Improving advanced intraoperative MRI methods during pediatric neurosurgery.

Advanced intraoperative MR images (ioMRI) acquired during the resection of pediatric brain tumors could offer additional physiological information to preserve healthy tissue. With this work, we aimed to develop a protocol for ioMRI with increased sensitivity for arterial spin labeling (ASL) and diffusion MRI (dMRI), optimized for patient positioning regularly used in the pediatric neurosurgery setting. For ethical reasons, ASL images were acquired in healthy adult subjects that were imaged in the prone and supine position. After this, the ASL cerebral blood flow (CBF) was quantified and compared between both positions. To evaluate the impact of the RF coils setups on image quality, we compared different setups (two vs. four RF coils) by looking at T1-weighted (T1w) signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR), as well as undertaking a qualitative evaluation of T1w, T2w, ASL, and dMR images. Mean ASL CBF did not differ between the surgical prone and supine positions in any of the investigated regions of interest or the whole brain. T1w SNR (gray matter: p = 0.016, 34% increase; white matter: p = 0.016, 32% increase) and CNR were higher (p = 0.016) in the four versus two RF coils setups (18.0 ± 1.8 vs. 13.9 ± 1.8). Qualitative evaluation of T1w, T2w, ASL, and dMR images resulted in acceptable to good image quality and did not differ statistically significantly between setups. Only the nonweighted diffusion image maps and corticospinal tract reconstructions yielded higher image quality and reduced susceptibility artifacts with four RF coils. Advanced ioMRI metrics were more precise with four RF coils as the standard deviation decreased. Taken together, we have investigated the practical use of advanced ioMRI during pediatric neurosurgery. We conclude that ASL CBF quantification in the surgical prone position is valid and that ASL and dMRI acquisition with two RF coils can be performed adequately for clinical use. With four versus two RF coils, the SNR of the images increases, and the sensitivity to artifacts reduces.

Prophylactic pectoralis major flap to compensate for increased risk of pharyngocutaneous fistula in laryngectomy patients with low skeletal muscle mass (PECTORALIS): study protocol for a randomized controlled trial.

BACKGROUND: Total laryngectomy (TL) is a surgical procedure commonly performed on patients with advanced laryngeal or hypopharyngeal carcinoma. One of the most common postoperative complications following TL is the development of a pharyngocutaneous fistula (PCF), characterized by a communication between the neopharynx and the skin. PCF can lead to extended hospital stays, delayed oral feeding, and compromised quality of life. The use of a myofascial pectoralis major flap (PMMF) as an onlay technique during pharyngeal closure has shown potential in reducing PCF rates in high risk patients for development of PCF such as patients undergoing TL after chemoradiation and low skeletal muscle mass (SMM). Its impact on various functional outcomes, such as shoulder and neck function, swallowing function, and voice quality, remains less explored. This study aims to investigate the effectiveness of PMMF in reducing PCF rates in patients with low SMM and its potential consequences on patient well-being. METHODS: This multicenter study adopts a randomized clinical trial (RCT) design and is funded by the Dutch Cancer Society. Eligible patients for TL, aged ≥ 18 years, mentally competent, and proficient in Dutch, will be enrolled. One hundred and twenty eight patients with low SMM will be centrally randomized to receive TL with or without PMMF, while those without low SMM will undergo standard TL. Primary outcome measurement involves assessing PCF rates within 30 days post-TL. Secondary objectives include evaluating quality of life, shoulder and neck function, swallowing function, and voice quality using standardized questionnaires and functional tests. Data will be collected through electronic patient records. DISCUSSION: This study's significance lies in its exploration of the potential benefits of using PMMF as an onlay technique during pharyngeal closure to reduce PCF rates in TL patients with low SMM. By assessing various functional outcomes, the study aims to provide a comprehensive understanding of the impact of PMMF deployment. The anticipated results will contribute valuable insights into optimizing surgical techniques to enhance patient outcomes and inform future treatment strategies for TL patients. TRIAL REGISTRATION: NL8605, registered on 11-05-2020; International Clinical Trials Registry Platform (ICTRP).

Prevalence and 3-month follow-up of cerebrovascular MRI markers in hospitalized COVID-19 patients: the CORONIS study.

