Narrative review of the utility of magnetic resonance imaging in radiotherapy for cervical cancer.

BACKGROUND AND OBJECTIVE: In radiotherapy (RT) for locally advanced cervical cancer, high soft tissue contrast on magnetic resonance imaging (MRI) can ensure accurate delineation of target volumes (TVs) and optimal dose distribution to the RT target and organs at risk (OAR). MRI-guided adaptive RT (MRIgART) is a novel technology that revises RT plans according to anatomical changes occurring throughout the treatment to improve target coverage and minimise OAR toxicity. This review aims to assess the evidence and gaps of MRI use in RT planning and MRIgART in the treatment of cervical cancer, as well as challenges in its clinical implementation. METHODS: Ovid Medline and PubMed were searched using keywords for MRI in RT for cervical cancer. After applying the inclusion and exclusion criteria, the initial search was deduced to 32 studies. A total of 37 final studies were reviewed, including eight additional articles from references. KEY CONTENT AND FINDINGS: In the primary studies, TVs and organ motion were assessed before, during, and after treatment. MRI was used to investigate dose distribution and therapeutic response to the treatment in association with its outcome. Lastly, rationales for MRIgART were evaluated. CONCLUSIONS: It was concluded that MRI enables accurate target delineation, assessment of organ motion and interfraction changes, and monitoring of treatment response through dynamic parameters. Enhanced target coverage and reduced OAR irradiation through MRIgART can improve local control and the overall outcome, although its rationales against the logistical challenges need to be evaluated on further research.

Subsegmental pulmonary embolism and anticoagulant therapy: the impact of clinical context.

BACKGROUND: Anticoagulation for subsegmental pulmonary embolism (SSPE) is controversial. AIM: To assess the impact of clinical context on anticoagulation and outcomes of SSPE. METHODS: We electronically searched computed tomography pulmonary angiogram reports to identify SSPE. We extracted demographic, risk factor, investigations and outcome data from the electronic medical record. We stratified patients according to anticoagulation and no anticoagulation. RESULTS: From 1 January 2017 to 31 December 2019, we identified 166 patients with SSPE in 5827 pulmonary angiogram reports. Of these, 123 (74%) received anticoagulation. Compared with non-anticoagulated patients, such patients had a different clinical context: higher rates of previous venous thromboembolism (11% vs 0%; P = 0.019), more recent surgery (26% vs 9%; P = 0.015), more elevated serum D-dimer (22% vs 5%; P = 0.004), more lung parenchymal abnormalities (76% vs 61%; P = 0.037) and were almost twice as likely to require inpatient care (76% vs 42%; P < 0.001). Such patients also had twice the all-cause mortality at 1 year (32% vs 16%). CONCLUSIONS: SSPE is diagnosed in almost 3% of pulmonary angiograms and is associated with high mortality, regardless of anticoagulation, due to coexistent disease processes rather than SSPE. Anticoagulation appears dominant but markedly affected by the clinical context of risk factors, alternative indications and illness severity. Thus, the controversy is partly artificial because anticoagulation after SSPE is clinically contextual with SSPE as only one of several factors.

Preoperative Imaging in Patients with Deep Infiltrating Endometriosis: An Important Aid in Predicting Depth of Infiltration in Rectosigmoid Disease.

