Corticospinal tract atrophy and motor fMRI predict motor preservation after functional cerebral hemispherectomy.

OBJECTIVE The potential loss of motor function after cerebral hemispherectomy is a common cause of anguish for patients, their families, and their physicians. The deficits these patients face are individually unique, but as a whole they provide a framework to understand the mechanisms underlying cortical reorganization of motor function. This study investigated whether preoperative functional MRI (fMRI) and diffusion tensor imaging (DTI) could predict the postoperative preservation of hand motor function. METHODS Thirteen independent reviewers analyzed sensorimotor fMRI and colored fractional anisotropy (CoFA)-DTI maps in 25 patients undergoing functional hemispherectomy for treatment of intractable seizures. Pre- and postoperative gross hand motor function were categorized and correlated with fMRI and DTI findings, specifically, abnormally located motor activation on fMRI and corticospinal tract atrophy on DTI. RESULTS Normal sensorimotor cortical activation on preoperative fMRI was significantly associated with severe decline in postoperative motor function, demonstrating 92.9% sensitivity (95% CI 0.661-0.998) and 100% specificity (95% CI 0.715-1.00). Bilaterally robust, symmetric corticospinal tracts on CoFA-DTI maps were significantly associated with severe postoperative motor decline, demonstrating 85.7% sensitivity (95% CI 0.572-0.982) and 100% specificity (95% CI 0.715-1.00). Interpreting the fMR images, the reviewers achieved a Fleiss' kappa coefficient (κ) for interrater agreement of κ = 0.69, indicating good agreement (p < 0.01). When interpreting the CoFA-DTI maps, the reviewers achieved κ = 0.64, again indicating good agreement (p < 0.01). CONCLUSIONS Functional hemispherectomy offers a high potential for seizure freedom without debilitating functional deficits in certain instances. Patients likely to retain preoperative motor function can be identified prior to hemispherectomy, where fMRI or DTI suggests that cortical reorganization of motor function has occurred prior to the operation.

MR Diffusion Tractography to Identify and Characterize Microstructural White Matter Tract Changes in Systemic Lupus Erythematosus Patients.

PURPOSE: Systemic lupus erythematosus (SLE) is a predominantly female autoimmune disease that can affect the central nervous system. Neuropsychiatric symptoms are found in 25-70% of SLE patients. Using diffusion tensor imaging, various studies have reported changes in white matter integrity in SLE patients with neuropsychiatric symptoms (NPSLE patients). The purpose of this study was to investigate if changes can be detected in the individual white matter tracts in SLE patients regardless if neuropsychiatric symptoms are present or not. MATERIALS AND METHODS: Magnetic resonance diffusion tractography in several individual white matter tracts that are involved in language and memory tasks, including tracts to cortical association areas, was applied in 21 patients with NPSLE (mean age: 40.7 ± 12.8 years; range: 22-67 years), 18 patients with non-neurologic systemic lupus erythematosus (non-NPSLE) (mean age: 40.6 ± 12 years; range: 22-67 years), and 20 healthy control (HC) individuals (mean age: 40.64 ± 12.7 years; range: 19-60 years). Additional patients were evaluated; however, because of the inability to complete the scans required, they were excluded from the study. The fractional anisotropy of individual fiber tracts was measured and correlated with cognitive function and lupus disease severity index (Systemic Lupus Erythematosus Disease Activity Index [SLEDAI]) to assess predictability and diagnostic value of these measures for NPSLE. RESULTS: Analyses of variance of the tractography data from the analysis of 21 tracts revealed decreased fractional anisotropy in uncinate fasciculus in the NPSLE patients when compared to non-NPSLE lupus patients and HC individuals (P = 0.002). Non-NPSLE patients also demonstrated decreased fractional anisotropy when compared to healthy patients (P = 0.03). Decreased fractional anisotropy was also identified in the corpus callosum and corona radiata in NPSLE patients when compared to HC individuals; however, these tracts did not show a significant difference between NPSLE and non-NPSLE patients. Decreased fractional anisotropy in the uncinate fasciculus correlated with low SLEDAI score (R2 = 0.32). CONCLUSIONS: Diffusion tensor tractography corroborates findings of decreased white matter integrity within the anterior corona radiate as well as the corpus callosum as previously described. Specifically, our study identified changes in the uncinate fasciculus in NPSLE and non-NPSLE patients that correlate with clinical changes (SLEDAI scores) and are independent of conventional T2 lesion burden.

