Dhanashree Rajderkar

Perfusion and permeability MR imaging of gliomas.

Conventional contrast-enhanced MR imaging is the current standard technique for the diagnosis and treatment evaluation of gliomas and other brain neoplasms. However, this method is quite limited in its ability to characterize the complex biology of gliomas and so there is a need to develop more quantitative imaging methods. Perfusion and permeability MR imaging are two such techniques that have shown promise in this regard. This review will highlight the underlying principles, applications, and pitfalls of these evolving advanced MRI methods.

Role of Magnetic Resonance Imaging, Cerebrospinal Fluid, and Electroencephalogram in Diagnosis of Sporadic Creutzfeldt-Jakob Disease

Sporadic Creutzfeldt-Jakob disease (sCJD) is a rapidly progressive dementia (RPD) that can be difficult to identify antemortem, with definitive diagnosis requiring tissue confirmation. We describe the clinical, magnetic resonance imaging (MRI), cerebrospinal fluid (CSF), and electroencephalogram (EEG) measures of a small cohort of 30 patients evaluated for RPD. Clinical and diagnostic measures were cross-sectionally obtained from 17 sCJD patients (15 definite, two probable), 13 non-prion rapidly progressive dementia patients (npRPD), and 18 unimpaired controls. In a subset of patients (nine sCJD and nine npRPD) diffusion tensor imaging (DTI) measures [fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD)] were also obtained for the caudate, corpus callosum, posterior limb of the internal capsule, pulvinar, precuneus, and frontal lobe. Differences among groups were assessed by an analysis of variance. Compared to npRPD individuals, sCJD patients had cerebellar dysfunction, significantly higher CSF tau, “positive” CSF 14-3-3, and hyperintensities on diffusion-weighted imaging (DWI) that met previously established imaging criteria for sCJD. EEG changes were similar for the two groups. In addition, sCJD patients had significant decreases in DTI measures (MD, AD, RD but not FA) within the caudate and pulvinar compared to either npRPD patients or unimpaired controls. Our results confirm that CSF abnormalities and MRI (especially DWI) can assist in distinguishing sCJD patients from npRPD patients. Future longitudinal studies using multiple measures (including CSF and MRI) are needed for evaluating pathological changes seen in sCJD patients.

Susceptibility-Weighted Imaging Helps to Discriminate Pediatric Multiple Sclerosis From Acute Disseminated Encephalomyelitis

BACKGROUND Susceptibility-weighted imaging is a relatively new magnetic resonance imaging sequence that can identify lesions of multiple sclerosis in adults. This study was designed to determine if susceptibility-weighted imaging is a useful discriminator between children who develop multiple sclerosis and children with monophasic acute disseminated encephalomyelitis. METHODS Eighteen children who presented with acute central nervous system demyelination and had a brain magnetic resonance imaging study including susceptibility-weighted imaging within 6 months of the first clinical attack were studied. Final diagnosis was based on international consensus definitions. Brain lesions detected on the fluid-attenuated inversion recovery sequence were assessed for abnormal signal on susceptibility-weighted imaging. The burden of susceptibility abnormalities was then analyzed for differences between the multiple sclerosis and acute disseminated encephalomyelitis groups. RESULTS Eight patients had a final diagnosis of acute disseminated encephalomyelitis and ten had multiple sclerosis. Twenty-two percent of fluid-attenuated inversion recovery lesions were identified on susceptibility-weighted imaging. The percentage of fluid-attenuated inversion recovery lesions identified on susceptibility-weighted imaging differed between the multiple sclerosis and acute disseminated encephalomyelitis groups (P = 0.04). The median percentage (minimum-maximum) of lesions identified on susceptibility-weighted imaging in the multiple sclerosis group was 0.22 (0-0.68) and in the acute disseminated encephalomyelitis group was 0.0 (0-0.17). CONCLUSION Susceptibility-weighted imaging may be a useful technique in differentiating acute disseminated encephalomyelitis from multiple sclerosis at initial presentation.

Comparison of Perfusion- and Diffusion-weighted Imaging Parameters in Brain Tumor Studies Processed Using Different Software Platforms

RATIONALE AND OBJECTIVES To compare quantitative imaging parameter measures from diffusion- and perfusion-weighted imaging magnetic resonance imaging (MRI) sequences in subjects with brain tumors that have been processed with different software platforms. MATERIALS AND METHODS Scans from 20 subjects with primary brain tumors were selected from the Comprehensive Neuro-oncology Data Repository at Washington University School of Medicine (WUSM) and the Swedish Neuroscience Institute. MR images were coregistered, and each subjects data set was processed by three software packages: 1) vendor-specific scanner software, 2) research software developed at WUSM, and 3) a commercially available, Food and Drug Administration-approved, processing platform (Nordic Ice). Regions of interest (ROIs) were chosen within the brain tumor and normal nontumor tissue. The results obtained using these methods were compared. RESULTS For diffusion parameters, including mean diffusivity and fractional anisotropy, concordance was high when comparing different processing methods. For perfusion-imaging parameters, a significant variance in cerebral blood volume, cerebral blood flow, and mean transit time (MTT) values was seen when comparing the same raw data processed using different software platforms. Correlation was better with larger ROIs (radii ≥ 5 mm). Greatest variance was observed in MTT. CONCLUSIONS Diffusion parameter values were consistent across different software processing platforms. Perfusion parameter values were more variable and were influenced by the software used. Variation in the MTT was especially large suggesting that MTT estimation may be unreliable in tumor tissues using current MRI perfusion methods.

