High Signal Intensity of the Cochlear Modiolus on Unenhanced T1-Weighted Images in Classical Infratentorial Superficial Siderosis.

Background: Superficial siderosis (SS) results from chronic bleeding in the subarachnoid space. SS can be classified as infratentorial SS (i-SS) and supratentorial SS (s-SS). The cochlear modiolus (CM) normally shows low signal intensity (SI) on Tl-weighted images (T1WI). We noticed persistently high SI of the CM on unenhanced thin-sliced T1WI in patients with i-SS. The purpose of this study was to evaluate the correlation between SS and high SI of the CM on unenhanced T1WI. Methods: This retrospective study analyzed three cases with i-SS, eight cases with s-SS, and 23 normal controls (NC) evaluated on unenhanced thin-sliced T1WI with a three-dimensional spoiled gradient-recalled echo sequence. CM-T1SI scores of 0, 1, and 2 indicated low, iso, and high SI, respectively. In cases with scores of 2 evaluated several times, all scores were reviewed for each case. The CM-T1SI ratio was defined as the contrast ratio between the CM and the cerebellum. Differences between the three groups were statistically analyzed based on the CM-T1SI score and ratio. Receiver operative curve (ROC) analysis was used to determine the cut-off values for differentiating the i-SS group from the NC group based on the CM-T1SI ratio. Results: Two patients with i-SS had a score of 2 on all evaluations. The CM-T1SI score and ratio differed significantly between the i-SS and NC groups. The accuracy of the CM-T1SI ratio for discriminating i-SS from NC was 98.9% at a cutoff value of 0.628. Conclusion: High SI of the CM on unenhanced TIWI can be an additional characteristic finding of i-SS.

The effect of group-dynamics, collaboration and tutor style on the perception of profession-based stereotypes: a quasi-experimental pre- post-design on interdisciplinary tutorial groups.

BACKGROUND: Group processes in inter-professional Problem-Based Learning (iPBL) groups have not yet been studied in the health-care educational context. In this paper we present findings on how group-dynamics, collaboration, and tutor style influence the perception of profession-based stereotypes of students collaborating in iPBL groups. Health-care students are trained in iPBL groups to increase their ability to collaborate with other healthcare professionals. Previous research focusing iPBL in healthcare implies that more systematic studies are desired, especially concerning the interaction between group processes and internalized professional stereotypes. The aim of this study is to investigate whether changes in group processes, collaboration, and tutor style, influence the perception of profession-based stereotypes of physician- and nursing-students. METHODS: The study is a quasi-experimental pre- post-design. The participants included 30 students from five different healthcare professions, mainly medicine and nursing. Other professions were physiotherapy, occupational therapy and speech therapy. The students were divided into four iPBL groups, each consisting of six to nine students and a tutor. Data were collected through systematic observation using four video-recorded tutorials. SPGR (Systematizing the Person Group Relation), a computer-supported method for direct and structured observation of behavior, was used to collect and analyze the data. RESULTS: Traditional stereotypical profession-based behaviors were identified in the first observed group meeting. Although the groups followed different paths of development, the group-dynamics changed in all groups over the 6 weeks of collaboration. Two of the groups became more cohesive, one became more fragmented and one became more polarized. Stereotypical behaviors became less frequent in all groups. Our findings indicate that tutor behavior has a strong influence on the development of the group's dynamics. CONCLUSION: Our findings strongly suggest iPBL is a means of reducing stereotypical behaviors, and may positively increase members' ability to engage in inter-professional collaboration. Although the pattern of dynamics took different forms in different groups, we argue that iPBL forces students to see the colleague behind his or her profession, thus breaking professional boundaries. The tutor style significantly influenced the iPBL groups' development. This study contributes to our field by emphasizing the effect of group-processes in increasing mutual understanding across professions.

Artifact reduction in free-breathing, free-running myocardial perfusion imaging with interleaved non-selective RF excitations.

