Ravi Bhargava

Role of Imaging in Clinical Islet Transplantation

Islet transplantation is an innovative and effective clinical strategy for patients with type 1 diabetes whose clinical condition is inadequately managed even with the most aggressive medical treatment regimens. In islet transplantation, purified islets extracted from the pancreas of deceased donors are infused into the portal vein of the recipient liver. Engrafted islets produce insulin and thus restore euglycemia in many patients. After islet transplantation performed with the original Edmonton protocol, 80% of patients were insulin independent at 1 year and approximately 20% were insulin independent at 5 years. With more recent technical advances, 50% of patients or more maintain insulin independence 5 years after islet transplantation. The success rate with single-donor islet infusions has markedly improved over time. Even in patients who lose insulin independence, islet transplantation is considered successful because it provides improved glycemic control and a higher quality of life. Imaging plays an important role in islet transplantation and is routinely used to evaluate potential recipients, guide the transplantation process, and monitor patients for posttransplantation complications. Because of the success of islet transplantation and its increasing availability worldwide, familiarity with the role of imaging is important.

Cortical tubers, cognition, and epilepsy in tuberous sclerosis.

Tuberous sclerosis complex is an autosomal-dominant genetic disorder characterized by hamartomatous growth in various organs. Patients who have this disorder exhibit a high rate of epilepsy and cognitive problems. We investigated number of tubers, location, seizure types, and cognitive outcome, and we analyzed the relationships among them in our tuberous sclerosis patients in the Comprehensive Epilepsy Program at the University of Alberta. We also examined the seizure outcome after tuber resection. Our study cohort included 24 patients with tuberous sclerosis complex. We obtained seizure history, electroencephalogram, and neuropsychologic parameters. Magnetic resonance imaging was used to examine tuber numbers and locations. Ten patients underwent surgical removal of tubers responsible for intractable epilepsy. A negative correlation was found between the number of tubers and intelligent quotient score. Epilepsy surgery led to freedom from seizures in this patient group. We demonstrated that the total number and location of cortical tubers play a significant role in the extent of mental retardation in patients with tuberous sclerosis complex. In addition, patients with intractable seizures and well-defined epileptic focus had excellent surgical outcome.

Doppler Ultrasound Velocities and Resistive Indexes Immediately After Pediatric Liver Transplantation: Normal Ranges and Predictors of Failure

OBJECTIVEnWe sought to determine the ranges of Doppler ultrasound findings immediately after pediatric liver transplantation that are associated with successful outcomes or postoperative complications.nnnMATERIALS AND METHODSnThis study included consecutive children who underwent Doppler ultrasound less than 48 hours after liver transplantation from 2001 to 2011. Operative reports and clinical outcome data were recorded. We had 110 patients (54% girls) with mean age at transplantation of 2.9 years (median, 1.3 years; range, 0-14 years) and a median follow-up interval of 3.5 years. Two pediatric radiologists reviewed ultrasound images in consensus. We computed descriptive statistics, interindex correlations, and analysis of variance.nnnRESULTSnTwenty-four of 110 patients had a vascular complication, most commonly hepatic arterial thrombosis (seven patients). Compared with published adult normal values, normal pediatric Doppler parameters at postoperative day 1 trended toward higher normal velocities and resistive indexes (up to 0.95). Absent or low-velocity common hepatic artery flow less than 50 cm/s or a common hepatic artery resistive index less than 0.50 were significantly associated with hepatic artery thrombosis, whereas absent or low-velocity portal venous flow less than 30 cm/s or low-velocity hepatic venous flow less than 25 cm/s were significantly associated with vascular complications and a monotonic hepatic venous waveform was significantly associated with venous complications.nnnCONCLUSIONnFlow in a pediatric liver on the first day after transplantation is normally hyperdynamic, especially in the youngest transplant recipients, and, as a result, low velocities or resistive indexes are particularly concerning for complications. The pediatric-specific ranges of expected posttransplantation Doppler ultrasound findings presented in this article should assist in identifying normal variation and potentially life-threatening complications.

Diploic venous anatomy studied in-vivo by MRI.