PURPOSE: To investigate the prevalence of cerebrovascular MRI markers in unselected patients hospitalized for COVID-19 (Coronavirus disease 2019), we compared these with healthy controls without previous SARS-CoV-2 infection or hospitalization and subsequently, investigated longitudinal (incidental) lesions in patients after three months. METHODS: CORONIS (CORONavirus and Ischemic Stroke) was an observational cohort study in adult hospitalized patients for COVID-19 and controls without COVID-19, conducted between April 2021 and September 2022. Brain MRI was performed shortly after discharge and after 3 months. Outcomes included recent ischemic (DWI-positive) lesions, previous infarction, microbleeds, white matter hyperintensities (WMH) and intracerebral hemorrhage and were analysed with logistic regression to adjust for confounders. RESULTS: 125 patients with COVID-19 and 47 controls underwent brain MRI a median of 41.5 days after symptom onset. DWI-positive lesions were found in one patient (1%) and in one (2%) control, both clinically silent. WMH were more prevalent in patients (78%) than in controls (62%) (adjusted OR: 2.95 [95% CI: 1.07-8.57]), other cerebrovascular MRI markers did not differ. Prevalence of markers in ICU vs. non-ICU patients was similar. After three months, five patients (5%) had new cerebrovascular lesions, including DWI-positive lesions (1 patient, 1.0%), cerebral infarction (2 patients, 2.0%) and microbleeds (3 patients, 3.1%). CONCLUSION: Overall, we found no higher prevalence of cerebrovascular markers in unselected hospitalized COVID-19 patients compared to controls. The few incident DWI-lesions were most likely to be explained by risk-factors of small vessel disease. In the general hospitalized COVID-19 population, COVID-19 shows limited impact on cerebrovascular MRI markers shortly after hospitalization.

Towards retrospective motion correction and reconstruction for clinical 3D brain MRI protocols with a reference contrast.

OBJECT: In a typical MR session, several contrasts are acquired. Due to the sequential nature of the data acquisition process, the patient may experience some discomfort at some point during the session, and start moving. Hence, it is quite common to have MR sessions where some contrasts are well-resolved, while other contrasts exhibit motion artifacts. Instead of repeating the scans that are corrupted by motion, we introduce a reference-guided retrospective motion correction scheme that takes advantage of the motion-free scans, based on a generalized rigid registration routine. MATERIALS AND METHODS: We focus on various existing clinical 3D brain protocols at 1.5 Tesla MRI based on Cartesian sampling. Controlled experiments with three healthy volunteers and three levels of motion are performed. RESULTS: Radiological inspection confirms that the proposed method consistently ameliorates the corrupted scans. Furthermore, for the set of specific motion tests performed in this study, the quality indexes based on PSNR and SSIM shows only a modest decrease in correction quality as a function of motion complexity. DISCUSSION: While the results on controlled experiments are positive, future applications to patient data will ultimately clarify whether the proposed correction scheme satisfies the radiological requirements.

Improving the lesion appearance on FLAIR images synthetized from quantitative MRI: a fast, hybrid approach.

OBJECTIVE: The image quality of synthetized FLAIR (fluid attenuated inversion recovery) images is generally inferior to its conventional counterpart, especially regarding the lesion contrast mismatch. This work aimed to improve the lesion appearance through a hybrid methodology. MATERIALS AND METHODS: We combined a full brain 5-min MR-STAT acquisition followed by FLAIR synthetization step with an ultra-under sampled conventional FLAIR sequence and performed the retrospective and prospective analysis of the proposed method on the patient datasets and a healthy volunteer. RESULTS: All performance metrics of the proposed hybrid FLAIR images on patient datasets were significantly higher than those of the physics-based FLAIR images (p < 0.005), and comparable to those of conventional FLAIR images. The small difference between prospective and retrospective analysis on a healthy volunteer demonstrated the validity of the retrospective analysis of the hybrid method as presented for the patient datasets. DISCUSSION: The proposed hybrid FLAIR achieved an improved lesion appearance in the clinical cases with neurological diseases compared to the physics-based FLAIR images, Future prospective work on patient data will address the validation of the method from a diagnostic perspective by radiological inspection of the new images over a larger patient cohort.

Synthetic MRI with Magnetic Resonance Spin TomogrAphy in Time-Domain (MR-STAT): Results from a Prospective Cross-Sectional Clinical Trial.