PURPOSE: To reduce inflow and motion artifacts in free-breathing, free-running, steady-state spoiled gradient echo T1 -weighted (SPGR) myocardial perfusion imaging. METHOD: Unsaturated spins from inflowing blood or out-of-plane motion cause flashing artifacts in free-running SPGR myocardial perfusion. During free-running SPGR, 1 non-selective RF excitation was added after every 3 slice-selective RF excitations to suppress inflow artifacts by forcing magnetization in neighboring regions to steady-state. Bloch simulations and phantom experiments were performed to evaluate the impact of the flip angle and non-selective RF frequency on inflowing spins and tissue contrast. Free-running perfusion with (n = 11) interleaved non-selective RF or without (n = 11) were studied in 22 subjects (age = 60.2 ± 14.3 years, 11 male). Perfusion images were graded on a 5-point Likert scale for conspicuity of wall enhancement, inflow/motion artifact, and streaking artifact and compared using Wilcoxon sum-rank testing. RESULT: Numeric simulation showed that 1 non-selective RF excitation applied after every 3 slice-selective RF excitations produced superior out-of-plane signal suppression compared to 1 non-selective RF excitation applied after every 6 or 9 slice-selective RF excitations. In vitro experiments showed that a 30° flip angle produced near-optimal myocardial contrast. In vivo experiments demonstrated that the addition of interleaved non-selective RF significantly (P < .01) improved conspicuity of wall enhancement (mean score = 4.4 vs. 3.2) and reduced inflow/motion (mean score = 4.5 vs. 2.5) and streaking (mean score = 3.9 vs. 2.4) artifacts. CONCLUSION: Non-selective RF excitations interleaved between slice-selective excitations can reduce image artifacts in free-breathing, ungated perfusion images. Further studies are warranted to assess the diagnostic accuracy of the proposed solution for evaluating myocardial ischemia.

Application of 3D-FS-SPGR imaging combined synovial fluid GGCX detection in the evaluation of knee osteoarthritis.

BACKGROUND: Osteoarthritis represents a kind of chronic and degenerative joint disease characterized by articular cartilage injury and osteoproliferation. Osteoarthritis especially poses a serious threat to the elderly patients. At present, the diagnosis of osteoarthritis mainly consists of clinical examination, X-ray examination, magnetic resonance imaging (MRI), and arthroscopy. However, limitations and misdiagnosis are found within the single method. OBJECTIVES: This article intends to investigate the feasibility of assessing the condition of knee osteoarthritis through quantitative analysis of cartilage using nuclear magnetic resonance 3D fast-spin spoiled gradient-recalled echo (NMR 3D-FS-SPGR) imaging and γ-glutamic acid carboxylase (GGCX) detection in synovial fluid. MATERIAL AND METHODS: A total of 60 patients with primary knee osteoarthritis were enrolled. All the patients were staged and received 3D-FS-SPGR sequence MRI scan for grading based on scan results and cartilage injury. Cartilage tissues were collected for immunohistochemistry (IHC). The GGCX in cartilage was detected using western blotting to analyze the correlation with arthritis. RESULTS: The condition of articular cartilage injury in arthritis patients was clearly observed using 3D-FS-SPGR sequence. The expression of GGCX was decreased in 46 patients (p < 0.05). The expression of GGCX in synovial fluid was significantly reduced following upstaging (p < 0.05). The sensitivity measured using combined 3D-FS-SPGR imaging and synovial fluid GGCX detection for the evaluation of arthritis condition was significantly higher than that of the single detection method (p < 0.05). CONCLUSIONS: Our data showed that the sensitivity of combined detection was obviously higher than single detection for the evaluation of arthritis. The 3D-FS-SPGR combined with synovial fluid GGCX detection could be treated as a promising strategy for arthritis evaluation.

Whole-heart, ungated, free-breathing, cardiac-phase-resolved myocardial perfusion MRI by using Continuous Radial Interleaved simultaneous Multi-slice acquisitions at sPoiled steady-state (CRIMP).

PURPOSE: To develop a whole-heart, free-breathing, non-electrocardiograph (ECG)-gated, cardiac-phase-resolved myocardial perfusion MRI framework (CRIMP; Continuous Radial Interleaved simultaneous Multi-slice acquisitions at sPoiled steady-state) and test its quantification feasibility. METHODS: CRIMP used interleaved radial simultaneous multi-slice (SMS) slice groups to cover the whole heart in 9 or 12 short-axis slices. The sequence continuously acquired data without magnetization preparation, ECG gating or breath-holding, and captured multiple cardiac phases. Images were reconstructed by a motion-compensated patch-based locally low-rank reconstruction. Bloch simulations were performed to study the signal-to-noise ratio/contrast-to-noise ratio (SNR/CNR) for CRIMP and to study the steady-state signal under motion. Seven patients were scanned with CRIMP at stress and rest to develop the sequence. One human and two dogs were scanned at rest with a dual-bolus method to test the quantification feasibility of CRIMP. The dual-bolus scans were performed using both CRIMP and an ungated radial SMS saturation recovery (SMS-SR) sequence with injection dose = 0.075 mmol/kg to compare the sequences in terms of SNR, cardiac phase resolution and quantitative myocardial blood flow (MBF). RESULTS: Perfusion images with multiple cardiac phases in all image slices with a temporal resolution of 72 ms/frame were obtained. Simulations and in-vivo acquisitions showed CRIMP kept the inner slices in steady-state regardless of motion. CRIMP outperformed SMS-SR in slice coverage (9 over 6), SNR (mean 20% improvement), and provided cardiac phase resolution. CRIMP and SMS-SR sequences provided comparable MBF values (rest systolic CRIMP = 0.58 ± 0.07, SMS-SR = 0.61 ± 0.16). CONCLUSION: CRIMP allows for whole-heart, cardiac-phase-resolved myocardial perfusion images without ECG-gating or breath-holding. The sequence can provide MBF if an accurate arterial input function is obtained separately.