Comparison of Diffusion Tensor Imaging and Magnetic Resonance Perfusion Imaging in Differentiating Recurrent Brain Neoplasm From Radiation Necrosis.

RATIONALE AND OBJECTIVES: To compare differences in diffusion tensor imaging (DTI) and dynamic susceptibility-weighted contrast-enhanced (DSC) magnetic resonance (MR) perfusion imaging characteristics of recurrent neoplasm and radiation necrosis in patients with brain tumors previously treated with radiotherapy with or without surgery and chemotherapy. MATERIALS AND METHODS: Patients with a history of brain neoplasm previously treated with radiotherapy with or without chemotherapy and surgery who developed a new enhancing lesion on posttreatment surveillance MRI were enrolled. DSC perfusion MRI and DTI were performed. Region of interest cursors were manually drawn in the contrast-enhancing lesions, in the perilesional white matter edema, and in the contralateral normal-appearing frontal lobe white matter. DTI and DSC perfusion MR indices were compared in recurrent tumor versus radiation necrosis. RESULTS: Twenty-two patients with 24 lesions were included. Sixteen (67%) lesions were placed into the recurrent neoplasm group and eight (33%) lesions were placed into the radiation necrosis group using biopsy results as the gold standard in all but three patients. Mean apparent diffusion coefficient values, mean parallel eigenvalues, and mean perpendicular eigenvalues in the contrast-enhancing lesion were significantly lower, and relative cerebral blood volume was significantly higher for the recurrent neoplasm group compared to the radiation necrosis group (P < 0.01, P = 0.03, P < 0.01, and P < 0.01, respectively). CONCLUSIONS: The combined assessment of DTI and DSC MR perfusion properties of new contrast-enhancing lesions is helpful in distinguishing recurrent neoplasm from radiation necrosis in patients with a history of brain neoplasm previously treated with radiotherapy with or without surgery and chemotherapy.

A physical simulator for endoscopic endonasal drilling techniques: technical note.

In this paper, the authors present a physical model developed to teach surgeons the requisite drilling techniques when using an endoscopic endonasal approach (EEA) to the skull base. EEA is increasingly used for treating pathologies of the ventral and ventrolateral cranial base. Endonasal drilling is a unique skill in terms of the instruments used, the long reach required, and the restricted angulation, and gaining competency requires much practice. Based on the successful experience in creating custom simulators, the authors used 3D printing to build an EEA training model from post-processed thin-cut head CT scans, formulating the materials to provide realistic haptic feedback and endoscope handling. They performed a preliminary assessment at 2 institutions to evaluate content validity of the simulator as the first step of the validation process. Overall results were positive, particularly in terms of bony landmarks and haptic response, though minor refinements were suggested prior to use as a training device.

Radiation safety and spine surgery: systematic review of exposure limits and methods to minimize radiation exposure.

BACKGROUND: Ionizing radiation is typically used during spine surgery for localization and guidance in instrumentation placement. Minimally invasive (MI) surgical procedures are increasingly popular and often require significantly more fluoroscopy, placing surgeons at risk for increased radiation exposure and radiation-induced complications. This study provides recommendations for minimizing risk of radiation-induced injury to spine surgeons and summarizes studies addressing radiation exposure in spine procedures. METHODS: The PubMed database was queried for relevant articles pertaining to radiation exposure in spine surgery. RESULTS: Discectomy, percutaneous pedicle screw placement, MI transforaminal lumbar interbody fusion, MI lateral lumbar interbody fusion, and vertebroplasty/kyphoplasty procedures were assessed. The highest radiation doses were seen with MI pedicle screw placement, MI transforaminal lumbar interbody fusion, vertebroplasty and kyphoplasty, and percutaneous endoscopic lumbar discectomy. Use of lead aprons and thyroid shields reduces effective dose by several orders of magnitude. Proper operator positioning also minimizes radiation exposure. Lead gloves decrease dose to the surgeon's hand from scatter if the hand is out of the x-ray beam most of the time. If prolonged exposure of the hand cannot be avoided, the technician should collimate the surgeon's hand out of the beam or use instruments to position the hand farther from the beam. In addition to using less fluoroscopy, pulsed fluoroscopy can decrease overall dose in a procedure. CONCLUSIONS: Spine surgeons should reduce their exposure to radiation to minimize risk of potential long-term complications. Strategies include minimizing fluoroscopy use and dose, proper use of protective gear, and appropriate manipulation of fluoroscopic equipment.

