Reliability and accuracy of 3-mm and 2-mm maximum intensity projection CT angiography to detect intracranial large vessel occlusion in patients with acute anterior cerebral circulation stroke.

PURPOSE: To evaluate the reliability and accuracy of thick maximum intensity projection (MIP) CTA images to detect large-vessel occlusion (LVO) in the anterior circulation in patients with acute stroke. METHODS: A total of 140 acute stroke patients (41 with and 99 without LVO) were evaluated by two neuroradiologists for LVO using axial 3-mm and 2-mm MIPs. RESULTS: Interobserver agreement was substantial using 3-mm MIPs (ĸ = 0.67) and almost perfect using 2-mm MIPs (ĸ = 0.82). Using 3-mm MIPs, sensitivities were 80.5% and 68.3%, with specificities of 98.0% and 96.0%. Using 2-mm MIPs, sensitivities were 82.9% and 73.2%, with specificities of 98.0% and 99.0%. Sensitivity and specificity of 3 mm and 2 mm MIPs were not statistically significantly different (P ≥ 0.375). The majority of LVOs in the distal intracranial carotid artery, and/or M1-segment were correctly identified: 96.0% (observer 1, 3-mm MIPs), 88.0% (observer 2, 3-mm MIPs), 96.0% (observer 1, 2-mm MIPs), and 96.0% (observer 2, 2 mm MIPs). Using 3-mm MIP images, observers 1 and 2 missed 7/15 (46.7%) and 9/15 (60.0%) of isolated M2-segment occlusions, respectively. Using 2-mm MIP images, observers 1 and 2 missed 5/15 (33.3%) and 6/15 (40.0%) of isolated M2-segment occlusions, respectively. CONCLUSION: Thick (2-3 mm) axial MIPs are not useful to detect proximal LVO in the anterior circulation.

Radiology workload in clinical implementation of thrombectomy for acute ischemic stroke: experience from The Netherlands.

PURPOSE: To investigate the number of acute stroke patients undergoing CT angiography (CTA) for suspected large vessel occlusion (LVO) and those eligible for thrombectomy in relation to the population. METHODS: Consecutive patients in a Western population who underwent CTA for suspected LVO of the proximal anterior circulation between January and August 2019 were included. The date and time of CTA and the number of patients eligible for thrombectomy were assessed. Our hospital's service area population was estimated using the Central Bureau for Statistics data. One-way analysis of variance with post-hoc tests and chi-squared tests were used for statistical analyses. RESULTS: Of 520 patients (49% males, mean age of 72 years) undergoing CTA, 84 (16.2%) were eligible for thrombectomy. Our hospital's service area population was estimated at 420,000. Therefore, 3.6 CTA scans were performed and 0.6 patients were eligible for thrombectomy per 100,000 people per week. The number of patients undergoing CTA and the number of patients eligible for thrombectomy both did not significantly differ between any days of the week (P > 0.05). A total of 236 (45%) and 284 patients (55%) underwent CTA during office and on-call hours, respectively. The percentage of patients eligible for thrombectomy did not significantly differ between office and on-call hours (P = 0.834). CONCLUSION: Our study estimated the number of stroke patients undergoing CTA for suspected LVO and those eligible for thrombectomy in relation to the population. Numbers were essentially the same throughout the week, and during office and on-call hours. Our data can be used to make adequate staffing plans.

Treatment of thoracic or lumbar burst fractures with Balloon Assisted Endplate Reduction using Tricalcium Phosphate cement: histological and radiological evaluation.

