Kevin S. Baker

Necrotizing fasciitis and its mimics: what radiologists need to know.

OBJECTIVE The purpose of this article is to review the imaging features of necrotizing fasciitis and its potential mimics. Key imaging features are emphasized to enable accurate and efficient interpretation of variables that are essential in appropriate management. CONCLUSION Necrotizing fasciitis is a medical emergency with potential lethal outcome. Dissecting gas along fascial planes in the absence of penetrating trauma (including iatrogenic) is essentially pathognomonic. However, the lack of soft-tissue emphysema does not exclude the diagnosis. Mimics of necrotizing fasciitis include nonnecrotizing fasciitis (eosinophilic, paraneoplastic, inflammatory (lupus myofasciitis, Churg-Strauss, nodular, or proliferative), myositis, neoplasm, myonecrosis, inflammatory myopathy, and compartment syndrome. Necrotizing fasciitis is a clinical diagnosis, and imaging can reveal nonspecific or negative findings (particularly during the early course of disease). One should be familiar with salient clinical and imaging findings of necrotizing fasciitis to facilitate a more rapid and accurate diagnosis and be aware that its diagnosis necessitates immediate discussion with the referring physician.

Presacral myelolipoma: a case report and review of imaging findings

Extra-adrenal myelolipoma is a relatively rare entity, with fewer than 50 cases reported in literature. We present a case of a 79 year-old female who presented for evaluation of hip fracture following trauma, where a lobulated presacral mass with mixed fat/soft tissue attenuation was incidentally seen on initial bone algorithm pelvic CT. Subsequent MRI showed signal characteristics of a lesion with mixed fat and soft tissue composition. The lesion demonstrated stability on follow-up imaging. An elective surgical resection was performed which yielded a grossly fatty mass. The diagnosis of presacral myelolipoma was confirmed on microscopic examination. Following description of our case, we conduct a literature review of the imaging characteristics, diagnosis, and treatment of presacral myelolipoma.

Ureteral rupture from aberrant Foley catheter placement: A case report

We present the case of a 59 year old female with history of severe neurologic dysfunction from advanced multiple sclerosis who presented with lethargy and oliguria several hours after urethral Foley catheterization. A contrast-enhanced CT scan of the abdomen/pelvis showed an aberrantly placed Foley catheter with its balloon inflated in the proximal left ureter, a rare complication of Foley catheterization with only 5 other cases reported. Incomplete ureteral rupture was demonstrated and confirmed by a followup CT scan in the urographic phase. One of our institutions Interventional Radiologists then placed a nephroureteral stent across the injured ureter to facilitate healing. The patient expired 9 days after the procedure from unrelated sepsis from a chronic stage IV decubitus ulcer, so long term monitoring could not be performed. Following description of our case, we conduct a literature review of presentations, imaging characteristics, and treatment of ureteral Foley catheter placement.

Utility of positron emission tomography-magnetic resonance imaging in musculoskeletal imaging

Differentiation between neoplastic and nonneoplastic conditions magnetic resonance imaging (MRI) has established itself as one of the key clinical tools in evaluation of musculoskeletal pathology. However, MRI still has several key limitations which require supplemental information from additional modalities to complete evaluation of various disorders. This has led to the development hybrid positron emission tomography (PET)-MRI which is rapidly evolving to address key clinical questions by using the morphological strengths of MRI and functional information of PET imaging. In this article, we aim to review physical principles and techniques of PET-MRI and discuss clinical utility of functional information obtained from PET imaging and structural information obtained from MRI imaging for the evaluation of musculoskeletal pathology. More specifically, this review highlights the role of PET-MRI in musculoskeletal oncology including initial diagnosis and staging, treatment planning and post-treatment follow-up. Also we will review utility of PET-MRI in evaluating musculoskeletal infections (especially in the immunocompromised and diabetics) and inflammatory condition. Additionally, common pitfalls of PET-MRI will be addressed.

Inadvertent intravesicular placement of a vaginal contraceptive ring: a case report and review of literature.

The NuvaRing® is a deformable, ring-shaped hormonal contraceptive device which is typically vaginally self-inserted by the patient. While there are several potential side effects of usage, essentially all of them result from hormone delivery. Complications from incorrect placement are rare. We present the case of a 31 year old female who presented to our emergency department after being unable to retrieve a NuvaRing® for its scheduled removal. CT scan showed a hypodense intravesicular NuvaRing® which the patient had inadvertently placed transurethrally 3 weeks prior. Cystoscopy was performed and retrieval using a 3-pronged grasper was eventually successful after several failed attempts with an alligator grasper. Our purpose in presenting this case is to introduce the reader to a rare complication of incorrect NuvaRing® placement, explain how this complication may occur as a result of NuvaRing® construction/functionality, describe how alternative cystoscopic instruments may aid in cystoscopic retrieval, and review the 3 other case reports of intravesicular NuvaRing® placement to discuss the utility of various imaging modalities when clinical suspicion of the complication is high.

Isolated Fallopian Tube Torsion: A Case Report and Review of Literature

Isolated fallopian tube torsion is a rare cause of pelvic pain in female patients. We present the case of a 10 year old female without significant past medical history who presented with acute left lower quadrant abdominal pain. A CT scan of the abdomen/pelvis showed a dilated, tortuous, fluid-filled structure in the left adnexal region which was ultimately diagnosed as a torsed fallopian tube. Subsequent trans abdominal ultrasound examination documented the fallopian tube’s lack of vascularity with color Doppler and demonstrated thickened, edematous walls and longitudinal folds. The ipsilateral ovary maintained normal vascularity and was unremarkable. The patient underwent laparoscopic salpingectomy, and pathologic examination of the specimen confirmed hemorrhagic fallopian tube necrosis. The patient recovered without complication, and has not experienced any pain recurrence since the procedure.

