Voxel level dense prediction of acute stroke territory in DWI using deep learning segmentation models and image enhancement strategies.

PURPOSE: To build a stroke territory classifier model in DWI by designing the problem as a multiclass segmentation task by defining each stroke territory as distinct segmentation targets and leveraging the guidance of voxel wise dense predictions. MATERIALS AND METHODS: Retrospective analysis of DWI images of 218 consecutive acute anterior or posterior ischemic stroke patients examined between January 2017 to April 2020 in a single center was carried out. Each stroke area was defined as distinct segmentation target with different class labels. U-Net based network was trained followed by majority voting of the voxel wise predictions of the model to transform them into patient level stroke territory classes. Effects of bias field correction and registration to a common space were explored. RESULTS: Of the 218 patients included in this study, 141 (65%) were anterior stroke, and 77 were posterior stroke (35%) whereas 117 (53%) were male and 101 (47%) were female. The model built with original images reached 0.77 accuracy, while the model built with N4 bias corrected images reached 0.80 and the model built with images which were N4 bias corrected and then registered into a common space reached 0.83 accuracy values. CONCLUSION: Voxel wise dense prediction coupled with bias field correction to eliminate artificial signal increase and registration to a common space help models for better performance than using original images. Knowing the properties of target domain while designing deep learning models is important for the overall success of these models.

Comparison of ASL and DSC perfusion methods in the evaluation of response to treatment in patients with a history of treatment for malignant brain tumor.

OBJECTIVE: Perfusion MRI is of great benefit in the post-treatment evaluation of brain tumors. Interestingly, dynamic susceptibility contrast-enhanced (DSC) perfusion has taken its place in routine examination for this purpose. The use of arterial spin labeling (ASL), a perfusion technique that does not require exogenous contrast material injection, has gained popularity in recent years. The aim of the study was to compare two different perfusion techniques, ASL and DSC, using qualitative and quantitative measurements and to investigate the diagnostic effectiveness of both. The fact that the number of patients is higher than in studies conducted with 3D pseudo-continious ASL (pCASL), the study group is heterogeneous as it consists of patients with both metastases and glial tumors, the use of 3D Turbo Gradient Spin Echo (TGSE), and the inclusion of visual (qualitative) assessment make our study unique. METHODS: Ninety patients, who were treated for malignant brain tumor, were enrolled in the retrospective study. DSC Cerebral Blood Volume (CBV), Cerebral Blood Flow (CBF) and ASL CBF maps of each case were obtained. In qualitative analysis, the lesions of the cases were visually classified as treatment-related changes (TRC) and relapse/residual mass (RRT). In the quantitative analysis, three regions of interest (ROI) measurements were taken from each case. The average of these measurements was compared with the ROI taken from the contralateral white matter and normalized values (n) were obtained. These normalized values were compared across events. RESULTS: Uncorrected DSC normalized CBV (nCBV), DSC normalized CBF (nCBF) and ASL nCBF values of RRT cases were higher than those of TRC cases (p < 0.001). DSC nCBV values were correlated with DSC nCBF (r: 0.94, p < 0.001) and correlated with ASL nCBF (r: 0.75, p < 0.001). Similarly, ASL nCBF was positively correlated with DSC nCBF (r: 0.79 p < 0.01). When the ROC curve parameters were evaluated, the cut-off values were determined as 1.211 for DSC nCBV (AUC: 0.95, 93% sensitivity, 82% specificity), 0.896 for DSC nCBF (AUC; 0.95, 93% sensitivity, 82% specificity), and 0.829 for ASL nCBF (AUC: 0.84, 78% sensitivity, 75% specificity). For qualitative evaluation (visual evaluation), inter-observer agreement was found to be good for ASL CBF (0.714), good for DSC CBF (0.790), and excellent for DSC CBV (0.822). Intra-observer agreement was also evaluated. For the first observer, good agreement was found in ASL CBF (0.626, 70% sensitive, 93% specific), in DSC CBF (0.713, 76% sensitive, 95% specific), and in DSC CBV (0.755, 87% sensitive - 88% specific). In the second observer, moderate agreement was found in ASL CBF (0.584, 61% sensitive, 97% specific) and DSC CBF (0.649, 65% sensitive, 100% specific), and excellent agreement in DSC CBV (0.800, 89% sensitive, 90% specific). CONCLUSION: It was observed that uncorrected DSC nCBV, DSC nCBF and ASL nCBF values were well correlated with each other. In qualitative evaluation, inter-observer and intra-observer agreement was higher in DSC CBV than DSC CBF and ASL CBF. In addition, DSC CBV is found more sensitive, ASL CBF and DSC CBF are found more specific for both observers. From a diagnostic perspective, all three parameters DSC CBV, DSC CBF and ASL CBF can be used, but it was observed that the highest rate belonged to DSC CBV.