BACKGROUND: Short-segment pedicle-screw instrumentation is frequently used to stabilize thoracolumbar burst fractures. A recognized disadvantage of this procedure is recurrent kyphosis from intervertebral disc creep into the fractured central endplate. Balloon Assisted Endplate Reduction (BAER) using Tricalcium Phosphate bone cement (TCP) enables elevation of the centrally depressed endplate. Our objective was to evaluate the bone-tissue response to TCP and to analyse whether BAER using TCP can prevent recurrent kyphosis after removal of the instrumentation. METHODS: Fourteen patients with traumatic thoracolumbar burst fractures were operated with BAER using TCP in combination with short-segment instrumentation. Nine months after surgery, instrumentation was removed and transpedicular biopsies were taken for histological and histochemical analysis. Roentgenograms pre- and postoperatively and at latest follow-up after removal of the instrumentation were evaluated. RESULTS: Average follow-up was 2.6 years. Analysis of the biopsies showed a variable degree of bone remodelling with incorporation of TCP into newly formed bone matrix. No extensive foreign body reactions, inflammation, granulomatous responses or tissue necrosis were observed. Wedge-angle, kyphosis-angle and both the anterior-posterior and central-posterior vertebral body height ratios improved significant postoperatively (p < 0.001). After removal of the instrumentation no significant differences in wedge-angle or height ratios were seen (p = 0.12). The kyphosis-angle increased four degrees (p = 0.01). CONCLUSION: TCP showed good histological osseointegration with no adverse events. TCP can therefore be safely used and could be beneficial in treatment of thoracolumbar burst fractures. BAER with TCP in combination with short-segment instrumentation might reduce recurrence of deformity even after removal of the instrumentation in comparison to short-segment instrumentation alone. TRIAL REGISTRATION: This study is registered at the at the Dutch Trial Registry (NTR3498).

Patient-specific positioning guides for total knee arthroplasty: no significant difference between final component alignment and pre-operative digital plan except for tibial rotation.

PURPOSE: To assess whether there is a significant difference between the alignment of the individual femoral and tibial components (in the frontal, sagittal and horizontal planes) as calculated pre-operatively (digital plan) and the actually achieved alignment in vivo obtained with the use of patient-specific positioning guides (PSPGs) for TKA. It was hypothesised that there would be no difference between post-op implant position and pre-op digital plan. METHODS: Twenty-six patients were included in this non-inferiority trial. Software permitted matching of the pre-operative MRI scan (and therefore calculated prosthesis position) to a pre-operative CT scan and then to a post-operative full-leg CT scan to determine deviations from pre-op planning in all three anatomical planes. RESULTS: For the femoral component, mean absolute deviations from planning were 1.8° (SD 1.3), 2.5° (SD 1.6) and 1.6° (SD 1.4) in the frontal, sagittal and transverse planes, respectively. For the tibial component, mean absolute deviations from planning were 1.7° (SD 1.2), 1.7° (SD 1.5) and 3.2° (SD 3.6) in the frontal, sagittal and transverse planes, respectively. Absolute mean deviation from planned mechanical axis was 1.9°. The a priori specified null hypothesis for equivalence testing: the difference from planning is >3 or <-3 was rejected for all comparisons except for the tibial transverse plane. CONCLUSION: PSPG was able to adequately reproduce the pre-op plan in all planes, except for the tibial rotation in the transverse plane. Possible explanations for outliers are discussed and highlight the importance for adequate training surgeons before they start using PSPG in their day-by-day practise. LEVEL OF EVIDENCE: Prospective cohort study, Level II.

Diagnostic performance of single-phase CT angiography in detecting large vessel occlusion in ischemic stroke: A systematic review.

PURPOSE: To systematically review the diagnostic performance of single-phase CT angiography (CTA) in detecting intracranial large vessel occlusion (LVO). METHOD: MEDLINE and Embase were searched for studies investigating the diagnostic performance of single-phase CTA in detecting LVO. Study quality was assessed. Sensitivity and specificity were calculated and meta-analyzed with a bivariate random-effects model. Heterogeneity was assessed with a chi-squared test. RESULTS: Eleven studies were included. High risk of bias with regard to "patient selection", "reference standard", and "flow and timing" was present in 4, 1, and 2 studies, respectively. In 7 studies, it was unclear whether reference tests were interpreted blinded to CTA readings. There was variability in types of vessel segments analyzed, resulting in heterogeneous sensitivity and specificity (P < 0.05). Two studies provided data for the proximal anterior circulation (distal intracranial carotid artery, A1-, A2-, M1- and M2-segments), with pooled sensitivity of 88.4 % (95 % CI: 62.2-97.2 %) and pooled specificity of 98.5 % (95 % CI: 33.2-100 %). One study suggested that multiphase CTA improved agreement between nonexperts and an expert in detecting A1-, A2-, M1-, M2-, and M3-segment occlusions compared to single-phase CTA (ĸ = 0.72-0.76 vs. ĸ = 0.32-0.45). No other included study reported added value of advanced CTA (CT perfusion, 4D-CTA, or multiphase CTA) compared to single-phase CTA in detecting proximal anterior circulation LVO. CONCLUSION: There is lack of high-quality studies on the diagnostic performance of single-phase CTA for LVO detection in the proximal anterior circulation. The added value of advanced CTA techniques in detecting proximal anterior circulation LVO is not completely clear yet.