Ferumoxytol-enhanced MRI for surveillance of pediatric cerebral arteriovenous malformations.

OBJECTIVE: Children with intracranial arteriovenous malformations (AVMs) undergo digital DSA for lesion surveillance following their initial diagnosis. However, DSA carries risks of radiation exposure, particularly for the growing pediatric brain and over lifetime. The authors evaluated whether MRI enhanced with a blood pool ferumoxytol (Fe) contrast agent (Fe-MRI) can be used for surveillance of residual or recurrent AVMs. METHODS: A retrospective cohort was assembled of children with an established AVM diagnosis who underwent surveillance by both DSA and 3-T Fe-MRI from 2014 to 2016. Two neuroradiologists blinded to the DSA results independently assessed Fe-enhanced T1-weighted spoiled gradient recalled acquisition in steady state (Fe-SPGR) scans and, if available, arterial spin labeling (ASL) perfusion scans for residual or recurrent AVMs. Diagnostic confidence was examined using a Likert scale. Sensitivity, specificity, and intermodality reliability were determined using DSA studies as the gold standard. Radiation exposure related to DSA was calculated as total dose area product (TDAP) and effective dose. RESULTS: Fifteen patients were included in this study (mean age 10 years, range 3-15 years). The mean time between the first surveillance DSA and Fe-MRI studies was 17 days (SD 47). Intermodality agreement was excellent between Fe-SPGR and DSA (κ = 1.00) but poor between ASL and DSA (κ = 0.53; 95% CI 0.18-0.89). The sensitivity and specificity for detecting residual AVMs using Fe-SPGR were 100% and 100%, and using ASL they were 72% and 100%, respectively. Radiologists reported overall high diagnostic confidence using Fe-SPGR. On average, patients received two surveillance DSA studies over the study period, which on average equated to a TDAP of 117.2 Gy×cm2 (95% CI 77.2-157.4 Gy×cm2) and an effective dose of 7.8 mSv (95% CI 4.4-8.8 mSv). CONCLUSIONS: Fe-MRI performed similarly to DSA for the surveillance of residual AVMs. Future multicenter studies could further investigate the efficacy of Fe-MRI as a noninvasive alternative to DSA for monitoring AVMs in children.

Steady-state double-angle method for rapid B1 mapping.

PURPOSE: To introduce an accurate, rapid, and practical method for active B1 field mapping based on the double-angle method (DAM) in the steady-state (SS) signal regime. METHODS: We introduced and evaluated the performance of the SS-DAM approach to map the B1 field and compared the results to those calculated from the conventional DAM approach. Similar to DAM, SS-DAM uses the signal intensity ratio of 2 magnitude images acquired with different flip angles using the spoiled gradient recalled echo sequence. However, unlike DAM, in SS-DAM, these 2 spoiled gradient recalled echo images are acquired with very short TR, which allows substantially reduced acquisition time. Numerical, phantom, and in vivo brain imaging analyses, representing a wide range of T1 s and large B1 variation, were conducted. Methods for further accelerating acquisition were also investigated. RESULTS: Our results demonstrate the potential of the SS-DAM approach to be applied widely in the clinical setting. B1 maps derived from SS-DAM were demonstrated to be quantitatively comparable to those derived from DAM but were derived much more rapidly. Large-volume B1 maps were obtained at a field strength of 3 tesla within clinically acceptable acquisition times. CONCLUSION: SS-DAM permits accurate B1 mapping in the clinical setting, with whole-brain coverage in less than 1 min.

3-Tesla MRI of deep brain stimulation patients: safety assessment of coils and pulse sequences.

OBJECTIVE: Physicians are more frequently encountering patients who are treated with deep brain stimulation (DBS), yet many MRI centers do not routinely perform MRI in this population. This warrants a safety assessment to improve DBS patients' accessibility to MRI, thereby improving their care while simultaneously providing a new tool for neuromodulation research. METHODS: A phantom simulating a patient with a DBS neuromodulation device (DBS lead model 3387 and IPG Activa PC model 37601) was constructed and used. Temperature changes at the most ventral DBS electrode contacts, implantable pulse generator (IPG) voltages, specific absorption rate (SAR), and B1+rms were recorded during 3-T MRI scanning. Safety data were acquired with a transmit body multi-array receive and quadrature transmit-receive head coil during various pulse sequences, using numerous DBS configurations from "the worst" to "the most common."In addition, 3-T MRI scanning (T1 and fMRI) was performed on 41 patients with fully internalized and active DBS using a quadrature transmit-receive head coil. MR images, neurological examination findings, and stability of the IPG impedances were assessed. RESULTS: In the phantom study, temperature rises at the DBS electrodes were less than 2°C for both coils during 3D SPGR, EPI, DTI, and SWI. Sequences with intense radiofrequency pulses such as T2-weighted sequences may cause higher heating (due to their higher SAR). The IPG did not power off and kept a constant firing rate, and its average voltage output was unchanged. The 41 DBS patients underwent 3-T MRI with no adverse event. CONCLUSIONS: Under the experimental conditions used in this study, 3-T MRI scanning of DBS patients with selected pulse sequences appears to be safe. Generally, T2-weighted sequences (using routine protocols) should be avoided in DBS patients. Complementary 3-T MRI phantom safety data suggest that imaging conditions that are less restrictive than those used in the patients in this study, such as using transmit body multi-array receive coils, may also be safe. Given the interplay between the implanted DBS neuromodulation device and the MRI system, these findings are specific to the experimental conditions in this study.