BACKGROUND: Magnetic Resonance Spin TomogrAphy in Time-domain (MR-STAT) can reconstruct whole-brain multi-parametric quantitative maps (eg, T1 , T2 ) from a 5-minute MR acquisition. These quantitative maps can be leveraged for synthetization of clinical image contrasts. PURPOSE: The objective was to assess image quality and overall diagnostic accuracy of synthetic MR-STAT contrasts compared to conventional contrast-weighted images. STUDY TYPE: Prospective cross-sectional clinical trial. POPULATION: Fifty participants with a median age of 45 years (range: 21-79 years) consisting of 10 healthy participants and 40 patients with neurological diseases (brain tumor, epilepsy, multiple sclerosis or stroke). FIELD STRENGTH/SEQUENCE: 3T/Conventional contrast-weighted imaging (T1 /T2 weighted, proton density [PD] weighted, and fluid-attenuated inversion recovery [FLAIR]) and a MR-STAT acquisition (2D Cartesian spoiled gradient echo with varying flip angle preceded by a non-selective inversion pulse). ASSESSMENT: Quantitative T1 , T2 , and PD maps were computed from the MR-STAT acquisition, from which synthetic contrasts were generated. Three neuroradiologists blinded for image type and disease randomly and independently evaluated synthetic and conventional datasets for image quality and diagnostic accuracy, which was assessed by comparison with the clinically confirmed diagnosis. STATISTICAL TESTS: Image quality and consequent acceptability for diagnostic use was assessed with a McNemar's test (one-sided α = 0.025). Wilcoxon signed rank test with a one-sided α = 0.025 and a margin of Δ = 0.5 on the 5-level Likert scale was used to assess non-inferiority. RESULTS: All data sets were similar in acceptability for diagnostic use (≥3 Likert-scale) between techniques (T1 w:P = 0.105, PDw:P = 1.000, FLAIR:P = 0.564). However, only the synthetic MR-STAT T2 weighted images were significantly non-inferior to their conventional counterpart; all other synthetic datasets were inferior (T1 w:P = 0.260, PDw:P = 1.000, FLAIR:P = 1.000). Moreover, true positive/negative rates were similar between techniques (conventional: 88%, MR-STAT: 84%). DATA CONCLUSION: MR-STAT is a quantitative technique that may provide radiologists with clinically useful synthetic contrast images within substantially reduced scan time. EVIDENCE LEVEL: 1 Technical Efficacy: Stage 2.

Cerebral Collateral Circulation in the Era of Reperfusion Therapies for Acute Ischemic Stroke.

Clinical outcomes of patients with acute ischemic stroke depend in part on the extent of their collateral circulation. A good collateral circulation has also been associated with greater benefit of intravenous thrombolysis and endovascular treatment. Treatment decisions for these reperfusion therapies are increasingly guided by a combination of clinical and imaging parameters, particularly in later time windows. Computed tomography and magnetic resonance imaging enable a rapid assessment of both the collateral extent and cerebral perfusion. Yet, the role of the collateral circulation in clinical decision-making is currently limited and may be underappreciated due to the use of rather coarse and rater-dependent grading methods. In this review, we discuss determinants of the collateral circulation in patients with acute ischemic stroke, report on commonly used and emerging neuroimaging techniques for assessing the collateral circulation, and discuss the therapeutic and prognostic implications of the collateral circulation in relation to reperfusion therapies for acute ischemic stroke.

Labyrinthine fistulas: Surgical outcomes and an additional diagnostic strategy.

PURPOSE: To evaluate perioperative findings and audiological and vestibular outcomes in patients operated for cholesteatoma with labyrinthine fistulas. Also to assess radiological fistula size. MATERIALS AND METHODS: Patients who underwent surgery for a labyrinthine fistula caused by a cholesteatoma between 2015 and 2020 in a tertiary referral center were retrospectively investigated. Fistula size was determined on preoperative CT scan. Bone and air conduction pure tone average thresholds were obtained pre- and postoperatively. Clinical outcomes, such as vertigo and otorrea were also evaluated. Main purpose was to determine whether there is a correlation between fistula size and postoperative hearing. Furthermore, perioperative findings and vestibular outcomes are evaluated. RESULTS: 21 patients (22 cases) with a labyrinthine fistula were included. There was no significant change after surgery in bone conduction pure tone average (preoperatively 27.6 dB ± 26.7; postoperatively 30.3 dB ± 34.3; p = 0.628) or air conduction pure tone average (preoperatively 58.7 dB ± 24.3; postoperatively 60.2 dB ± 28.3; p = 0.816). Fistula size was not correlated to postoperative hearing outcome. There were two patients with membranous labyrinth invasion: one patient was deaf preoperatively, the other acquired total sensorineural hearing loss after surgery. CONCLUSIONS: Sensorineural hearing loss after cholesteatoma surgery with labyrinthine fistula is rare. Fistula size and postoperative hearing loss are not correlated, however, membranous labyrinthine invasion seems to be related to poor postoperative hearing outcomes. Therefore, additional preoperative radiological work up, by MRI scan, in selected cases is advocated to guide the surgeon to optimize preoperative counselling.