MRI-Based Radiomics Analysis for the Pretreatment Prediction of Pathologic Complete Tumor Response to Neoadjuvant Systemic Therapy in Breast Cancer Patients: A Multicenter Study.

This retrospective study investigated the value of pretreatment contrast-enhanced Magnetic Resonance Imaging (MRI)-based radiomics for the prediction of pathologic complete tumor response to neoadjuvant systemic therapy in breast cancer patients. A total of 292 breast cancer patients, with 320 tumors, who were treated with neo-adjuvant systemic therapy and underwent a pretreatment MRI exam were enrolled. As the data were collected in two different hospitals with five different MRI scanners and varying acquisition protocols, three different strategies to split training and validation datasets were used. Radiomics, clinical, and combined models were developed using random forest classifiers in each strategy. The analysis of radiomics features had no added value in predicting pathologic complete tumor response to neoadjuvant systemic therapy in breast cancer patients compared with the clinical models, nor did the combined models perform significantly better than the clinical models. Further, the radiomics features selected for the models and their performance differed with and within the different strategies. Due to previous and current work, we tentatively attribute the lack of improvement in clinical models following the addition of radiomics to the effects of variations in acquisition and reconstruction parameters. The lack of reproducibility data (i.e., test-retest or similar) meant that this effect could not be analyzed. These results indicate the need for reproducibility studies to preselect reproducible features in order to properly assess the potential of radiomics.

Assessment of the collateral function of the circle of Willis: three-dimensional time-of-flight MR angiography compared with transcranial color-coded duplex sonography.

BACKGROUND AND PURPOSE: Identification of the intracranial collaterals assists in identifying patients with severe occlusive disease of the internal carotid arteries who are at lower risk of transient ischemic attacks (TIAs) and stroke. We investigated the usefulness of MR angiography in identifying functional collaterals of the circle of Willis. METHODS: MR angiography of the circle of Willis was performed in 50 healthy volunteers. Visibility was used as the criterion to define the intracranial collaterals as being functional. Two observers independently assessed the MR angiograms. Results were compared with those of transcranial color duplex sonography (TCCD), and results of carotid compression tests were the standard of reference for the identification of functional intracranial collaterals. RESULTS: With MR angiograms, reviewer 1 achieved a sensitivity of 85%, a specificity of 81%, a positive predictive value of 95%, and a negative predictive value of 55%. Reviewer 2 achieved a sensitivity of 87%, a specificity of 67%, a positive predictive value of 92%, and a negative predictive value of 53%. Interobserver agreement on MR angiograms was moderate (kappa = 0.57, 95% confidence interval: 0.42, 0.72). CONCLUSION: Visible collaterals of the circle of Willis on MR angiograms are able to supply collateral flow in the presence of carotid artery obstruction. However, the low negative predictive value of MR angiography indicates that, if collaterals are not visible, supplementary TCCD investigation is required.

The use of CT-angiography for monitoring thrombus formation after balloon occlusion of a dissecting vertebral artery pseudoaneurysm.

We present a 49-year-old man with a subarachnoid haemorrhage from a dissecting vertebral artery (VA) pseudoaneurysm treated with a proximal balloon occlusion. The clinical course was complicated by the sudden appearance of a lateral medullary syndrome (Wallenberg), which completely resolved after anticoagulant therapy. During this course, CT-angiography (CTA) enabled monitoring of both the progression and partial resolution of the thrombus in the occluded VA. An anatomical variant of a perforating artery originating from the VA proximal to the posterior inferior cerebral artery (PICA) was subsequently demonstrated, explaining the ischemic event. The value of CTA in clinical management is discussed. The prophylactic use of anticoagulant therapy especially in the case of a perforating artery to the lateral medulla originating proximally to the PICA, is suggested.