Diminished white matter integrity in patients with systemic lupus erythematosus.

PURPOSE: Systemic lupus erythematosus (SLE) is an autoimmune connective tissue disease that can affect the central nervous system. Neuropsychiatric symptoms are found in 25-70% of patients. Using diffusion tensor imaging (DTI) various studies have reported changes in white matter integrity in SLE patients with neuropsychiatric symptoms (NPSLE patients). The purpose of this study was to investigate, if regional changes in white matter integrity can also be detected in SLE patients without neuropsychiatric symptoms (non-NPSLE patients). METHODS: Applying DTI and tract based spatial statistics (TBSS) we investigated 19 NPSLE patients, 19 non-NPSLE and 18 healthy controls. Groups were matched for age and sex. Image pre-processing was performed using FSL, following the TBSS pipeline (eddy current correction, estimation of fractional anisotropy (FA), normalization, skeletonization of the group mean FA image). A general linear model with threshold-free cluster enhancement was used to assess significant differences between the three groups. RESULTS: Statistical analyses revealed several regions of decreased prefrontal white matter integrity (decreased FA) in both groups of SLE patients. The changes found in the non-NPSLE patients (as compared to healthy controls) overlapped with those in the NPSLE patients, but were not as pronounced. CONCLUSIONS: Our data suggest that changes in regional white matter integrity, in terms of a decrease in FA, are present not only in NPSLE patients, but also in non-NPSLE patients, though to a lesser degree. We also demonstrate that the way statistical maps are corrected for multiple comparisons has a profound influence on whether alterations in white matter integrity in non-NPSLE patients are deemed significant.

Sonographically guided lumbar puncture in pediatric patients.

Our aim with this study was to develop a user-friendly method for pediatric sonographically guided lumbar punctures so that we can visualize intrathecal anatomy, confirm intrathecal injection at the time of injection, and, most importantly, avoid ionizing radiation to a child's already radiosensitive pelvis. Sonographically guided lumbar puncture was prospectively performed in children aged 7 weeks to 16 years. All attempts (n = 9) were successful. We were able to identify relevant anatomy (including the conus in children 10 years and younger), confirm intrathecal injection, visualize intrathecal hematoma, and avoid radiation. Sonography is a promising modality for image-guided lumbar punctures without radiation in children.

Perfusion-weighted MR imaging in cerebral lupus erythematosus.

RATIONALE AND OBJECTIVE: Neuropsychiatric systemic lupus erythematosus (NPSLE) is a diagnostically challenging, severe, and life-threatening condition, which is currently lacking a "gold standard." Our aim with this study is to look for magnetic resonance (MR) perfusion differences in NPSLE, SLE, and healthy control (HC) patients and correlate our findings with clinical parameters. MATERIALS AND METHODS: Twenty-four NPSLE patients, 21 SLE patients, and 21 HC underwent dynamic susceptibility contrast enhanced MR perfusion using a 3-T scanner. Nine prospectively selected intracranial regions of interest were placed in white and gray matter and the cerebral blood flow (CBF), cerebral blood volume (CBV), and mean transit time (MTT) values were calculated. Subjects underwent clinical evaluation with SLEDAI and serum antibodies. RESULTS: The SLE patients had higher CBF and CBV compared to the HC overall (P = .01) and in specific areas (P = .03-.048). SLE patients with signs of active disease (elevated SLEDAI and anti-double-stranded DNA) had significantly elevated CBV, CBF, and MTT in the posterior cingulate gyrus (P = .01-.02). No significant difference was seen in the magnetic resonance perfusion measurements of NPSLE patients compared to SLE and HC, although the NPSLE patients also showed higher CBV variability compared to the SLE (P = .0004) and HC cohort (P < .0001). CONCLUSION: SLE patients have increased CBV and CBF compared to healthy controls. The SLE patients with clinical markers for active disease have elevated CBV, CBF, and MTT in the posterior cingulate gyrus. NPSLE patients show increased variability in perfusion measurements, which may explain why susceptibility contrast enhanced MRI has not yet provided a specific target for NPSLE.

Imaging of pregnant and lactating patients: part 1, evidence-based review and recommendations.