STUDY OBJECTIVE: To determine the diagnostic accuracy of specialist-performed transvaginal ultrasound (TVUS) and pelvic magnetic resonance imaging (MRI) modalities in predicting depth of deep infiltrating endometriosis (DIE) of the rectosigmoid by comparison with histologic specimens obtained at surgery. DESIGN: A retrospective analysis, which met the Standards for Reporting of Diagnostic Accuracy Studies (2015) guidelines for a diagnostic accuracy study. SETTING: Tertiary teaching hospital. PATIENTS: A total of 194 cases who underwent preoperative discussion at the gynecologic endosurgery unit multidisciplinary meeting between January 2012 and December 2019 were eligible for inclusion. INTERVENTIONS: Retrospective assessment of the accuracy of TVUS and MRI in predicting histologic depth of rectosigmoid DIE after operative management. MEASUREMENTS AND MAIN RESULTS: Al total of 135 surgeries were performed for DIE; 20 underwent a rectal shave, 14 had a disc/wedge resection, 38 an anterior/segmental resection, and 63 had no rectosigmoid surgery. Of the 52 patients with full-thickness rectal wall excision, all patients had at least one imaging modality available for review; 42 (81%) had both. At least one imaging modality was in agreement with histologic depth in 48 cases (92%) (sensitivity, 94%; specificity, 50%; positive predictive value [PPV], 97.9%; negative predictive value [NPV], 25.0%; area under the receiver operating curve, 0.720; 95% confidence interval, 0.229-1.000). When TVUS was assessed in isolation, the test remained sensitive for any rectal wall involvement (sensitivity, 93.6%; specificity, 50.0%; PPV, 97.8%; NPV, 25.0%; area under the receiver operating curve, 0.718; 95% confidence interval, 0.227-1.000). When only MRI was assessed, the test demonstrated both high sensitivity and specificity for rectal wall disease (sensitivity, 86.4%; specificity, 100%; PPV, 100%; NPV, 14.2). CONCLUSION: Specialist-performed TVUS and MRI are accurate in predicting depth of disease in rectosigmoid endometriosis. These modalities were similar in their diagnostic performance at assessing depth of rectal wall involvement, and their use is justified in the preoperative planning of these gynecologic surgeries.

Deep infiltrating endometriosis: Can magnetic resonance imaging anticipate the need for colorectal surgeon intervention?

OBJECTIVE: To identify magnetic resonance imaging (MRI) features associated with colorectal surgical bowel resection for treatment of deep infiltrating endometriosis (DIE). MATERIALS AND METHODS: 122 preoperative pelvic MRIs in women with laparoscopically-proven DIE and subsequent surgery (2006-2015) were identified, and retrospective cohort analysis performed. MRIs were reviewed independently by two radiologists blinded to surgical/histopathological outcomes. Associations between MRI characteristics of middle/posterior compartment endometriosis and surgical outcomes were investigated to identify MRI features associated with colorectal surgical bowel resection. RESULTS: MRI features associated with colorectal surgical intervention were: presence of an MRI bowel lesion (sensitivity 95.3%, specificity 63.3%, ROC-AUC 0.79); MRI bowel lesions ≥20 mm in length (sensitivity 91%, specificity 77%, ROC-AUC 0.84); MRI bowel lesions invading the muscularis or submucosa/mucosa layers (sensitivity 95.3%, specificity 63.3%, ROC-AUC 0.90). CONCLUSION: This study identifies MRI features that have potential diagnostic utility in identifying the need for colorectal surgical intervention in patients with DIE.

Invisible cortex sign: A highly accurate feature to localize the inferolateral central sulcus.

INTRODUCTION: The central sulcus is a key landmark on MRI of the brain, but its inferolateral portion is difficult to identify if unable to trace the sulcus superoinferiorly. The authors observed that the cortex abutting the central sulcus appears isointense to the adjacent white matter on DWI, we named this the 'invisible cortex sign' and our study evaluates whether it could be used to identify the inferolateral central sulcus. METHODS: Observational study of 108 consecutive 'normal' MRI studies performed from May 2016 to January 2017. A single axial DWI image - obtained in the anterior commissure-posterior commissure plane - was selected from each scan just above the subcentral gyrus such that it included the most inferolateral portion of the central sulcus. These single images were given to 10 readers (neuroradiologists, a neuroradiology fellow and radiology trainees) who marked the central sulcus based on the presence of the 'invisible cortex sign'. Their accuracy in identifying the central sulcus was compared with that of the principal investigators, who used tri-planar T1 volumetric MRI sequences. RESULTS: One hundred and eight consecutive patients (55 female, 53 male) were selected, ranging from 18 to 81 years old (mean = 40.5, σ = 18.2). The central sulcus was correctly identified in 95.5% of cases (σ = 3.7%; range 89.4-99.1%). CONCLUSION: The 'invisible cortex sign' is a highly accurate method of identifying the inferolateral central sulcus on a single axial DWI slice without relying on the more superior aspects of the sulcus.