Early outcomes of stereoelectroencephalography followed by MR-guided laser interstitial thermal therapy: a paradigm for minimally invasive epilepsy surgery.

OBJECTIVE Stereoelectroencephalography (sEEG) and MR-guided laser interstitial thermal therapy (MRgLITT) have both emerged as minimally invasive alternatives to open surgery for the localization and treatment of medically refractory lesional epilepsy. Although some data are available about the use of these procedures individually, reports are almost nonexistent on their use in conjunction. The authors' aim was to report early outcomes regarding efficacy and safety of sEEG followed by MRgLITT for localization and ablation of seizure foci in the pediatric population with medically refractory lesional epilepsy. METHODS A single-center retrospective review of pediatric patients who underwent sEEG followed by MRgLITT procedures was performed. Demographic, intraoperative, and outcome data were compiled and analyzed. RESULTS Four pediatric patients with 9 total lesions underwent sEEG followed by MRgLITT procedures between January and September 2017. The mean age at surgery was 10.75 (range 2-21) years. Two patients had tuberous sclerosis and 2 had focal cortical dysplasia. Methods of stereotaxy consisted of BrainLab VarioGuide and ROSA robotic guidance, with successful localization of seizure foci in all cases. The sEEG procedure length averaged 153 (range 67-235) minutes, with a mean of 6 (range 4-8) electrodes and 56 (range 18-84) contacts per patient. The MRgLITT procedure length averaged 223 (range 179-252) minutes. The mean duration of monitoring was 6 (range 4-8) days, and the mean total hospital stay was 8 (range 5-11) days. Over a mean follow-up duration of 9.3 (range 5.1-16) months, 3 patients were seizure free (Engel class I, 75%), and 1 patient saw significant improvement in seizure frequency (Engel class II, 25%). There were no complications. CONCLUSIONS These early data demonstrate that sEEG followed by MRgLITT can be used safely and effectively to localize and ablate epileptogenic foci in a minimally invasive paradigm for treatment of medically refractory lesional epilepsy in pediatric populations. Continued collection of data with extended follow-up is needed.

Neural responses to emotional involuntary memories in posttraumatic stress disorder: Differences in timing and activity.

Background: Involuntary memories are a hallmark symptom of posttraumatic stress disorder (PTSD), but studies of the neural basis of involuntary memory retrieval in posttraumatic stress disorder (PTSD) are sparse. The study of the neural correlates of involuntary memories of stressful events in PTSD focuses on the voluntary retrieval of memories that are sometimes recalled as intrusive involuntary memories, not on involuntary retrieval while being scanned. Involuntary memory retrieval in controls has been shown to elicit activity in the parahippocampal gyrus, precuneus, inferior parietal cortex, and posterior midline regions. However, it is unknown whether involuntary memories are supported by the same mechanisms in PTSD. Because previous work has shown that both behavioral and neural responsivity is slowed in PTSD, we examined the spatiotemporal dynamics of the neural activity underlying negative and neutral involuntary memory retrieval. Methods: Twenty-one individuals with PTSD and 21 non-PTSD, trauma-exposed controls performed an involuntary memory task, while undergoing a functional magnetic resonance imaging scan. Environmental sounds served as cues for well-associated pictures of negative and neutral scenes. We used a finite impulse response model to analyze temporal differences between groups in neural responses. Results: Compared with controls, participants with PTSD reported more involuntary memories, which were more emotional and more vivid, but which activated a similar network of regions. However, compared to controls, individuals with PTSD showed delayed neural responsivity in this network and increased vmPFC/ACC activity for negative > neutral stimuli. Conclusions: The similarity between PTSD and controls in neural substrates underlying involuntary memories suggests that, unlike voluntary memories, involuntary memories elicit similar activity in regions critical for memory retrieval. Further, the delayed neural responsivity for involuntary memories in PTSD suggests that factors affecting cognition in PTSD, like increased fatigue, or avoidance behaviors could do so by delaying activity in regions necessary for cognitive processing. Finally, compared to neutral memories, negative involuntary memories elicit hyperactivity in the vmPFC, whereas the vmPFC is typically shown to be hypoactive in PTSD during voluntary memory retrieval. These patterns suggest that considering both the temporal dynamics of cognitive processes as well as involuntary cognitive processes would improve existing neurobiological models of PTSD.

