Pradeep Goyal

Grading of oligodendroglial tumors of the brain with apparent diffusion coefficient, magnetic resonance spectroscopy, and dynamic susceptibility contrast imaging

Purpose We explored whether advanced magnetic resonance (MR) imaging techniques could grade oligodendrogliomas. Methods Forty patients (age 9–61 years) with oligodendroglial tumors were selected. There were 23 patients with World Health Organization grade II (group 1) and 17 patients with grade III (group 2) tumors. Apparent diffusion coefficient (ADC) maps were calculated by b values of 0 and 1000 s/mm2. Dynamic susceptibility contrast (DSC) images were obtained during the first pass of a bolus of gadolinium-based contrast. These data were post-processed and cerebral blood volume (CBV) maps and permeability (PS) were calculated. MR spectroscopy was acquired after drawing a region of interest on the tumor using two-dimensional chemical shift imaging. Statistical analysis was performed using SPSS software. Results When the rPSmax was combined with the rCBVmax, there was a significant difference between the two groups (p ≤ 0.03) with area under the curve of 0.742 (95% CI: 0.412–0.904). rCBV, rADC, choline/creatine, and choline/NAA alone were able to differentiate between the two groups; however, they did not show any statistical difference with p values of ≤ 0.121, ≤ 0.722, and ≤ 0.582, respectively. A CBV PS product threshold of 0.53 provided a sensitivity of 80% and a specificity of 83.3% in detection of grade III tumors. Conclusion Combined rCBVmax and rPSmax can be utilized to grade oligodendrogliomas. ADC values, relative cerebral blood volume (rCBV), and MR spectroscopy alone can be utilized to differentiate between the two groups of oligodendrogliomas but without statistical significance.

Isolated medial longitudinal fasciculus syndrome: Review of imaging, anatomy, pathophysiology and differential diagnosis:

Isolated medial longitudinal fasciculus (MLF) syndrome due to infarction limited only to the midbrain is a rare occurrence. The MLF are a group of fiber tracts located in the paramedian area of the midbrain and pons. They control horizontal eye movements by interconnecting oculomotor and abducens nuclei in the brain stem. Such small infarcts can easily be overlooked by young neuroradiologists and trainees. In this review, we discuss the clinical and imaging characteristics, comprehensive review of the anatomy, pathophysiology, and differential diagnosis.

Usefulness of enhancement-perfusion mismatch in differentiation of CNS lymphomas from other enhancing malignant tumors of the brain

Background Surgical planning and treatment options for primary or secondary central nervous system lymphomas (PCNSL or SCNSL) are different from other enhancing malignant lesions such as glioblastoma multiforme (GBM), anaplastic gliomas and metastases; so, it is critical to distinguish them preoperatively. We hypothesized that enhancement-perfusion (E-P) mismatch on dynamic susceptibility weighted magnetic resonance (DSC-MR) perfusion imaging which corresponds to low mean relative cerebral blood volume (mean rCBV) in an enhancing portion of the tumor should allow differentiation of CNS lymphomas from other enhancing malignant lesions. Methods We retrospectively reviewed pre-treatment MRI exams, including DSC-MR perfusion images of 15 lymphoma patients. As a control group, pre-treatment DSC-MR perfusion images of biopsy proven 18 GBMs (group II), 13 metastases (group III), and 10 anaplastic enhancing gliomas (group IV) patients were also reviewed. Region of interests (ROIs) were placed around the most enhancing part of tumor on contrast-enhanced T1WI axial images and images were transferred onto co-registered DSC perfusion maps to obtain CBV in all 4 groups. The mean and maximum relative CBV values were obtained. Statistical analysis was performed on SPSS software and significance of the results between the groups was done with Mann-Whitney test, whereas optimal thresholds for tumor differentiation were done by receiver operating characteristic (ROC) analysis. Results The enhancing component of CNS lymphomas were found to have significantly lower mean rCBV compared to enhancing component of GBM (1.2 versus 4.3; P<0.001), metastasis (1.2 versus 2.7; P<0.001), and anaplastic enhancing gliomas (1.2 versus 2.4; P<0.001). Maximum rCBV of enhancing component of lymphoma were significantly lower than GBM (3.1 versus 6.5; P<0.001) and metastasis (3.1 versus 4.9; P<0.013), and not significantly lower than anaplastic enhancing gliomas (3.9 versus 4.2; P<0.08). On the basis of ROC analysis, mean rCBV provided the best threshold [area under the curve (AUC) =0.92] and had better accuracy in differentiating malignant lesions. Conclusions E-P mismatch in DSC perfusion MR, i.e., low mean rCBV in an enhancing portion of the tumor is strongly suggestive of lymphoma and should allow differentiation of CNS lymphoma from other enhancing malignant lesions.

