Sivasubramanian Srinivasan

MRI in necrotizing fasciitis of the extremities

Necrotizing fasciitis is a life-threatening soft-tissue infection of bacterial origin, which involves mainly the deep fascia. Early recognition of this condition may be hampered by the uncommon nature of the disease and non-specificity of initial clinical signs and symptoms in less fulminant cases, making the role of imaging important. MRI is the most useful imaging modality in the diagnosis of necrotizing fasciitis. The presence of thick (>3 mm) hyperintense signal in the deep fascia (particularly intermuscular fascia) on fat-suppressed T2 weighted or short tau inversion-recovery images is an important marker for necrotizing fasciitis. Contrast enhancement of the thickened necrotic fascia can be variable, with a mixed-pattern of enhancement being more commonly encountered. Involvement of multiple musculofascial compartments increases the likelihood of necrotizing fasciitis. It is important to remember that T2-hyperintense signal in the deep fascia is not specific to necrotizing fasciitis and can also be seen in cases such as non-infective inflammatory fasciitis or muscle tear. In this pictorial essay, we aim to review the MRI findings in necrotizing fasciitis, discuss its limitations and pitfalls and identify differentiating features from non-necrotizing soft-tissue infections, such as cellulitis and infective myositis/pyomyositis, conditions which may clinically mimic necrotizing fasciitis.

Diffusion-weighted MRI in acute posterior ischemic optic neuropathy

Blindness following surgery, especially cardiac surgery, has been reported sporadically, the most common cause being ischemic optic neuropathy. The role of MRI in the diagnosis of this condition is not well established. We present a case of postoperative posterior ischemic optic neuropathy that was diagnosed on diffusion-weighted MRI.

Extramedullary Pulmonary Hematopoiesis Causing Pulmonary Hypertension and Severe Tricuspid Regurgitation Detected by Technetium-99m Sulfur Colloid Bone Marrow Scan and Single-Photon Emission Computed Tomography/CT

Extramedullary pulmonary hematopoiesis is a rare entity with a limited number of case reports in the available literature only. We report the case of a 66-year-old man with known primary myelofibrosis, in whom a Technetium-99m sulfur colloid bone marrow scan with single-photon emission computed tomography (SPECT)/CT revealed a pulmonary hematopoiesis as the cause of pulmonary hypertension and severe tricuspid regurgitation. To the best of our knowledge, this is the first description of Technetium-99m sulfur colloid SPECT/CT imaging in this rare condition.

Imaging of acute cholecystitis and cholecystitis-associated complications in the emergency setting.

Acute cholecystitis is a common cause of right upper quadrant pain in patients presenting at the emergency department. Early diagnosis and recognition of associated complications, though challenging, are essential for timely management. Imaging studies, including ultrasonography, computed tomography and magnetic resonance imaging, are increasingly utilised for the evaluation of suspected cases of cholecystitis. These investigations help in diagnosis, identification of complications and surgical planning. Imaging features of acute cholecystitis have been described in the literature and are variable, depending on the stage of inflammation. This article discusses the spectrum of cholecystitis-associated complications and their imaging manifestations. We also suggest a checklist for the prompt and accurate identification of complications in acute cholecystitis.

Isolated retroaortic left innominate vein in an adult without cardiac or aortic anomalies.

Retroaortic innominate vein is an uncommon variant reported in patients with congenital heart disease. However, isolated retroaortic innominate vein without associated cardiac or arch anomalies is extremely rare. We present a case of a 68-year-old man who was found to have this anomalous variant incidentally on computed tomography (CT) of the thorax. We also briefly discuss its associations, embryology, and clinical significance.

RE: Musculoskeletal Applications of Elastography: a Pictorial Essay of Our Initial Experience

Dear Editors: We fully agree that sonoelastography is a very useful in musculoskeletal imaging modality, especially for evaluating tendon tears, early softening, and degenerative changes in the tendons (1, 2). However, it is not easy to perform on all tendons. Scanning an Achilles tendon (3), being superficial, is very easy to scan and similarly, sonoelastography is also very easy given that it is easy to compress the superficial structure. However, the orientation of supraspinatus is complex as it lies deep at bone level and at the deltoid to some extent, and also has an oblique course. Hence, when

Dual-energy CT applications in salivary gland lesions

The increasing availability of dual-energy CT (DECT) has set the stage for an exciting era in CT technology. This technique is extensively used throughout the world with numerous centres working on the applications of DECT in various radiology subspeciality areas. DECT provides many advantages over the conventional single-energy scan. Instead of a single set of images, radiologists have access to multiple sets of images from a single acquisition. The DECT workstation enables the reader to generate images, according to the clinical setting, in order to answer a specific clinical question. Radiologists should be aware of the basic concepts of DECT and the usefulness of each image data set. This article aimed to describe the basic principles, techniques and applications of DECT in the imaging of salivary gland lesions. The specific roles of each image data set, in the context of salivary gland lesions, are also discussed.

An Approach to Various Gastric Pathologies Using an “Image Appearance−Based Classification” on Computed Tomography

Although pathologies affecting stomach are commonly encountered in computed tomography imaging of the abdomen, they are frequently overlooked. Their etiologies are often diverse; however, most of them have certain well-documented imaging characteristics. Conventionally the stomach abnormalities were classified according to their etiopathogenesis. This article aims at providing the readers with an easy approach by categorizing abnormalities of stomach using a novel image appearance-based classification. An attempt to illustrate various gastric pathologies using this new classification by means of pictorial examples is made. Basic computed tomography imaging anatomy of the stomach and imaging techniques that need to be adapted are also emphasized in the outset of the discussion.

Radiography in Osteoporosis

The pathological changes of osteoporosis are due to resorption of the cortical and trabecular bone. The main radiographic findings include changes in the trabecular pattern, cortical thinning, and decreased bone density which are more prominent in the axial skeleton. Although the most common cause is primary osteoporosis, one has to be aware of the secondary causes as well. Conventional radiography helps in evaluating the secondary causes of osteoporosis, to confirm or rule out fractures and to diagnose concomitant or predisposing conditions. However, radiographs have certain limitations. Radiography only helps in qualitative assessment and cannot be considered as a tool for quantitative assessment. This chapter aims to review the radio-pathological changes and various causes of osteoporosis.

Extraosseous uptake of technetium-99m methylene diphosphonate by an acute territorial cerebral infarct in a classical biodistribution pattern

Technetium-99m methylene diphosphonate scintigraphy is usually performed to assess bone lesions, especially skeletal metastases in patients with a history of malignancy. However, it is important to recognize some specific conditions with a unique pattern of tracer uptake, especially in extraosseous locations as they are not related to primary neoplasm or metastases. Diagnosing such unusual presentation is essential as it significantly influences the clinical management. This case report describes an unusual presentation detected in a bone scan of an elderly female patient, who was a treated case of breast cancer and was referred for a bone scan to rule out bone metastases. Incidentally, a large acute territorial cerebral infarct was diagnosed, which was later confirmed by magnetic resonance imaging on diffusion-weighted images. Diagnosis of the typical presentation and timely management saved the patient life.