High-resolution 3D volumetric contrast-enhanced MR angiography with a blood pool agent (ferumoxytol) for diagnostic evaluation of pediatric brain arteriovenous malformations.

OBJECTIVE Patients with brain arteriovenous malformations (AVMs) often require repeat imaging with MRI or MR angiography (MRA), CT angiography (CTA), and digital subtraction angiography (DSA). The ideal imaging modality provides excellent vascular visualization without incurring added risks, such as radiation exposure. The purpose of this study is to evaluate the performance of ferumoxytol-enhanced MRA using a high-resolution 3D volumetric sequence (fe-SPGR) for visualizing and grading pediatric brain AVMs in comparison with CTA and DSA, which is the current imaging gold standard. METHODS In this retrospective cohort study, 21 patients with AVMs evaluated by fe-SPGR, CTA, and DSA between April 2014 and August 2017 were included. Two experienced raters graded AVMs using Spetzler-Martin criteria on all imaging studies. Lesion conspicuity (LC) and diagnostic confidence (DC) were assessed using a 5-point Likert scale, and interrater agreement was determined. The Kruskal-Wallis test was performed to assess the raters' grades and scores of LC and DC, with subsequent post hoc pairwise comparisons to assess for statistically significant differences between pairs of groups at p < 0.05. RESULTS Assigned Spetzler-Martin grades for AVMs on DSA, fe-SPGR, and CTA were not significantly different (p = 0.991). LC and DC scores were higher with fe-SPGR than with CTA (p < 0.05). A significant difference in LC scores was found between CTA and fe-SPGR (p < 0.001) and CTA and DSA (p < 0.001) but not between fe-SPGR and DSA (p = 0.146). A significant difference in DC scores was found among DSA, fe-SPGR, and CTA (p < 0.001) and between all pairs of the groups (p < 0.05). Interrater agreement was good to very good for all image groups (κ = 0.77-1.0, p < 0.001). CONCLUSIONS Fe-SPGR performed robustly in the diagnostic evaluation of brain AVMs, with improved visual depiction of AVMs compared with CTA and comparable Spetzler-Martin grading relative to CTA and DSA.

Comparison of MRI techniques for detecting microadenomas in Cushing's disease.

OBJECTIVE Many centers use conventional and dynamic contrast-enhanced MRI (DMRI) sequences in patients with Cushing's disease. The authors assessed the utility of the 3D volumetric interpolated breath-hold examination, a spoiled-gradient echo 3D T1 sequence (SGE) characterized by superior soft tissue contrast and improved resolution, compared with DMRI and conventional MRI (CMRI) for detecting microadenomas in patients with Cushing's disease. METHODS This study was a blinded assessment of pituitary MRI in patients with proven Cushing's disease. Fifty-seven patients who had undergone surgery for Cushing's disease (10 male, 47 female; age range 13-69 years), whose surgical findings were considered to represent a microadenoma, and who had been examined with all 3 imaging techniques were included. Thus, selection emphasized patients with prior negative or equivocal MRI on referral. The MRI annotations were anonymized and 4 separate imaging sets were independently read by 3 blinded, experienced clinicians: a neuroradiologist and 2 pituitary surgeons. RESULTS Forty-eight surgical specimens contained an adenoma (46 ACTH-staining adenomas, 1 prolactinoma, and 1 nonfunctioning microadenoma). DMRI detected 5 adenomas that were not evident on CMRI, SGE detected 8 adenomas not evident on CMRI, including 3 that were not evident on DMRI. One adenoma was detected on DMRI that was not detected on SGE. McNemar's test for efficacy between the different MRI sets for tumor detection showed that the addition of SGE to CMRI increased the number of tumors detected from 18 to 26 (p = 0.02) based on agreement of at least 2 of 3 readers. CONCLUSIONS SGE shows higher sensitivity than DMRI for detecting and localizing pituitary microadenomas, although rarely an adenoma is detected exclusively by DMRI. SGE should be part of the standard MRI protocol for patients with Cushing's disease.

Elaborate mapping of the posterior visual pathway in awake craniotomy.

