Rapid non-contrast magnetic resonance imaging for post appendectomy intra-abdominal abscess in children.

BACKGROUND: Acute appendicitis, especially if perforated at presentation, is often complicated by postoperative abscess formation. The detection of a postoperative abscess relies primarily on imaging. This has traditionally been done with contrast-enhanced computed tomography. Non-contrast magnetic resonance imaging (MRI) has the potential to accurately detect intra-abdominal abscesses, especially with the use of diffusion-weighted imaging (DWI). OBJECTIVE: To evaluate our single-center experience with a rapid non-contrast MRI protocol evaluating post-appendectomy abscesses in children with persistent postsurgical symptoms. MATERIALS AND METHODS: In this retrospective, institutional review board-approved study, all patients underwent a clinically indicated non-contrast 1.5- or 3-Tesla abdomen/pelvis MRI consisting of single-shot fast spin echo, inversion recovery and DWI sequences. All MRI studies were reviewed by two blinded pediatric radiologists to identify the presence of a drainable fluid collection. Each fluid collection was further characterized as accessible or not accessible for percutaneous or transrectal drainage. Imaging findings were compared to clinical outcome. RESULTS: Seven of the 15 patients had a clinically significant fluid collection, and 5 of these patients were treated with percutaneous drain placement or exploratory laparotomy. The other patients had a phlegmon or a clinically insignificant fluid collection and were discharged home within 48 h. CONCLUSION: Rapid non-contrast MRI utilizing fluid-sensitive and DWI sequences can be used to identify drainable fluid collections in post-appendectomy patients. This protocol can be used to triage patients between conservative management vs. abscess drainage without oral/intravenous contrast or exposure to ionizing radiation.

Interobserver reliability for computed tomography findings of adnexal torsion.

Pelvic pain is a common presenting symptom in the emergency room, and prompt diagnosis of adnexal torsion is essential to reduce the risk of irreversible ovarian ischemia. Although ultrasound has been the study of choice for the diagnosis of adnexal torsion, patients with pelvic pain may often be imaged first with computed tomography given the prevalent use of computed tomography in the emergency department. Therefore, it is essential to be familiar with the computed tomography signs of adnexal torsion. A retrospective study of 40 patients with adnexal torsion with and without an adnexal mass was conducted to evaluate interobserver reliability for the computed tomography signs of adnexal torsion. With the exception of deviation of the uterus to the twisted side, interobserver reliability was fair for all computed tomography signs of adnexal torsion. There was no difference in interobserver reliability for most signs between patients with a mass and those without. However, for a twisted vascular pedicle, there was moderate agreement in patients with a mass and no agreement for patients without a mass. Although many computed tomography signs of adnexal torsion have been described, interobserver reliability for most of these signs was found to be fair.

Unsuspected COVID-19 pneumonia suggests need for higher level of personal protective equipment usage during routine radiologic examinations: Two case reports.

Two case reports demonstrating the need for enhanced usage of personal protective equipment of face shield, respirator, gloves, and gown during routine radiologic evaluation who may screen negative for COVID-19 and or atypical COVID-19 symptoms. First case is of a 42-year-old woman undergoing preoperative evaluation for endometrial cancer in the outpatient setting. The second case is of a 49-year-old woman presenting with abdominal pain, nausea, and vomiting for abdominal CT imaging from the emergency department. Both cases demonstrate typical lung imaging finding of COVID-19. These cases highlight the need for additional precautions in the outpatient and emergency setting even for patients in whom COVID-19 infection is not suspected.

MDCT angiography of emergent, non-traumatic, upper extremity vascular lesions.

Timely, accurate diagnosis of upper extremity vascular pathology is critical for successful clinical and surgical management. Although the vast majority of upper extremity vascular injury is due to trauma, physicians in the emergency setting, including radiologists, must be familiar with vascular lesions from iatrogenic injury, thromboembolic disease, vascular malformations, and vasculitis. Non-invasive diagnostic imaging with multidetector CT (MDCT) angiography is often employed in the emergency department to evaluate patients with suspected vascular pathology of the upper extremity. Maximum intensity projection and volume rendering technique are two methods that are useful for evaluating vasculature. In addition, dual-energy MDCT is useful in that it allows for the generation of iodine-selective images and bone subtracted images. These techniques can be used to create images that simulate catheter angiograms. In this article, we will discuss the role of MDCT angiography in the diagnosis and management of emergent non-traumatic vascular lesions of the upper extremity.

Clinical time course and CT detection of metastatic disease to the small bowel.