Radiological and surgical aspects of round window visibility during cochlear implantation: a retrospective analysis.

PURPOSE: The round window approach has become the most preferred option for cochlear implant (CI) insertion, however, sometimes it may not be possible due to the (in)visibility of the round window membrane (RWM). We addressed the prevalence, consequences and indicators of difficult detection of the RWM in cochlear implant surgery. METHODS: This study retrospectively analysed the operative reports and preoperative high resolution axial-computed tomography (CT) scans of a consecutive cohort of patients who underwent a CI insertion. The main outcomes were surgical outcomes of the RW approach, and assessment of radiological markers. RESULTS: The operative reports showed that RWM insertion was feasible in 151 out of 153 patients. In 18% of the patients the RWM was difficult to visualize. All these patients had at least one intraoperative event. The chorda tympani nerve (CTN) or posterior canal wall was affected in 8% of the 153 patients and the fallopian canal in 6%. These patients had a facial-chorda tympani nerve distance on the CT scan that was considerably smaller than normal patients (1.5 mm vs 2.3 mm). In addition, a prediction line towards the anterolateral side of the RWM was found to be more prevalent in these patients' CT scans (sensitivity 81%, specificity 63%). CONCLUSION: The RW approach is feasible in almost all patients undergoing CI surgery. Difficult visualisation of the RWM seems to lead to at least one intraoperative event. Radiological measures showed that these patients had a smaller facial recess and a more anteriorly placed facial nerve, which can be used to better plan a safe insertion approach.

Perfusion imaging with arterial spin labeling (ASL)-MRI predicts malignant progression in low­grade (WHO grade II) gliomas.

PURPOSE: Predicting malignant progression of grade II gliomas would allow for earlier initiation of treatment. The hypothesis for this single-centre, case-control study was that the perfusion signal on ASL-MRI predicts such malignant progression in the following 12 months. METHODS: Consecutive patients with the following criteria were included: ≥ 18 years, grade II glioma (biopsied or resected) and an ASL-MRI 6-12 months prior to malignant progression (cases) or stable disease (controls). Malignant progression was defined either radiologically (new T1w-contrast enhancement) or histologically (neurosurgical tissue sampling). Three controls were matched with each case. Some patients served as their own control by using earlier imaging. The ASL-MRIs were reviewed by two neuroradiologists and classified as positive (hyper-intense or iso-intense compared to cortical grey matter) or negative (hypo-intense). In patients with epilepsy, a neurologist reviewed clinicoradiological data to exclude peri-ictal pseudoprogression. The statistical analysis included diagnostic test properties, a Cohen's Kappa interrater reliability coefficient and stratification for previous radiotherapy. RESULTS: Eleven cases (median age = 48, IQR = 43-50 years) and 33 controls (43, 27-50 years) were included. Malignant progression appeared at 37 months (median, IQR = 17-44) after first surgery. Thirty ASL-MRIs were assessed as negative and 14 as positive. None of the MRIs showed signs of peri-ictal pseudoprogression. ASL significantly predicted subsequent malignant progression (sensitivity = 73%; specificity = 82%; OR = 12; 95%-CI = 2.4-59.1; p = 0.002). The interrater reliability coefficient was 0.65. In stratified analysis, ASL-MRI predicted malignant progression both in patients with previous radiotherapy and in those without (Mantel-Haenszel test, p = 0.003). CONCLUSION: Perfusion imaging with ASL-MRI can predict malignant progression within 12 months in patients with grade II glioma.

Histology and computed tomography of incidental calcifications in the human basal ganglia.