Is Balloon Kyphoplasty Effective for Bone Remodeling of AO-Type A3-4 Fractures at the Thoracolumbar Junction?

AIM: Vertebral compression fractures (VCF) occur most commonly at the thoracolumbar junction (TLJ). Balloon kyphoplasty (BKP) is an effective method of bone remodeling in these cases. In this study, we evaluate the parameters that affect bone retropulsion and restoration in TLJ VCF without neurological deficits. MATERIAL AND METHODS: Thirty-one of Frankel E and AO A3-4 type VCFs fractures at the TLJ, with bone retropulsion into the spinal canal, from 2017 to 2020, were evaluated retrospectively. Data was gathered on patient demographics and medical histories. Measurements of anterior vertebral heights, posterior vertebral heights, local kyphotic angles, spinal cord area, and bone retropulsion into the spinal canal (BRC) were evaluated preoperatively, early postoperatively, and late postoperatively. RESULTS: In those patients who underwent early surgery ( 4 weeks postfracture), a significantly greater increase in anterior vertebral heights was seen between early postoperative and preoperative measurements than in patients who underwent late surgery ( 4 weeks postfracture) (p = 0.016). At the six-month follow-up, a significantly greater decrease in local kyphotic angle measurements was seen in patients over 65 years of age than those under 65 (p = 0.023). Comparison of local kyphotic angles between sexes revealed a significant decrease in measurements at follow-up in female patients (p = 0.029). Both early postoperative and late postoperative local kyphotic angle measurements of patients with a body mass index (BMI) ≥25 were significantly lower than those of patients with a BMI 25 (p = 0.012). CONCLUSION: The restoration of vertebral angles and heights with the maximum level of BKP can effectively reduce BRC.

Investigation of ligament, bone, synovial and plica pathologies accompanied by common extensor tendon in patients with lateral overuse syndrome of the elbow using magnetic resonance imaging.

BACKGROUND: Tendinosis in the common extensor tendon and accompanying ligament, bone, and plica abnormalities can be observed on magnetic resonance imaging (MRI). PURPOSE: To determine whether there is a difference between accompanying abnormalities according to the degree of common extensor tendon injury. MATERIAL AND METHODS: Patients who underwent 1.5-T MRI tests with a prediagnosis of lateral overuse syndrome were retrospectively reviewed, and 56 patients who had an injury in the common extensor tendon (CET) were included. The degree of tendon and ligament injury, muscle signal change, bone marrow signal change, presence of joint effusion, and morphological features in the presence of plica were evaluated via MRI examinations of the elbow. RESULTS: Overall, 32, 16, and eight patients had mild, moderate, and severe CET damage, respectively. As the severity of CET damage increased, the presence of joint effusion, and the presence and degree of damage to the lateral ulnar collateral ligament (LUCL) and radial collateral ligament (RCL) increased. The radiohumeral (RH) plica area was significantly larger in the group with mild CET damage. There was no statistically significant correlation between the severity of CET damage and the end of RH plica with a blind-end, coverage of one-third or more of the radius, its signal, thickness, and presence of olecranon fold. CONCLUSION: As the severity of CET injury increases, damage to the LUCL, RCL, and the presence of effusion in the joint increases. RH plica should be evaluated in terms of concomitant pathology in patients with mild CET injuries on MRI.

Detection and vascular territorial classification of stroke on diffusion-weighted MRI by deep learning.