PURPOSE: The purpose of this study was to identify the CT characteristics of metastatic disease of the small bowel and define the clinical time course between primary tumor diagnosis and small bowel metastasis detection. METHODS: A retrospective search of a pathologic database for metastases to small bowel identified 242 cases. Exclusion criteria were cases without CT (N = 49), serosal or mesenteric metastases (N = 114), or cases of direct invasion to small bowel (N = 63). The clinical records and imaging were reviewed for 16 patients. RESULTS: Melanoma was the most common malignancy to metastasize to small bowel (7 of 16 patients). Only one of the 16 cases was detected at the time of initial diagnosis of their primary malignancy. The average time from diagnosis of the primary malignancy or remission to the time of detection of the small bowel metastasis was 7.2 and 8.3 years, respectively. The most common symptoms were gastrointestinal bleeding (N = 5) and small bowel obstruction (N = 5). In 3 cases, the masses were not identified on pre-operative CT. CONCLUSION: Metastases to the small bowel often occur many years after the initial diagnosis of the primary malignancy or entering remission and may be symptomatic. Attention to the small bowel is particularly important in melanoma patients, who may have multiple small bowel metastases, even after many years of being disease free. As oncology patients undergo numerous surveillance scans and improved therapies allow for longer survival, detection of these masses at a small size can facilitate elective resection to avert urgent surgical intervention.

Clinical Resting-state fMRI in the Preoperative Setting: Are We Ready for Prime Time?

The purpose of this manuscript is to provide an introduction to resting-state functional magnetic resonance imaging (RS-fMRI) and to review the current application of this new and powerful technique in the preoperative setting using our institute's extensive experience. RS-fMRI has provided important insights into brain physiology and is an increasingly important tool in the clinical setting. As opposed to task-based functional MRI wherein the subject performs a task while being scanned, RS-fMRI evaluates low-frequency fluctuations in the blood oxygen level dependent (BOLD) signal while the subject is at rest. Multiple resting state networks (RSNs) have been identified, including the somatosensory, language, and visual networks, which are of primary importance for presurgical planning. Over the past 4 years, we have performed over 300 RS-fMRI examinations in the clinical setting and these have been used to localize eloquent somatosensory and language cortices before brain tumor resection. RS-fMRI is particularly useful in this setting for patients who are unable to cooperate with the task-based paradigm, such as young children or those who are sedated, paretic, or aphasic.Although RS-fMRI is still investigational, our experience indicates that this method is ready for clinical application in the presurgical setting.

Clustering of resting state networks.

BACKGROUND: The goal of the study was to demonstrate a hierarchical structure of resting state activity in the healthy brain using a data-driven clustering algorithm. METHODOLOGY/PRINCIPAL FINDINGS: The fuzzy-c-means clustering algorithm was applied to resting state fMRI data in cortical and subcortical gray matter from two groups acquired separately, one of 17 healthy individuals and the second of 21 healthy individuals. Different numbers of clusters and different starting conditions were used. A cluster dispersion measure determined the optimal numbers of clusters. An inner product metric provided a measure of similarity between different clusters. The two cluster result found the task-negative and task-positive systems. The cluster dispersion measure was minimized with seven and eleven clusters. Each of the clusters in the seven and eleven cluster result was associated with either the task-negative or task-positive system. Applying the algorithm to find seven clusters recovered previously described resting state networks, including the default mode network, frontoparietal control network, ventral and dorsal attention networks, somatomotor, visual, and language networks. The language and ventral attention networks had significant subcortical involvement. This parcellation was consistently found in a large majority of algorithm runs under different conditions and was robust to different methods of initialization. CONCLUSIONS/SIGNIFICANCE: The clustering of resting state activity using different optimal numbers of clusters identified resting state networks comparable to previously obtained results. This work reinforces the observation that resting state networks are hierarchically organized.

Functional connectivity during modulation of tinnitus with orofacial maneuvers.

OBJECTIVE: To determine changes in cortical neural networks as defined by resting-state functional connectivity magnetic resonance imaging during voluntary modulation of tinnitus with orofacial maneuvers. STUDY DESIGN: Cross-sectional study. SETTING: Academic medical center. SUBJECTS AND METHODS: Participants were scanned during the maneuver and also at baseline to serve as their own control. The authors chose, a priori, 58 seed regions to evaluate previously described cortical neural networks by computing temporal correlations between all seed region pairs. Seed regions whose correlations significantly differed between rest and maneuver (P < .05, uncorrected) entered into a second-stage analysis of computing the correlation coefficient between the seed region and time courses in each of the remaining brain voxels. A threshold-free cluster enhancement permutation analysis evaluated the distribution of these correlation coefficients after transformation to Fisher z scores and registration to a surface-based reconstruction using Freesurfer. RESULTS: The median age for the 16 subjects was 54 years (range, 27-72 years), and all had subjective, unilateral or bilateral, nonpulsatile tinnitus for 6 months or longer. In 9 subjects who could voluntarily increase the loudness of their tinnitus, there were no significant differences in functional connectivity in any cortical networks. A separate analysis evaluated results from 3 patients who decreased the loudness of their tinnitus. Four subjects were excluded because of excessive motion in the scanner. CONCLUSION: The absence of significant differences in functional connectivity due to voluntary orofacial maneuvers that increased tinnitus loudness failed to confirm prior reports of altered cerebral blood flows during somatomotor behaviors.