OBJECTIVE Resection of intraaxial tumors adjacent to the optic radiation (OR) may be associated with postoperative visual field (VF) deficits. Intraoperative navigation using MRI-based tractography and electrophysiological monitoring of the visual pathways may allow maximal resection while preserving visual function. In this study, the authors evaluated the value of visual pathway mapping in a series of patients undergoing awake craniotomy for tumor resection. METHODS A retrospective analysis of prospectively collected data was conducted in 18 patients who underwent an awake craniotomy for resection of intraaxial tumors involving or adjacent to the OR. Preoperative MRI-based tractography was used for intraoperative navigation, and intraoperative acquisition of 3D ultrasonography images was performed for real-time imaging and correction of brain shift. Goggles with light-emitting diodes were used as a standard visual stimulus. Direct cortical visual evoked potential (VEP) recording, subcortical recordings from the OR, and subcortical stimulation of the OR were used intraoperatively to assess visual function and proximity of the lesion to the OR. VFs were assessed pre- and postoperatively. RESULTS Baseline cortical VEP recordings were available for 14 patients (77.7%). No association was found between preoperative VF status and baseline presence of cortical VEPs (p = 0.27). Five of the 14 patients (35.7%) who underwent subcortical stimulation of the OR reported seeing phosphenes in the corresponding contralateral VF. There was a positive correlation (r = 0.899, p = 0.04) between the subcortical threshold stimulation intensity (3-11.5 mA) and the distance from the OR. Subcortical recordings from the OR demonstrated a typical VEP waveform in 10 of the 13 evaluated patients (76.9%). These waveforms were present only when recordings were obtained within 10 mm of the OR (p = 0.04). Seven patients (38.9%) had postoperative VF deterioration, and it was associated with a length of < 8 mm between the tumor and the OR (p = 0.05). CONCLUSIONS Intraoperative electrophysiological monitoring of the visual pathways is feasible but may be of limited value in preserving the functional integrity of the posterior visual pathways. Subcortical stimulation of the OR may identify the location of the OR when done in proximity to the pathways, but such proximity may be associated with increased risk of postoperative worsening of the VF deficit.

Comparison of lesion enhancement between BB Cube and 3D-SPGR images for brain tumors with 1.5-T magnetic resonance imaging.

PURPOSE: This study aimed to compare the detectability of neoplastic lesion enhancement after gadolinium-based contrast media injection in three-dimensional T1-weighted black blood Cube (3D-T1W BB Cube) and three-dimensional T1-weighted fast spoiled gradient-echo (3D-T1W fast SPGR) images obtained with 1.5-T magnetic resonance imaging (MRI). MATERIALS AND METHODS: Phantom and clinical studies were performed to compare the lesion detectability and contrast ratio (CR) between 3D-T1W BB Cube and 3D-T1W fast SPGR pulse sequences. RESULTS: In the phantom study, the CRs for 3D-T1W BB Cube and 3D-T1W fast SPGR were equivalent at low gadolinium concentrations (0.125-1.25 mmol/l). In the clinical study, the detectability in the two modalities was similar for enhanced lesions ≥5 mm, but was significantly better in 3D-T1W BB Cube for lesions <5 mm (p = 0.011). Similarly, the CRs in both modalities were similar for lesions ≥5 mm (0.66 ± 0.36 vs. 0.56 ± 0.30, p = 0.153), but significantly lower in 3D-T1W BB Cube images for lesions <5 mm (0.29 ± 0.19 vs. 0.39 ± 0.21, p = 0.006). CONCLUSIONS: Contrast 3D-T1W BB Cube imaging appears more sensitive than 3D-T1W fast SPGR imaging for detecting neoplastic lesion enhancement in the clinical setting using a 1.5-T MRI scanner, particularly for lesions <5 mm in diameter.

Rapid and robust variable flip angle T1 mapping using interleaved two-dimensional multislice spoiled gradient echo imaging.

PURPOSE: Conventional T1 mapping using three-dimensional (3D) radiofrequency (RF) spoiled gradient echo (SPGR) imaging with short repetition times (TR) is adversely affected by incomplete spoiling (i.e. residual T2 dependency). In this work, an optimized interleaved 2D multislice SPGR sequence scheme and an adapted postprocessing procedure are evaluated for highly T2 -insensitive T1 quantification of human brain tissues. METHODS: An efficient 2D multislice SPGR protocol including a relatively long TR of 200 ms is investigated with careful consideration of cross talk and magnetization transfer effects. Based on the derived scan protocol, T1 is quantified from the signal ratio of two SPGR datasets acquired at different flip angles. The effect of nonideal RF excitation profiles is incorporated into the SPGR signal model by performing Bloch simulations. RESULTS: Simulations showed that the parameters of the SPGR protocol (such as TR and the spoiler gradient moments) guarantee virtually complete spoiling. This result was confirmed by T1 measurements both in vitro using a 2% agar probe doped with 0.1 mM Gd (Gadovist) and in vivo in the human brain. CONCLUSION: The derived 2D multislice SPGR protocol offers efficient, highly reproducible, and in particular T2 -insensitive T1 quantification of human brain tissues. Magn Reson Med 77:1606-1611, 2017. © 2016 International Society for Magnetic Resonance in Medicine.

