.0001) myelography. PDPH patients were younger (P = 0.002 lumbar, P = 0.0001 cervical) and more were female (P = 0.039 lumbar, P = 0.045 cervical). Using multiple regression, a lumbar epidural contrast collection or cervical diverticulum extending beyond the lateral vertebral body correlated with PDPH (P < 0.0001 and P = 0.03, respectively). CONCLUSIONS: PDPH correlates with a higher TDL score. Lumbar epidural contrast medium collections and cervical diverticula extending beyond the lateral vertebral body margin are associated with PDPH. KEY POINTS: • Elongated cervical nerve root sleeve diverticula are associated with post-dural puncture headaches. • Lumbar epidural contrast medium collections are associated with post-dural puncture headaches. • This information may help assess the risk of post-dural puncture headache.

Cervical spinal cord infarction after cervical spine decompressive surgery.

OBJECTIVE: To report five patients who underwent cervical decompressive surgeries and developed persistent postoperative neurologic deficits compatible with spinal cord infarctions and evaluate causes for these rare complications. METHODS: The clinical courses and imaging studies of five patients were retrospectively analyzed. Imaging findings, types of surgeries, vascular compromise or risk factors, hypotensive episodes, intraoperative somatosensory evoked potentials, concomitant brain infarctions, and clinical degree and radiographic extent of spinal cord infarction were studied. The presence of spinal cord infarction was determined by clinical course and imaging evaluation. RESULTS: All five patients had antecedent cervical cord region vascular compromise or generalized vascular risk factors. Four patients developed hypotensive episodes, two intraoperatively and two postoperatively. None of the four patients with hypotensive episodes had imaging or clinical evidence of concomitant brain infarctions. CONCLUSIONS: Neuroimaging evaluation of spinal cord infarction after decompressive surgery is done to exclude spinal cord compression, to ensure adequate surgical decompression, and to confirm infarction by imaging. Antecedent, unrecognized preoperative vascular compromise may be a significant contributor to spinal cord infarction by itself or in combination with hypotension.

Evaluation of a limited three-slice head CT protocol for monitoring patients with ventriculoperitoneal shunts.

OBJECTIVE: Patients with a ventriculoperitoneal shunt for the management of hydrocephalus often undergo multiple head CT examinations for assessment of shunt malfunction. The purpose of this study was to evaluate whether a limited three-slice CT protocol would consistently provide adequate information for the diagnosis of shunt malfunction with a decrease in effective dose. MATERIALS AND METHODS: The study group included 231 unenhanced head CT examinations performed on 128 patients with shunts for hydrocephalus. The original contiguous CT images were reviewed retrospectively. A theoretic limited three-slice study was then created from the original complete CT study and separately reviewed. This limited three-slice study was created by using the lateral topographic image to select three axial locations as follows: midpoint between foramen magnum and vertex, top of the mastoid air cells, and orbital roof. The limited study was graded for parameters of image adequacy with the original full protocol study as the reference standard. RESULTS: Twenty-four of the 231 (10.4%) full studies had findings consistent with shunt failure; all 231 studies would have been correctly categorized with the limited three-slice protocol. The sensitivity of three-slice CT for identifying the ventricular system was 91.6% and for identifying the catheter tip, 93.5%. Limited-slice CT examination would have resulted in greater than 90% mean dose reduction in both adult and pediatric populations. CONCLUSION: Unenhanced head CT with a limited-slice protocol provides adequate diagnostic information for the diagnosis of shunt malfunction with a greater than 90% reduction in effective dose.

Symptomatic white matter changes in mild traumatic brain injury resemble pathologic features of early Alzheimer dementia.

PURPOSE: To evaluate white matter integrity in patients with mild traumatic brain injury (TBI) who did not have morphologic abnormalities at conventional magnetic resonance (MR) imaging with diffusion-tensor imaging to determine any relationship between patterns of white matter injury and severity of postconcussion symptoms. MATERIALS AND METHODS: The institutional review board approved this study, with waiver of informed consent. Diffusion-tensor images from 64 consecutive patients with mild TBI obtained with conventional MR imaging were evaluated retrospectively. Fractional anisotropy (FA) maps were generated as a measure of white matter integrity. All patients underwent a neurocognitive evaluation. Correlations between skeletonized FA values in white matter, total concussion symptom score, and findings of sleep and wake disturbances were analyzed with regression analysis that used tract-based spatial statistics. RESULTS: Total concussion symptom scores varied from 2 to 97 (mean ± standard deviation, 32.7 ± 24.4), with 34 patients demonstrating sleep and wake disturbances. Tract-based spatial statistics showed a significant correlation between high total concussion symptom score and reduced FA at the gray matter-white matter junction (P < .05), most prominently in the auditory cortex (P < .05). FA in the parahippocampal gyri was significantly decreased in patients with sleep and wake disturbances relative to patients without such disturbances (0.26 and 0.37, respectively; P < .05). CONCLUSION: The distribution of white matter abnormalities in patients with symptomatic mild TBI is strikingly similar to the distribution of pathologic abnormalities in patients with early Alzheimer dementia, a finding that may help direct research strategies.