Magnetic resonance imaging features of gemistocytic astrocytoma.

INTRODUCTION: Gemistocytic astrocytoma is the second most common subtype of World Health Organization grade 2 astrocytoma, but has a worse prognosis than other grade 2 lesions. We aim to describe the MR imaging features of histopathologically proven gemistocytic tumours. METHODS: Ethics approval was obtained from both institutions. Patient consent was not required for this retrospective study. We reviewed MR imaging findings of 16 consecutive cases of histopathologically proven gemistocytic astrocytoma and anaplastic astrocytoma with gemistocytic features. RESULTS: Average patient age was 48 years, with a 3:1 male to female ratio. Based on our series, the typical appearance of a gemistocytic astrocytoma is a large, heterogeneous mass most commonly supratentorial and lobar. Regions of cyst formation, partial signal suppression on FLAIR images and contrast enhancement are all common features. Additionally, contrary to previous literature that describes gemistocytic astrocytoma as a purely supratentorial lesion, we present two cases of gemistocytic astrocytoma involving the brainstem. CONCLUSIONS: The possibility of gemistocytic astrocytoma should be considered in patients presenting with large heterogeneous tumours that have regions of cyst formation, partial FLAIR suppression and contrast enhancement. This may be especially useful in reconciling a lesion with high-grade MR imaging features with low-grade histopathology. An infratentorial location does not preclude the diagnosis of gemistocytic astrocytoma.

Diffusion-weighted imaging properties of uterine fibroids pre- and post-uterine fibroid embolisation.

OBJECTIVE: To determine the change in apparent diffusion coefficient (ADC) of uterine fibroids following uterine fibroid embolisation (UFE), and if the ADC change correlates with either volume loss or degree of contrast enhancement post-UFE. MATERIALS AND METHODS: This study was approved by our institutional review board with waiver of consent. The pelvic MRI examinations, including diffusion-weighted MRI (DWI) using 4 b-values, of 50 consecutive patients prior to and 6 months post-UFE were analyzed. The volume, ADC and amount of enhancement were calculated for each fibroid both pre- and post-UFE. The percent residual enhancement for each fibroid was categorized as either: no (0-1%) residual enhancement or residual (>1%) enhancement. Statistical analysis compared ADC, enhancement and volume for each fibroid pre- and post-UFE using paired t-tests and Pearson correlation coefficients. RESULTS: The mean ADC of all (n=88) fibroids pre-UFE was 1.30±0.20×10(-3)mm(2)/s, and increased to 1.68±0.24×10(-3)mm(2)/s post-UFE (p<0.0001). Lower pre-UFE ADC correlated with greater ADC change post-UFE (r=-0.50; p<0.0001). There was no correlation between ADC change and volume change post-UFE (r=0.07; p=0.59). However, fibroids with no residual enhancement post-UFE had larger ADC change than those with residual enhancement (p=0.003). CONCLUSION: The ADC of fibroids rises post-UFE. ADC change post-UFE is associated with the degree of loss of enhancement and may therefore be valuable in predicting response to treatment in pre-procedural counseling.

The augmented breast: a pictorial review of the abnormal and unusual.

OBJECTIVE: This article reviews the multimodality imaging features of breast augmentation complications as well as appearances of unusual breast augmentation techniques. CONCLUSION: Cosmetic breast augmentation is an increasingly common procedure performed in our society. Although breast prosthesis implantation is the most common technique, other unusual techniques such as autologous fat implantation as well as direct liquid silicone and paraffin injections have also been used.