Cushing's disease: pathobiology, diagnosis, and management.

Cushing's disease (CD) is the result of excess secretion of adrenocorticotropic hormone (ACTH) by a benign monoclonal pituitary adenoma. The excessive secretion of ACTH stimulates secretion of cortisol by the adrenal glands, resulting in supraphysiological levels of circulating cortisol. The pathophysiological levels of cortisol are associated with hypertension, diabetes, obesity, and early death. Successful resection of the CD-associated ACTH-secreting pituitary adenoma is the treatment of choice and results in immediate biochemical remission with preservation of pituitary function. Accurate and early identification of CD is critical for effective surgical management and optimal prognosis. The authors review the current pathophysiological principles, diagnostic methods, and management of CD.

Grade II meningiomas and Gamma Knife radiosurgery: analysis of success and failure to improve treatment paradigm.

OBJECTIVE Grade II meningiomas, which currently account for 25% of all meningiomas, are subject to multiple recurrences throughout the course of the disease and represent a challenge for the neurosurgeon. Radiosurgery is increasingly performed for the treatment of Grade II meningiomas and is quite efficient in controlling relapses locally at the site of the lesion, but it cannot prevent margin relapses. The aim of this retrospective study was to analyze the technical parameters involved in producing marginal relapses and to optimize loco-marginal control to improve therapeutic strategy. METHODS Eighteen patients presenting 58 lesions were treated by Gamma Knife radiosurgery (GKRS) between 2010 and 2015 in Hopital de la Pitié-Salpêtrière. The median patient age was 68 years (25%-75% interval: 61-72 years), and the sex ratio (M/F) was 13:5. The median delay between surgery and first GKRS was 3 years. Patients were classified as having Grade II meningioma using World Health Organization (WHO) 2007 criteria. The tumor growth rate was computed by comparing 2 volumetric measurements before treatment. After GKRS, iterative MRI, performed every 6 months, detected a relapse if tumor volume increased by more than 20%. Patterns of relapse were defined as being local, marginal, or distal. Survival curves were estimated using the Kaplan-Meier method, and the relationship between criterion and potential risk factors was tested by the log-rank test and univariable Cox model. RESULTS The median follow-up was 36 months (range 8-57 months). During this period, 3 patients presented with a local relapse, 5 patients with a marginal relapse, and 7 patients with a distal relapse. Crude local control was 84.5%. The local control actuarial rate was 89% at 1 year and 71% at 3 years. The marginal control actuarial rate was 81% at 1 year and 74% at 2 years. The distal control actuarial rate was 100% at 1 year, 81% at 2 years, and 53% at 3 years. Median distal control was 38 months. Progression-free survival (PFS) was 71% at 1 year, 36% at 2 years, and 23% at 3 years. Median PFS was 18 months. Lesions treated with a minimum radiation dose of ≤ 12 Gy had significantly more local relapses than those treated with a dose > 12 Gy (p = 0.04) in univariate analysis. Marginal control was significantly influenced by tumor growth rate, with a lower growth rate being highly associated with improved marginal control (p = 0.002). There was a trend toward a relationship between dose and marginal control, but it was not significant (p = 0.09). PFS was significantly associated with delay between first surgery and GKRS (p = 0.03). The authors noticed few complications with no sequelae. CONCLUSIONS In order to optimize loco-marginal control, radiosurgical treatment should require a minimum dose of > 12 Gy and an extended target volume along the dural insertion. Ideally, these parameters should correspond to the aggressiveness of the lesion, based on genetic features of the tumor.

Resecting critical nodes from an epileptogenic circuit in refractory focal-onset epilepsy patients using subtraction ictal SPECT coregistered to MRI.