OBJECTIVE: The objectives of this article are to discuss the current evidence-based recommendations regarding radiation dose concerns, the use of iodinated and gadolinium-based contrast agents, and the comparative advantages of multimodality imaging (ultrasound, CT, and MRI) during pregnancy and lactation. We also discuss the use of imaging to evaluate pregnant trauma patients. CONCLUSION: Maternal and fetal radiation exposure and dose are affected by gestational age, anatomic site, modality, and technique. The use of iodinated and gadolinium-based contrast agents during pregnancy and lactation has not been well studied in human subjects. Imaging should be used to evaluate pregnant trauma patients only when the benefits outweigh the risks.

Imaging of pregnant and lactating patients: part 2, evidence-based review and recommendations.

OBJECTIVE: The objectives of this article are to discuss the current evidence-based recommendations regarding the use of diagnostic imaging in the evaluation of pulmonary embolism, appendicitis, urolithiasis, and cholelithiasis during pregnancy. CONCLUSION: Diagnostic imaging should be performed during pregnancy only with an understanding of the maternal and fetal risks and benefits, the comparative advantages of different modalities, and the unique anatomic and physiologic issues associated with pregnancy.

MRI findings for parotid lupus.

This report presents the MRI findings for parotid lupus erythematosus panniculitis. Although the clinical findings of this disorder have been described, very few reports describe the CT findings on this rare disease entity in the parotid region and no reports include its MR appearance. This unusual diagnosis should be considered in the context of proper clinical history.

Apprenticeships ease the transition to independent call: an evaluation of anxiety and confidence among junior radiology residents.

RATIONALE AND OBJECTIVES: The aims of this study were to quantify resident anxiety when beginning independent call and to assess whether an apprenticeship experience (buddy call) can lessen anxiety and improve confidence. MATERIALS AND METHODS: A prospective cohort comparison of two groups of radiology residents beginning independent call, one of which was provided with a buddy call experience, was performed. Anxiety and confidence were assessed using the Endler Multidimensional Anxiety Scales-State (EMAS-S), with total score, autonomic emotional, and cognitive worry components, and a five-point, Likert-type scale, respectively. Both groups were asked about the perceived value of a buddy call experience. RESULTS: EMAS-S scores improved significantly over 5 days of call in both groups (control, n = 10, P = .0005; buddy call, n = 9, P = .0001), and image interpretation confidence correspondingly increased (control, P = .0004; buddy call, P = .003). Compared to the control group, autonomic emotional scores were significantly lower in the buddy call group on the first day of independent call (P = .040), and cognitive worry and total EMAS-S scores were significantly lower on day 5 (both P values = .03). Buddy call was independently associated with improved autonomic emotional and film interpretation confidence scores (both P values = .02). All members of the buddy call group indicated that the experience was very helpful in preparing for call. CONCLUSIONS: Beginning independent call is associated with high anxiety, and buddy call reduces that anxiety, beyond the effect of time alone. Residents who participated in buddy call found it helpful in preparing for independent call. These findings support the use of buddy call and tiered call structures as means to introduce junior residents to independent call.

MOSFET dosimetry for radiation dose assessment of bismuth shielding of the eye in children.

OBJECTIVE: The purpose of our study was to measure radiation dose to the orbit during pediatric cranial CT with and without bismuth shielding using a novel dosimetry system. Cranial CT was performed on a pediatric anthropomorphic phantom, with and without bismuth eye shields. A solid-state metal oxide semiconductor field effect transistor (MOSFET) dosimeter was used to obtain real-time dose measurements. CONCLUSION: Bismuth shielding reduced radiation dose to the eye by up to 42%; shield artifact fell outside the diagnostic area of interest.

Craniosynostosis Secondary to Rickets: Manifestations on Computed Tomography.

We present the case of a preterm 6-month-old African American infant who developed craniosynostosis secondary to rickets. This child developed rickets and macrocephaly by the age of 6 months. His head continued to enlarge, and a 3D CT obtained when the child was 2 years old revealed metopic and bilateral coronal craniosynostosis. This CT suggested increased intracranial pressure, and therefore, corrective cranial vault reconstruction was performed. Craniosynostosis secondary to rickets is rarely reported, but since neither rickets nor craniosynostosis is a reportable disease, the exact incidence of both diseases is unknown. Craniosynostosis should be suspected in any rachitic child with an abnormal head circumference or shape and craniofacial CT evaluation should be performed, so that a corrective surgery can be performed at an appropriate age.