Osteochondroma of the hip with adjacent bursal chondromatosis

It is well established that irregular bursae can form adjacent to an osteochondroma (bursa exostotica) as a result of mechanical irritation and that these bursae can be complicated by inflammation, hemorrhage, or infection. Bursal chondromatosis is a rare complication, with only seven published cases in the literature according to our searches. We present the case of a 53-year-old female who presented with slowly progressive left hip/thigh pain and was found to have an osteochondroma arising from the lesser trochanter with numerous ossified bodies in the adjacent soft tissues. MRI demonstrated osteochondral bodies in a fluid-filled bursa adjacent to the osteochondroma, with several of the bodies noted to be fairly displaced from the osteochondroma cartilaginous cap. At surgery, the osteochondroma was removed and numerous bodies of varying sizes were excised, some of which were noted to be adherent to the bursal lining and others that were separated/distant from the cartilage cap. The question arises as to whether this process represents bursal chondromatosis resulting from benign neoplasia of cells lining the abnormal bursa, “cartilage shedding” from the osteochondromatous cap, or both. The purpose in presenting this case is to introduce a rare complication of an osteochondroma, demonstrate that soft tissue calcification and osteochondral densities displaced from an underlying osteochondroma are not always the result of sarcomatous degeneration, and provide support for the theory that cells lining a bursa in a nonphysiologic location can undergo benign neoplasia with subsequent formation of osteochondral bodies.

Crowdsourcing for identification of polyp-free segments in virtual colonoscopy videos

Virtual colonoscopy (VC) allows a physician to virtually navigate within a reconstructed 3D colon model searching for colorectal polyps. Though VC is widely recognized as a highly sensitive and specific test for identifying polyps, one limitation is the reading time, which can take over 30 minutes per patient. Large amounts of the colon are often devoid of polyps, and a way of identifying these polyp-free segments could be of valuable use in reducing the required reading time for the interrogating radiologist. To this end, we have tested the ability of the collective crowd intelligence of non-expert workers to identify polyp candidates and polyp-free regions. We presented twenty short videos flying through a segment of a virtual colon to each worker, and the crowd was asked to determine whether or not a possible polyp was observed within that video segment. We evaluated our framework on Amazon Mechanical Turk and found that the crowd was able to achieve a sensitivity of 80.0% and specificity of 86.5% in identifying video segments which contained a clinically proven polyp. Since each polyp appeared in multiple consecutive segments, all polyps were in fact identified. Using the crowd results as a first pass, 80% of the video segments could in theory be skipped by the radiologist, equating to a significant time savings and enabling more VC examinations to be performed.

Soft tissue aneurysmal bone cyst: a rare case in a middle aged patient

Soft tissue aneurysmal bone cyst is a rare entity, with about 20 cases reported in literature, only 3 of which are in patients over 40 years of age. We present a case of a 41 year old Latin American female who presented for evaluation of atraumatic chest pain with radiation to the left shoulder. Her initial workup was negative, including radiographic imaging of the chest and left shoulder. 4 months later, she presented to her orthopedic surgeon with a palpable mass and mild left shoulder pain. Radiographs acquired at that time demonstrated a 7.0 × 5.5 × 6.7 cm mass with rim calcification in the region of the upper triceps muscle. Subsequent CT imaging showed central areas of hypodensity and thin septations, a few of which were calcified. MR evaluation showed hemorrhagic cystic spaces with multiple fluid-fluid levels and enhancing septations. Surgical biopsy was performed and pathology was preliminarily interpreted as cystic myositis ossificans, however on final review the diagnosis of soft tissue aneurysmal bone cyst was made. The lesion was then surgically excised and no evidence of recurrence was seen on a 3 year post-op radiograph. Following description of our case, we conduct a literature review of the imaging characteristics, diagnosis, and treatment of soft tissue aneurysmal bone cyst.

Crowdsourcing lung nodules detection and annotation

We present crowdsourcing as an additional modality to aid radiologists in the diagnosis of lung cancer from clinical chest computed tomography (CT) scans. More specifically, a complete work flow is introduced which can help maximize the sensitivity of lung nodule detection by utilizing the collective intelligence of the crowd. We combine the concept of overlapping thin-slab maximum intensity projections (TS-MIPs) and cine viewing to render short videos that can be outsourced as an annotation task to the crowd. These videos are generated by linearly interpolating overlapping TS-MIPs of CT slices through the depth of each quadrant of a patients lung. The resultant videos are outsourced to an online community of non-expert users who, after a brief tutorial, annotate suspected nodules in these video segments. Using our crowdsourcing work flow, we achieved a lung nodule detection sensitivity of over 90% for 20 patient CT datasets (containing 178 lung nodules with sizes between 1-30mm), and only 47 false positives from a total of 1021 annotations on nodules of all sizes (96% sensitivity for nodules>4mm). These results show that crowdsourcing can be a robust and scalable modality to aid radiologists in screening for lung cancer, directly or in combination with computer-aided detection (CAD) algorithms. For CAD algorithms, the presented work flow can provide highly accurate training data to overcome the high false-positive rate (per scan) problem. We also provide, for the first time, analysis on nodule size and position which can help improve CAD algorithms.