Incidental basal ganglia calcifications are a common finding on computed tomography (CT). We investigated the histological characteristics of these calcifications and their association with CT findings, using post-mortem basal ganglia tissue from 22 patients. Eight patients had basal ganglia calcifications on histology, and six patients had calcifications on CT, varying from mild to severe. Four patients had calcifications identified by both histology and CT, and two patients had calcifications detected by CT but not by histology, possibly because of insufficient tissue available. Calcifications were found mainly in the tunica media of arterioles located in the globus pallidus, which suggests that incidental CT calcifications are vascular in nature. However, tunica media calcifications, and thereby incidental basal ganglia calcifications, are probably not related to atherosclerosis.

Virtual monochromatic dual-energy CT reconstructions improve detection of cerebral infarct in patients with suspicion of stroke.

PURPOSE: Early infarcts are hard to diagnose on non-contrast head CT. Dual-energy CT (DECT) may potentially increase infarct differentiation. The optimal DECT settings for differentiation were identified and evaluated. METHODS: One hundred and twenty-five consecutive patients who presented with suspected acute ischemic stroke (AIS) and underwent non-contrast DECT and subsequent DWI were retrospectively identified. The DWI was used as reference standard. First, virtual monochromatic images (VMI) of 25 patients were reconstructed from 40 to 140 keV and scored by two readers for acute infarct. Sensitivity, specificity, positive, and negative predictive values for infarct detection were compared and a subset of VMI energies were selected. Next, for a separate larger cohort of 100 suspected AIS patients, conventional non-contrast CT (NCT) and selected VMI were scored by two readers for the presence and location of infarct. The same statistics for infarct detection were calculated. Infarct location match was compared per vascular territory. Subgroup analyses were dichotomized by time from last-seen-well to CT imaging. RESULTS: A total of 80-90 keV VMI were marginally more sensitive (36.3-37.3%) than NCT (32.4%; p > 0.680), with marginally higher specificity (92.2-94.4 vs 91.1%; p > 0.509) for infarct detection. Location match was superior for VMI compared with NCT (28.7-27.4 vs 19.5%; p < 0.010). Within 4.5 h from last-seen-well, 80 keV VMI more accurately detected infarct (58.0 vs 54.0%) and localized infarcts (27.1 vs 11.9%; p = 0.004) than NCT, whereas after 4.5 h, 90 keV VMI was more accurate (69.3 vs 66.3%). CONCLUSION: Non-contrast 80-90 keV VMI best differentiates normal from infarcted brain parenchyma.

Detecting Bone Invasion of the Maxilla by Oral Squamous Cell Carcinoma: Diagnostic Accuracy of Preoperative Computed Tomography Versus Magnetic Resonance Imaging.

PURPOSE: For planning of the surgical resection, computed tomography (CT) and magnetic resonance imaging (MRI) are commonly used for the preoperative assessment of bone invasion of the maxilla. The purpose of this study was to compare the diagnostic test accuracy of CT and MRI for detecting bone invasion of the maxilla in patients with squamous cell carcinoma of the maxilla (MSCC). MATERIALS AND METHODS: We conducted a retrospective cross-sectional study and enrolled a consecutive number of patients with primary MSCC between 2000 and 2017 who underwent either preoperative CT or MRI scans. The outcome variable was the absence or presence of bone invasion, with histopathologic examination of the resection specimen as the gold standard. The predictor variable was the imaging technique (CT and MRI). The imaging results on bone invasion were compared with the histopathologic results. Sensitivity and specificity were calculated, and the 2-sided Fisher exact test was used to calculate statistically significant differences between the unpaired CT and MRI results. Receiver operating characteristic curves were computed, and the area under the curve (AUC) was calculated. RESULTS: The study included 72 patients (29 male and 43 female patients) with a mean age of 72 years. A total of 41 CT scans and 31 MRI scans were available. Histopathologic examination showed bone invasion in 45 cases: 26 of 41 patients with CT scans (63%) and 19 of 31 patients with MRI scans (61%). CT yielded 2 false-positive and 2 false-negative results, with a sensitivity of 92%, specificity of 87%, and AUC of 0.895. MRI yielded 5 false-positive and 2 false-negative results, with a sensitivity of 89%, specificity of 58%, and AUC of 0.739. No significant differences were observed for sensitivity (P > .999) and specificity (P = .185). CONCLUSIONS: In the absence of metallic dental restorations, CT could detect bone invasion more accurately than MRI in this study; however, the difference was not statistically significant. The imaging method of choice may depend on other situational factors.