Orbital apex disorders: Imaging findings and management

Orbital apex disorders include orbital apex syndrome, superior orbital fissure syndrome and cavernous sinus syndrome. These disorders result from various etiologies, including trauma, neoplastic, developmental, infectious, inflammatory as well as vascular causes. In the past, these have been described separately based on anatomical locations of disease process; however, these three disorders share similar causes, diagnostic evaluation and management strategies. The etiology is diverse and management is directed to the causative process. This imaging review summarizes the pertinent anatomy of the orbital apex and illustrates representative pathological processes that may affect this region. The purpose of this review is to provide an update on the current status of diagnostic imaging and management of patients with orbital apex disorders.

Clinical and imaging features of pituitary apoplexy and role of imaging in differentiation of clinical mimics

To discuss the clinical syndrome, review common imaging findings of pituitary apoplexy (PA) and role of imaging in therapy and follow-up. Also, to review other acute clinical scenarios with similar clinical and/or imaging findings as PA. PA is a severe and potentially life-threatening medical emergency, characterized by constellation of symptoms/signs that occur as a result of acute hemorrhage and/or infarction in pituitary gland. Patients present with acute and sudden onset of symptoms/signs, most commonly with severe headache, vision deficits/ophthalmoplegia, altered mental status, and possible pan hypopituitarism. Pre-existing macro adenoma (65-90%), especially non-functioning and prolactinomas, are most susceptible to apoplexy, which undergoes hemorrhage or infarct, but PA can occur with normal pituitary or microadenoma. Because of the probable grave prognosis of PA, imaging characteristics of PA and other acute clinical scenarios with similar clinical and/or imaging findings should be familiar to radiologists. PA is potentially a life-threatening clinical syndrome, however, imaging and clinical findings can lead the radiologist towards appropriate diagnosis, and rule out other clinical mimics. When hemorrhage is secondary to an underlying lesion, regrowth of the pituitary tumor years after a PA episode is possible and patients require long-term clinical and imaging surveillance.

Survival prediction based on qualitative MRI diffusion signature in patients with recurrent high grade glioma treated with bevacizumab

Background Bevacizumab was approved by the FDA for the treatment of recurrent or progressive glioblastoma (GBM). Imaging responses are typically assessed by gadolinium-enhanced MRI. We sought to determine the significance of qualitative diffusion signature (manifest as variable degree of dark signal) on ADC maps in recurrent gliomas after treatment with bevacizumab. Methods We performed an institutional review board (IRB) approved retrospective study on patients who underwent MRI of the brain after 8 weeks of receiving bevacizumab for recurrent glioma. Patients were divided into three groups based on qualitative diffusion signature: (I) lesion not bright on diffusion weighted imaging (DWI) suggestive of no restricted diffusion (FDR0); (II) lesion bright on DWI with corresponding homogenous dark signal on apparent diffusion coefficient (ADC) maps suggestive of focal restricted diffusion likely due to bevacizumab induced necrosis (FDRn); and (III) lesion bright on DWI with corresponding homogenous faint dark signal on ADC maps suggestive of focal restricted diffusion likely due to viable tumor or heterogeneous spectrum of dark and faint dark signals on ADC maps suggestive of focal restricted diffusion likely due to viable tumor surrounding the bevacizumab induced necrosis (FDRt). Results Based on the qualitative signal on diffusion weighted sequences after bevacizumab therapy, total number of patients in group (I) were 14 (36%), in group (II) were 17 (44%); and in group (III) were 8 (20%). The median overall survival (OS) from the time of recurrence in patients belonging to group (II) was 364 days vs. 183 days for those with group (I) vs. 298 days for group (III). On simultaneous comparison of survival differences in all three groups by Kaplan-Meier analysis, group (II) was significant in predicting survival with P values for the log-rank tests <0.033. Conclusions In patients with recurrent glioma treated with bevacizumab, the presence of homogenous dark signal (FDRn) on ADC maps at 8 weeks follow-up MRI correlated with a longer survival. Thus, use of this qualitative diffusion signature in adjunct to contrast enhanced MRI may have the widest potential impact on routine clinical care for patients with recurrent high-grade gliomas. However, prospective studies analysing its predictive value are warranted.