PURPOSE: Rapid detection and vascular territorial classification of stroke enable the determination of the most appropriate treatment. In this study, we aimed to investigate the performance of convolutional neural network (CNN) models in the detection and vascular territorial classification of stroke on diffusion-weighted images (DWI). METHODS: DWI of 421 cases (271 acute ischemic stroke patients and 150 cases without any ischemia findings on DWI) obtained between January 2017 to April 2020 were reviewed. We created two custom datasets. A stroke detection dataset was created with 1800 slices (900 S and 900 normal) consisting of 1400 for training, 200 for validation, 200 for test. A vascular territorial type dataset was created with 1717 slices (883 middle cerebral artery stroke, 416 posterior circulatory stroke, and 418 watershed stroke) consisting of 1117 slices for training, 300 for validation, 300 for test. A transfer learning approach based on MobileNetV2 and EfficientNet-B0 CNN architecture was used. The performance of the models was evaluated. RESULTS: Modified MobileNetV2 and EfficientNet-B0 models achieved 96% (κ: 0.92) and 93% (κ: 0.86) accuracy in stroke detection, respectively. In vascular territorial classification of stroke as middle cerebral artery, posterior circulation, or watershed infarction, an accuracy of 93% (κ: 0.895) was achieved with modified MobileNetV2 model and 87% (κ: 0.805) with modified EfficientNet-B0 CNN model. CONCLUSION: Transfer learning approach with custom top CNN models achieve sufficiently high performance for both the detection of ischemic stroke and the classification of its vascular territorial type on DWI.

The relationship between patellar tilt and quadriceps patellar tendon angle with anatomical variations and pathologies of the knee joint.

PURPOSE: To investigate the association between the knee joint anatomical variations and pathologies, and to describe the quadriceps patellar tendon angle (QPA). METHODS: MRIs of 406 cases with a lateral patellar tilt angle (LPT)>5° and a control group of 40 cases with an LPT<5° were retrospectively evaluated. QPA, LPT, trochlear sulcus angle (TSA), tibial tubercle-trochlear groove distance (TT-TG), Insall-Salvati index (ISI), patellar tendon length (PTL), patellar height (PH), lateral trochlear inclination (LTI), trochlear facet asymmetry ratio (TFA) and trochlear depth (TD) were measured. Presence of fat-pad oedema, patellar and trochlear chondromalacia, patellar and quadriceps tendinosis and effusion were evaluated. RESULTS: The medians of TSA, PTL, ISI and TT-TG were significantly higher; LTI, TFA and TD were significantly lower in the patient group. The prevalence of SL-Hoffa, non-SL-Hoffa, suprapatellar and prefemoral fat-pad oedema, effusion and chondromalacia were significantly higher in the patient group. LPT was found to be positively correlated with TSA and TT-TG, and negatively correlated with LTI and TD. Cases with trochlear dysplasia, patellar chondromalacia and quadriceps tendinosis had significantly higher LPT. There was a positive correlation between QPA and TSA and a negative correlation between QPA and LTI. Cases with trochlear dysplasia, non-SL-Hoffa oedema, prefemoral fat-pad oedema and quadriceps tendinosis had significantly higher QPA. We found 10°

Torsion of Wandering Spleen: Importance of Splenic Density and Liver-to- Spleen Attenuation Ratio on CT.

BACKGROUND: Wandering spleen (WS) is a rare clinical condition which may cause fatal complication like torsion with subsequent infarction. Determination of splenic parenchyma viability is very important in deciding whether splenopexy rather than splenectomy is an option. Contrast- enhanced computed tomography (CECT) is important for the diagnosis of WS and assessment of the viability of spleen. DISCUSSION: We reviewed the CT studies of four cases with WS. We measured the mean splenic and liver density and calculated liver-to-spleen attenuation ratio (LSAR). We also assessed the CT findings for each patient. Mean splenic density was measured as 40.77 Hounsfield Unit (HU) in cases with infarction, 127.1 HU in case without infarction. LSAR was calculated as 2.55 in cases with infarction, 0.99 in case without infarction. We detected whirlpool sign, intraperitoneal free fluid, splenic arterial enhancement in all patient, parenchymal and splenic vein enhancement in one patient without infarction, fat rim sign in three patients with infarction, capsular rim sign in one patient with infarction. CONCLUSION: CECT should be obtained for the diagnosis of WS and assessment of the viability of spleen. CECT could suggest the diagnosis of infarction of the spleen with following findings; absence of parenchymal enhancement, very low density of spleen (<45 HU), and LSAR which is greater than 2.