Prevalence and vascular risk factors of basal ganglia calcifications in patients at risk for cerebrovascular disease.

BACKGROUND AND PURPOSE: Risk factors for and meaning of basal ganglia calcifications outside Fahr syndrome are poorly understood. We aimed to assess the prevalence of basal ganglia calcifications and the association with vascular risk factors. MATERIALS AND METHODS: 1133 patients suspected of acute ischemic stroke from the Dutch acute stroke (DUST) study who underwent thin-slice unenhanced brain CT were analyzed. Basal ganglia calcifications were scored bilaterally as absent, mild (dot), moderate (multiple dots or single artery) and severe (confluent). Uni- and multivariable logistic regression analysis was used to determine possible risk factors (age, gender, history of stroke, smoking, hypertension, diabetes mellitus, hyperlipidemia, body mass index (BMI), renal function and family history of cardiovascular disease under 60 years) for presence of basal ganglia calcifications and ordinal regression analysis for severity of basal ganglia calcifications. RESULTS: Mean age was 67.4 years (SD: 13.8), 56.8% were male. 337 (29.7%) patients had basal ganglia calcifications, of which 196 (58%) were mild, 103 (31%) moderate, 38 (11%) severe. In multivariable logistic regression analysis, age (OR: 1.02, 95% CI 1.01-1.03, P < 0.01) and BMI (OR: 0.95, 95% CI 0.91-0.98, p 0.01) were significantly associated with the presence of basal ganglia calcifications. Ordinal regression analysis gave comparable results. Age (OR: 1.02, 95% CI 1.01-1.03, P < 0.01) and BMI (OR: 0.95, 95% CI 0.92-0.99, P 0.01) were significantly associated with severity of basal ganglia calcifications. CONCLUSIONS: In this study with patients suspected of acute ischemic stroke, basal ganglia calcifications were common and significantly associated with older age and lower BMI.

Perfusion MRI in treatment evaluation of glioblastomas: Clinical relevance of current and future techniques.

Treatment evaluation of patients with glioblastomas is important to aid in clinical decisions. Conventional MRI with contrast is currently the standard method, but unable to differentiate tumor progression from treatment-related effects. Pseudoprogression appears as new enhancement, and thus mimics tumor progression on conventional MRI. Contrarily, a decrease in enhancement or edema on conventional MRI during antiangiogenic treatment can be due to pseudoresponse and is not necessarily reflective of a favorable outcome. Neovascularization is a hallmark of tumor progression but not for posttherapeutic effects. Perfusion-weighted MRI provides a plethora of additional parameters that can help to identify this neovascularization. This review shows that perfusion MRI aids to identify tumor progression, pseudoprogression, and pseudoresponse. The review provides an overview of the most applicable perfusion MRI methods and their limitations. Finally, future developments and remaining challenges of perfusion MRI in treatment evaluation in neuro-oncology are discussed. Level of Evidence: 3 Technical Efficacy: Stage 4 J. Magn. Reson. Imaging 2019;49:11-22.

Identifying perfusion deficits on CT perfusion images using temporal similarity perfusion (TSP) mapping.

OBJECTIVES: Deconvolution-derived maps of CT perfusion (CTP) data may be confounded by transit delays. We propose temporal similarity perfusion (TSP) analysis to decrease CTP maps' dependence on transit times and investigate its sensitivity to detect perfusion deficits. METHODS: CTP data of acute stroke patients obtained within 9 h of symptom onset was analyzed using a delay-insensitive singular value decomposition method and with TSP. The TSP method applies an iterative process whereby a pixel's highest Pearson's R value is obtained through comparison of a pixel's time-shifted signal density time-series curve and the average whole brain signal density time-series curve. Our evaluation included a qualitative and quantitative rating of deconvolution maps (MTT, CBV, and TTP), of TSP maps, and of follow-up CT. RESULTS: Sixty-five patients (mean 68 (SD 13) years, 34 male) were included. A perfusion deficit was identified in 90%, 86%, 65%, and 84% of MTT, TTP, CBV, and TSP maps. The agreement of MTT, TTP, and TSP with CT follow-up was comparable but noticeably lower for CBV. CBV had the best relationship with final infarct volume (R2 = 0.77, p < 0.001), followed by TSP (R2 = 0.63, p < 0.001). Intra-rater agreement of an inexperienced reader was higher for TSP than for CBV/MTT maps (kappa's of 0.79-0.84 and 0.63-0.7). Inter-rater agreement for experienced readers was comparable across maps. CONCLUSIONS: TSP maps are easier to interpret for inexperienced readers. Perfusion deficits detected by TSP are smaller which may suggest less dependence on transit delays although more investigation is required. KEY POINTS: • Temporal similarity perfusion mapping assesses CTP data based on similarities in signal time-curves. • TSP maps are comparable in perfusion deficit detection to deconvolution maps. • TSP maps are easier to interpret for inexperienced readers.

