Maryam Gul

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.

Qualitative assessment of diffusion weighted imaging and susceptibility weighted imaging of myeloid sarcoma involving the brain

Background and Purpose Myeloid sarcoma is a rare form of extramedullary leukemia, which can present with or without systemic leukemia. The purpose of this study was to evaluate characteristic computed tomography (CT) and magnetic resonance imaging (MRI) findings (including diffusion weighted imaging and susceptibility weighted imaging) of myeloid sarcoma involving the brain. Materials and Methods One hundred nine patients with pathologically proven myeloid sarcoma underwent pretreatment CT and MRI, which were retrospectively reviewed. Computed tomography and MRI characteristics reviewed include lesion location, shape, size, architecture, margins, ±multiplicity, ±bone destruction, pattern and degree of enhancement, ±restricted diffusion, and ±susceptibility artifact. Results Twenty-five patients (14 men, 11 women; mean age, 55 years; range, 9–80 years) met the inclusion criteria. Acute myeloid leukemia with subtypes M3 (44.4%) and M5 (22.2%) were the most common. On unenhanced CT, mean lesion size was 1.9 ± 0.4cm; 60% were intra-axial hyperdense masses, 8% were intraventricular hyperdense masses, 12% were isodense intra-axial masses, and 20% of cases were extra-axial hyperdense nodular masses. There was no observable intralesional or perilesional calcium. On MRI, mean lesion size was 2.1 ± 0.6cm. The lesions were isointense (80%) or hypointense (20%) on T1-weighted images with homogeneous (88%) or heterogeneous (12%) enhancement. On fluid-attenuated inversion recovery and T2-weighted images, lesions were hyperintense (96%) or isointense (4%) with mild vasogenic edema. Majority (96%) of cases demonstrated restricted diffusion, whereas only a few (16%) demonstrated susceptibility artifact. Conclusions In patients with history of leukemia or myeloproliferative disorder, identification of homogenous mass hyperdense on unenhanced CT, T1 isointense, and T2/fluid-attenuated inversion recovery hyperintense with restricted diffusion and homogenous postcontrast enhancement without significant susceptibility artifact is suggestive of myeloid sarcoma.

Atypical presentation of CLIPPERS syndrome: A new entity in the differential diagnosis of central nervous system rheumatologic diseases

AbstractNumerous autoimmune diseases can affect the central nervous system (CNS), and variable clinical presentations confound the differential diagnosis. The challenging task of properly characterizing various CNS autoimmune diseases enables patients to be rapidly triaged and appropriately treated. In this review article, we aim to explore different CNS manifestations of rheumatologic diseases with emphasis on the utility of imaging and cerebrospinal fluid findings. We review the classic physical examination findings, characteristic imaging features, cerebrospinal fluid results, and serum biomarkers. In addition, we also present a unique case of newly described autoimmune entity CLIPPERS syndrome. Our case is unique in that this is the first case which demonstrates involvement of the supratentorial perivascular spaces in addition to the classic infratentorial involvement as initially described by Pittock et al (Brain. 2010;133:2626–2634).

Case 238: Spontaneous Pneumothorax Secondary to Intrapulmonary Necrobiotic Rheumatoid Nodule

History A 54-year-old white woman with a history of rheumatoid arthritis who was taking glucocorticoids and methotrexate presented to the emergency department in December with worsening shortness of breath and chest heaviness for 1 week. She reported additional symptoms of weakness, headache, and arthralgia primarily involving her bilateral hands, wrist, ankles, and feet. She denied experiencing fevers, syncope or presyncope, focal neurologic deficits, chest pain, nausea, vomiting, unintentional weight loss, or recent trauma. Additional medical history included hypertension, asthma, degenerative disk disease, and migraine, all of which were reportedly controlled with medications. This patient had a smoking history of 80 pack-years, but she had quit smoking 2 months prior to presentation. She denied abuse of alcohol or recreational drugs and reported she was up-to-date on her immunizations, including those for pneumonia and flu. Family history was pertinent for breast cancer in her mother, sister, and maternal aunt. The patient reported normal findings at screening mammography and colonoscopy. A physical examination was remarkable for slightly asymmetric breath sounds, which appeared to be diminished on the right side. This patient had multiple joint deformities, most notably in the bilateral metacarpophalangeal joints. Initial electrocardiography findings and cardiac biomarkers were negative. Her complete blood count and basic metabolic profile were unremarkable. Posteroanterior and lateral chest radiographs were obtained in the emergency department. Subsequently, computed tomography (CT) of the chest was performed.

Quantitative Evaluation of Noncontrast Computed Tomography of the Head for Assessment of Anemia.

Background and Purpose Anemia is an underdiagnosed clinical entity with significant mortality and morbidity. We aimed to assess whether attenuation of dural venous sinuses correlates with hemoglobin/hematocrit and to determine if the degree of anemia can be predicted by quantitative analysis of unenhanced computed tomography (CT) of the head. Materials and Methods This is an institutional review board–approved retrospective study including 500 patients who underwent emergency department investigation for potential central nervous system etiology of their symptoms with unenhanced CT head at a tertiary care center. Computed tomographic attenuation values were obtained by 2 independent readers, whereas 2 separate investigators collected clinical data. Regression analyses were performed to evaluate the strength of correlation and the predictability of anemia and its severity on unenhanced CT. Receiver operating characteristic curve analyses were performed to evaluate sensitivity, specificity, as well as positive and negative predictive values. Results A total of 243 met the inclusion criteria, and attenuation values for all the dural venous sinuses were averaged and categorized according to hemoglobin values of less than 8, 8 to 10, 10 to 14, and greater than 14. Mean CT attenuation values for both readers were 36.30, 42.35, 47.99, and 53.25 Hounsfield units. Regression analysis revealed the highest positive correlation of hemoglobin/hematocrit with attenuation at the confluence of sinuses with R2 value of 0.63 and 0.60. The sensitivity, specificity, and negative predictive value of detecting hemoglobin of less than 10 at confluence of sinuses were 91.2%, 88.5%, and 98.6%, respectively. Interobserver agreement was found to be good (0.64) using the &kgr; statistic. Conclusions Our study substantiates direct positive correlation between CT attenuation of dural venous sinuses and hemoglobin/hematocrit, with strongest correlation at the confluence of sinuses with good sensitivity, specificity, and negative predictive value.

Imaging Mimics of Necrotizing Soft Tissue Fasciitis: Part II

The topic of imaging of soft tissue infections and their mimics will be presented in two parts: Part I (Volume 38, Number 15) and Part II (Volume 38, Number 16).