An “accidental” discovery: Incidentally found metanephric adenofibroma in a 5-year-old male trauma patient

Metanephric adenofibroma is a rare pediatric renal tumor, which should be considered in cases of solid renal lesions that mimic Wilms tumor on both imaging and histology. We present a case of an incidentally found left renal lesion on a trauma computed tomography scan in a 5-year-old male patient. The patient underwent total nephrectomy, and the diagnosis of metanephric adenofibroma was made on histology. Radiologists should consider this entity in the differential for an incidentally found solitary renal mass in a pediatric patient. Prompting the pathologic diagnosis of this entity can spare patients from unnecessary chemotherapy and allow for nephron-sparing surgery.

Organ doses in pediatric patients undergoing cardiac‐centered fluoroscopically guided interventions: Comparison of three methods for computational phantom alignment

PURPOSE To assess various computational phantom alignment techniques within Monte Carlo radiation transport models of pediatric fluoroscopically guided cardiac interventional studies. METHODS Logfiles, including all procedure radiation and machine data, were extracted from a Toshiba infinix-I unit in the University of Florida Pediatric Catheterization Laboratory for a cohort of 10 patients. Two different alignment methods were then tested against a ground truth standard based upon identification of a unique anatomic reference point within images co-registered to specific irradiation events within each procedure. The first alignment method required measurement of the distance from the edge of the exam table to the top of the patients head (table alignment method). The second alignment method fixed the anatomic reference point to be the geometric center of the heart muscle, as all 10 studies were cardiac in nature. Monte Carlo radiation transport simulations were performed for each patient and intervention using morphometry-matched hybrid computational phantoms for the reference and two tested alignment methods. For each combination, absorbed doses were computed for 28 organs and root mean square organ doses were assessed and compared across the alignment methods. RESULTS The percent error in root mean square organ dose ranged from -57% to +41% for the table alignment method, and from -27% to +22% for the heart geometric centroid alignment method. Absorbed doses to specific organs, such as the heart and lungs, demonstrated higher accuracy in the heart geometric centroid alignment method, with average percent errors of 10% and 1.4%, respectively, compared to average percent errors of -32% and 24%, respectively, using the table alignment method. CONCLUSIONS Of the two phantom alignment methods investigated in this study, the use of an anatomical reference point - in this case the geometric centroid of the heart - provided a reliable method for radiation transport simulations of organ dose in pediatric interventional cardiac studies. This alignment method provides the added benefit of requiring no physician input, making retrospective calculations possible. Moving forward, additional anatomical reference methods can be tested to assess the reliability of anatomical reference points beyond cardiac centered procedures.

Can Neonatal Brain MRI be Performed during Active Cooling

Objective Due to logistical constraints, physicians traditionally delay diagnostic imaging for neonatal hypoxic‐ischemic encephalopathy (HIE) until the neonate has completed all 72 hours of therapeutic hypothermia and rewarming. In some cases, neonates may require neuroimaging before 72 hours has passed. Study Design We present a case in which an MRI was acquired during active hypothermia. Results Upon return to the NICU, Baby Xs temperature probe read 33.6 degrees, indicating that hypothermia was likely maintained at the target temperature. Conclusion Active hypothermia is possible during MRI.

Emergent presentation of Langerhans cell histiocytosis in a pediatric patient: Acute cerebellar involvement causing obstructive hydrocephalus requiring posterior fossa decompression

Langerhans cell histiocytosis (LCH) is a disorder of the monocyte-macrophage system that can be unifocal or systemic. Here, we present a pediatric case who initially presented with osseous LCH but again presented 6 years later emergently with cerebellar symptoms, cerebellar mass and obstructive hydrocephalus. Patient underwent biopsy of the cerebellum which was path proven intracranial LCH.

Common and Uncommon Causes of Ventriculoperitoneal Shunt Malfunction Diagnosed on Plain Radiographs

Thousands of patients with hydrocephalus are treated successfully with ventriculoperitoneal shunts. Ventriculoperitoneal shunts are known to have high malfunction rates, most of which are owing to mechanical causes. When shunt malfunction is suspected, shunt series are often performed to evaluate the mechanical causes of malfunction. These initial radiographs have proven critical in guiding subsequent management. This article is designed to review the various causes of shunt malfunction that can be diagnosed with radiographs.

10-Year-Old Female with Acute Abdominal Pain with Pancreatic Mass

A previously healthy 10-year-old female presented to a local emergency department following three days of nausea and vomiting diagnosed with a solid pseudopapillary tumor. Solid pseudopapillary neoplasms are a rare form of pancreatic cystic neoplasm that typically presents in young females in their 20–30s and are very rare in children. These neoplasms often present as an asymptomatic tumor found on incidental imaging. When symptomatic they most commonly present with abdominal pain and can also cause a palpable abdominal mass, weight loss, gastrointestinal obstruction, and nausea and vomiting. Timely diagnosis of this rare neoplasm is very important because complete resection of the tumor is the definitive treatment and leads to an excellent long-term survival.