Induced Hypertension for Delayed Cerebral Ischemia After Aneurysmal Subarachnoid Hemorrhage: A Randomized Clinical Trial.

BACKGROUND AND PURPOSE: Induced hypertension is widely used to treat delayed cerebral ischemia (DCI) after aneurysmal subarachnoid hemorrhage, but a literature review shows that its presumed effectiveness is based on uncontrolled case-series only. We here report clinical outcome of aneurysmal subarachnoid hemorrhage patients with DCI included in a randomized trial on the effectiveness of induced hypertension. METHODS: Aneurysmal subarachnoid hemorrhage patients with clinical symptoms of DCI were randomized to induced hypertension or no induced hypertension. Risk ratios for poor outcome (modified Rankin Scale score >3) at 3 months, with 95% confidence intervals, were calculated and adjusted for age, clinical condition at admission and at time of DCI, and amount of blood on initial computed tomographic scan with Poisson regression analysis. RESULTS: The trial aiming to include 240 patients was ended, based on lack of effect on cerebral perfusion and slow recruitment, when 21 patients had been randomized to induced hypertension, and 20 patients to no hypertension. With induced hypertension, the adjusted risk ratio for poor outcome was 1.0 (95% confidence interval, 0.6-1.8) and the risk ratio for serious adverse events 2.1 (95% confidence interval, 0.9-5.0). CONCLUSIONS: Before this trial, the effectiveness of induced hypertension for DCI in aneurysmal subarachnoid hemorrhage patients was unknown because current literature consists only of uncontrolled case series. The results from our premature halted trial do not add any evidence to support induced hypertension and show that this treatment can lead to serious adverse events. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT01613235.

Computed Tomography Perfusion Derived Blood-Brain Barrier Permeability Does Not Yet Improve Prediction of Hemorrhagic Transformation.

INTRODUCTION: Hemorrhagic transformation (HT) in acute ischemic stroke can occur as a result of reperfusion treatment. While withholding treatment may be warranted in patients with increased risk of HT, prediction of HT remains difficult. Nonlinear regression analysis can be used to estimate blood-brain barrier permeability (BBBP). The aim of this study was to identify a combination of clinical and imaging variables, including BBBP estimations, that can predict HT. MATERIALS AND METHODS: From the Dutch acute stroke study, 545 patients treated with intravenous recombinant tissue plasminogen activator and/or intra-arterial treatment were selected, with available admission extended computed tomography (CT) perfusion and follow-up imaging. Patient admission treatment characteristics and CT imaging parameters regarding occlusion site, stroke severity, and BBBP were recorded. HT was assessed on day 3 follow-up imaging. The association between potential predictors and HT was analyzed using univariate and multivariate logistic regression. To compare the added value of BBBP, areas under the curve (AUCs) were created from 2 models, with and without BBBP. RESULTS: HT occurred in 57 patients (10%). In univariate analysis, older age (OR 1.03, 95% CI 1.006-1.05), higher admission National Institutes of Health Stroke Scale (NIHSS; OR 1.13, 95% CI 1.08-1.18), higher clot burden (OR 1.28, 95% CI 1.16-1.41), poor collateral score (OR 3.49, 95% CI 1.85-6.58), larger Alberta Stroke Program Early CT Score cerebral blood volume deficit size (OR 1.26, 95% CI 1.14-1.38), and increased BBBP (OR 2.22, 95% CI 1.46-3.37) were associated with HT. In multivariate analysis with age and admission NIHSS, the addition of BBBP did not improve the AUC compared to both independent predictors alone (AUC 0.77, 95% CI 0.71-0.83). CONCLUSION: BBBP predicts HT but does not improve prediction with age and admission NIHSS.