Unusual cause of severe diabetic ketoacidosis precipitated by Streptococcus bovis/equinus (SBSEC) bacteremia: Case report and review of literature

Diabetic ketoacidosis is a feared complication in patients with diabetes mellitus and poses high risk of mortality and morbidity unless treated in timely manner. Infection is one of the most common precipitating factors for the development of diabetic ketoacidosis. Bacteremia with Group A and Group B beta hemolytic streptococcal strains are well known, however nonenterococcal Group D strains such as the Streptococcus bovis/Streptococcus equinus complex (SBSEC) still remains an understudied entity. Here we present a case of a 35-year-old Type I diabetic female presenting with severe diabetic ketoacidosis with overlapping features of hyperosmolar hyperglycemia, precipitated by Streptococcus alactolyticus bacteremia, successfully treated with four-week course of parenteral ceftriaxone. This case report emphasizes the potential importance of SBSEC as an emerging pathologic strain and culprit for triggering diabetic ketoacidosis which requires prompt diagnosis and targeted therapy.

Recurrent diabetic myonecrosis –an under-diagnosed cause of acute painful swollen limb in long standing diabetics

Diabetic myonecrosis (DMN) is an under-diagnosed complication of long-standing poorly controlled diabetes mellitus. It presents as abrupt pain and swelling of the extremity, mostly lower limbs. Diagnosis is often delayed as it mimics a number of clinical entities such as deep vein thrombosis (DVT), cellulitis, necrotizing fasciitis and malignancy. Failure to properly identify this condition can result in increased morbidity through exposure to unnecessary tests and biopsy. A 56-year-old male with a history of complicated type 2 diabetes mellitus, hypertension presented to emergency with gradually worsening left calf pain for last 2 weeks. A lower-extremity venous Doppler was negative for DVT. Magnetic resonance imaging (MRI) was suggestive of muscle edema likely of inflammatory etiology. Muscle biopsy revealed myonecrosis with ischemic myopathy and was negative for vasculitis or inflammatory myopathy. He was managed conservatively and his symptoms resolved in 4 weeks. After 6 months he had recurrence in right thigh which was managed conservatively too. Given these findings, a diagnosis of recurrent diabetic myonecrosis was made. Myonecrosis is a less known microvascular complications of diabetes and should always be keep in mind when evaluating a diabetic patient with muscle pain. Diagnosis can be made on MRI in appropriate clinical settings. The clinical course is usually self-limiting and patients respond well to supportive medical therapy that involves bed rest, strict glycemic control along with analgesic.

Do we really care about incidental lung nodules?—Review of atypical lung carcinoid and a proposal for systematic patient follow up

Atypical lung carcinoids are intermediate-grade neuroendocrine tumors (NETs) with malignant potential. They are often detected incidentally on imaging done for non-related causes, as the patients are frequently asymptomatic. Histopathology is required to confirm the diagnosis with immunohistochemistry (IHC). Due to their indolent nature, these are often diagnosed only in the advanced stages. Treatment options include chemoradiation for widespread disease versus surgery for local or minimally invasive disease. This article describes a nonsmoker female with enlarging solitary pulmonary nodule who was initially lost to follow up, subsequently operated and with final pathology revealing atypical lung carcinoid. This case stress on the schematic follow up of these incidentally detected pulmonary nodules. Inspired from the mandatory lay mammography report letters recommended by ACR, this article proposes sending lay letters to patients for pulmonary nodule follow up, directly from the Radiology Department to reinforce the importance of timely follow up, which will complement the information provided to the patient from their primary care physician or pulmonologists office.

Modified palliative biliary stenting in situs inversus totalis patient with carcinoma gallbladder: feasibility and technical details

Knowledge of the anatomical variants is essential for all invasive hepatobiliary procedures such as endoscopy, surgery and radiologic interventions. Modification in standard therapeutic interventions may be required based on variant anatomy. We report a technical modification in a 75-year-old female with known situs inversus (SI) totalis with carcinoma gallbladder. Present case highlights the finer technical details of the modified percutaneous transhepatic biliary drainage (PTBD) procedure and biliary stenting in a SI patient with carcinoma gallbladder causing malignant biliary obstruction.