OBJECTIVE The purpose of this study was to assess the positive predictive value of postresection outcomes obtained by presurgical subtracted ictal SPECT in patients with lesional (MRI positive) and nonlesional (MRI negative) refractory extratemporal lobe epilepsy (ETLE) and temporal lobe epilepsy (TLE). Specifically, outcomes were compared between partial versus complete resection of the regions of transient hyperperfusion identified using subtraction ictal SPECT coregistered to MRI (SISCOM) in relation to the ictal onset zone (IOZ) that was confirmed by electrocorticography (ECoG). That is, SISCOM was used to understand the long-term postsurgical outcomes following resection of the IOZ that overlapped with 1 or more regions of ictal onset-associated transient hyperperfusion. METHODS The study cohort included 44 consecutive patients with refractory ETLE or TLE who were treated between 2002 and 2013 and underwent presurgical evaluation using SISCOM. Concordance was determined between SISCOM localization and the IOZ on the basis of ECoG monitoring. In addition, the association between the extent of the resection site overlapping with the SISCOM signal and postresection outcomes were assessed. Postsurgical follow-up was longer than 24 months in 39 of 44 patients. RESULTS The dominant SISCOM signals were concordant with ECoG and overlapped the resection site in 32 of 44 (73%) patients (19 ETLE and 13 TLE patients), and 20 of 32 (63%) patients became seizure free. In all 19 ETLE patients with concordant SISCOM and ECoG results, the indicated location of ictal onset on ECoG was completely resected; 11 of 19 patients (58%) became seizure free (Engel Class I). In all 13 TLE patients with concordant SISCOM and ECoG results, the indicated ECoG focus was completely resected; 9 of 13 patients (69%) became seizure free (Engel Class I). Complete resection of the SISCOM signal was found in 7 of 34 patients (21%). Of these 7 patients, 5 patients (72%) were seizure free (Engel Class I). Partial resection of the SISCOM signal was found in 16 of 34 patients (47%), and 10 of these 16 patients (63%) were seizure free (Engel Class I) after more than 24 months of follow-up. CONCLUSIONS Concordance between 1 or more SISCOM regions of hyperperfusion with ECoG and at least partial resection of the dominant SISCOM signal in this refractory epilepsy cohort provided additional useful information for predicting long-term postresection outcomes. Such regions are likely critical nodes in more extensive, active, epileptogenic circuits. In addition, SPECT scanner technology may limit the sensitivity of meaningful SISCOM signals for identifying the maximal extent of the localizable epileptogenic network.

Intraoperative MRI-guided resection of focal cortical dysplasia in pediatric patients: technique and outcomes.

OBJECTIVE Previous meta-analysis has demonstrated that the most important factor in seizure freedom following surgery for focal cortical dysplasia (FCD) is completeness of resection. However, intraoperative detection of epileptogenic dysplastic cortical tissue remains a challenge, potentially leading to a partial resection and the need for reoperation. The objective of this study was to determine the role of intraoperative MRI (iMRI) in the intraoperative detection and localization of FCD as well as its impact on surgical decision making, completeness of resection, and seizure control outcomes. METHODS The authors retrospectively reviewed the medical records of pediatric patients who underwent iMRI-assisted resection of FCD at the Children's National Health System between January 2014 and April 2015. Data reviewed included demographics, length of surgery, details of iMRI acquisition, postoperative seizure freedom, and complications. Postsurgical seizure outcome was assessed utilizing the Engel Epilepsy Surgery Outcome Scale. RESULTS Twelve consecutive pediatric patients (8 females and 4 males) underwent iMRI-guided resection of FCD lesions. The mean age at the time of surgery was 8.8 years ± 1.6 years (range 0.7 to 18.8 years), and the mean duration of follow up was 3.5 months ± 1.0 month. The mean age at seizure onset was 2.8 years ± 1.0 year (range birth to 9.0 years). Two patients had Type 1 FCD, 5 patients had Type 2A FCD, 2 patients had Type 2B FCD, and 3 patients had FCD of undetermined classification. iMRI findings impacted intraoperative surgical decision making in 5 (42%) of the 12 patients, who then underwent further exploration of the resection cavity. At the time of the last postoperative follow-up, 11 (92%) of the 12 patients were seizure free (Engel Class I). No patients underwent reoperation following iMRI-guided surgery. CONCLUSIONS iMRI-guided resection of FCD in pediatric patients precluded the need for repeat surgery. Furthermore, it resulted in the achievement of complete resection in all the patients, leading to a high rate of postoperative seizure freedom.

Probabilistic machine learning for the evaluation of presurgical language dominance.

OBJECTIVE Providing a reliable assessment of language lateralization is an important task to be performed prior to neurosurgery in patients with epilepsy. Over the last decade, functional MRI (fMRI) has emerged as a useful noninvasive tool for language lateralization, supplementing or replacing traditional invasive methods. In standard practice, fMRI-based language lateralization is assessed qualitatively by visual inspection of fMRI maps at a specific chosen activation threshold. The purpose of this study was to develop and evaluate a new computational technique for providing the probability of each patient to be left, right, or bilateral dominant in language processing. METHODS In 76 patients with epilepsy, a language lateralization index was calculated using the verb-generation fMRI task over a wide range of activation thresholds (from a permissive threshold, analyzing all brain regions, to a harsh threshold, analyzing only the strongest activations). The data were classified using a probabilistic logistic regression method. RESULTS Concordant results between fMRI and Wada lateralization were observed in 89% of patients. Bilateral and right-dominant groups showed similar fMRI lateralization patterns differentiating them from the left-dominant group but still allowing classification in 82% of patients. CONCLUSIONS These findings present the utility of a semi-supervised probabilistic learning approach for presurgical language-dominance mapping, which may be extended to other cognitive domains such as memory and attention.