Prediction of ultrasound guided fine needle aspiration cytology results by FDG PET-CT for lymph node metastases in head and neck squamous cell carcinoma patients.

INTRODUCTION: Accurate assessment of cervical lymph node status is essential in patients with head and neck squamous cell carcinoma (HNSCC) as it influences prognosis and treatment decisions. During patient workup, lymph node status is often examined by ultrasound guided fine needle aspiration cytology (USgFNAC). 18F-Fluorodeoxyglucose positron emission tomography combined with computed tomography (FDG PET-CT) is frequently used to assess primary tumor and distant metastases but provides information on lymph node status as well. It is possible that FDG PET-CT (if already made for abovementioned indications) can predict the results of USgFNAC in subgroups of lymph nodes based on FDG-uptake and size. The objective of this study is to identify maximum standardized uptake (SUVmax) and short axis diameter cutoff values of lymph nodes at which FDG PET-CT can reliably predict USgFNAC results. METHODS: One hundred and seventeen patients with HNSCC were retrospectively analyzed. Patients were included when FDG PET-CT and USgFNAC were available. SUVmax measurements were performed and compared to the USgFNAC results. RESULTS: Using USgFNAC as a reference standard, the area under the curve of the receiver operating curve was 0.91. At an SUVmax cutoff value of 4.9, the accuracy of FDG PET-CT was the highest (85%). Lymph nodes with short axis diameter ≥1.0 cm and SUVmax ≥4.9 were in 91% positive on USgFNAC. If SUVmax was below 2.2, no nodes were positive on USgFNAC. Of all lymph nodes 52% either had a short axis diameter ≥1.0 cm and SUVmax ≥4.9 or an SUVmax <2.2. FDG PET-CT and USgFNAC results were very similar in these nodes. CONCLUSIONS: By measuring SUVmax values and minimal axial diameters of lymph nodes and using appropriate cutoff values, FDG PET-CT can predict the results of USgFNAC examinations in half of the examined lymph nodes. This information may lead to a reduction of USgFNAC examinations in HNSCC patients if FDG PET-CT is already performed for other indications.

Permeable Thrombi Are Associated With Higher Intravenous Recombinant Tissue-Type Plasminogen Activator Treatment Success in Patients With Acute Ischemic Stroke.

BACKGROUND AND PURPOSE: Preclinical studies showed that thrombus permeability improves recombinant tissue-type plasminogen activator (r-tPA) efficacy. We hypothesize that thrombus permeability estimated from radiological imaging is associated with improved recanalization after treatment with intravenously administered r-tPA (r-tPA) and with better functional outcome. METHODS: We assessed thrombus attenuation increase (TAI) in patients from the Dutch Acute Stroke Study with an occlusion of an intracranial artery on computed tomographic angiography. Patients were included within 9 hours after the stroke onset. After dichotomization of TAI as pervious or impervious, logistic regressions analyses were performed to estimate associations of intravenous r-tPA therapy with complete recanalization and with favorable functional outcome (modified Rankin Scale score of ≤2). RESULTS: Three hundred eight patients matched the inclusion criteria. The median TAI was 20.1 (interquartile range, 8.5-37.8) Hounsfield unit (HU). We found a significant increase in the odds of complete recanalization with increasing TAI for patients treated with intravenous r-tPA (P=0.030). One hundred thirty-one (42%) thrombi were classified as pervious with TAI of ≥23 HU. In patients with a pervious thrombus, complete recanalization was more frequent after treatment with intravenous r-tPA than after conservative treatment (odds ratio, 6.26; 95% confidence interval, 2.4-16.8; P<0.001). In patients with an impervious thrombus, the effect of intravenous r-tPA was not significant (odds ratio, 1.4; 95% confidence interval, 0.5-4.1; P=0.47). Favorable outcome was more common in patients with a pervious thrombi than without (odds ratio, 2.1; 95% confidence interval, 1.3-3.4; P=0.001). CONCLUSIONS: Thrombus perviousness, as measured on computed tomography in the acute stage of ischemic stroke, is strongly associated with recanalization after intravenous r-tPA treatment and with favorable functional outcome.