Calvarial diploic venous anatomy has been studied post‐mortem, but few studies have addressed these venous structures in‐vivo. Previous work in our laboratory has shown that intraosseous infusion through the skull diploic space near the diploic veins in animals and humans does access the superior sagittal sinus and the systemic venous system. We developed a volumetric method of imaging the diploic veins in‐vivo using MRI, intravenous gadolinium, and digital subtraction to provide for three‐dimensional depiction and exact localization of these veins. We hypothesized that this technique would allow for an assessment of the probability of existence, distribution, and concentration of diploic veins in the skull. We scanned 31 neurosurgical patients, and were able to create 3D diploic venous maps in 74% of them. These maps were processed using Adobe Photoshop CS2. Mathworks MatLab 6.5, once customized, counted the number of pixels occupied by the diploic veins in the processed image. The probability of veins was highest in the occipital regions (100%). The inferior occipital (4.1%) and posterior parietal (4.1%) regions had the highest concentrations of diploic veins. Digital subtraction venography using a volumetric MRI sequence can demonstrate the diploic veins in‐vivo. The inferior occipital region may be the best area for an intraosseous infusion device because it has the greatest likelihood of containing a vein and also has the highest concentration of veins. Clin. Anat. 22:296–301, 2009.

Intracranial calcification, retinopathy, and osteopenia: a new syndrome?

We describe two brothers with bilateral exudative retinopathy, intracranial calcifications, a sclerotic bony disorder, and normal intelligence. The younger brother also has osteopenia, mild splenomegaly, and pancytopenia. We review the literature with emphasis on the unique features of these patients.

How specific is the MRI appearance of supratentorial atypical teratoid rhabdoid tumors

BackgroundSupratentorial atypical teratoid rhabdoid tumor (ATRT) in many cases has a distinctive appearance on post-gadolinium MRI.ObjectiveWe sought to determine whether this is a unique appearance allowing ATRT to be distinguished accurately from other types of pediatric supratentorial tumors.Materials and methodsRetrospective review of all available preoperative MRI of pediatric supratentorial tumors at two tertiary children’s hospitals, and systematic literature review of case series and reports describing the MRI imaging appearances of supratentorial ATRT.ResultsWe had 61 supratentorial tumors, including 32 gliomas, 6 ATRT, 8 ependymomas, 6 gangliogliomas, 2 pilomyxoid astrocytomas, 3 primitive neuro-ectodermal tumors, 2 choroid plexus papillomas, and 2 meningiomas. ATRT presented in significantly younger patients than astrocytomas (mean age 2.6xa0years vs. 9.9xa0years, Pu2009<u20090.05). The visual pattern of a thick, wavy (irregular) heterogeneously enhancing wall around a cystic center was seen in 5/6 (83%) ATRTs and only 3/55 (5.4%) other tumors (Pu2009<u20090.0001), for specificity of 95%, sensitivity of 83%, positive predictive value of 63% and a negative predictive value of 95%.ConclusionA supratentorial tumor with a thick, wavy (irregular) heterogeneously enhancing wall surrounding a central cystic region is suggestive of ATRT in the appropriate clinical setting, especially in a child of preschool age.

Long-term follow-up of hepatic ultrasound findings in subjects with magnetic resonance imaging defined hepatic steatosis following clinical islet transplantation: A case-control study

Hepatic steatosis is one complication patients may experience following clinical islet transplantation (CIT), yet the cause and consequences of this are poorly understood. The purpose of this case-control study was to examine the relationship between hepatic steatosis, metabolic parameters and graft function in an Albertan cohort of CIT recipients. Hepatic steatosis was detected by magnetic resonance imaging (MRI) in n = 10 cases age-matched with n=10 MRI-negative controls. Progression/regression of steatosis was determined by ultrasound (US) in cases. Hepatic steatosis first appeared 2.8 ± 2.2 (mean ± SD) years post-CIT, and lasted approximately 4.6 ± 2.0 years. In five cases steatosis resolved, with recurrence in two cases during the follow-up period (8.5 ± 3.2 years). No evidence of CIT causing deleterious effects on long-term liver function or graft outcome was observed.

Primitive neuroectodermal tumor of the diaphragm : case report

Abstract We present a case of primitive neuroectodermal tumor (PNET) arising from the diaphragm in a neonate. PNETs are rare malignant tumors that belong to the group of small, round, blue-cell neoplasms of childhood. To the best of our knowledge, a PNET originating from the diaphragm has not been previously reported.

Answer to Case of the Month #156: Dermoid Cyst Presenting As Congenital Midline Nasal Mass in 6-Month-Old Infant

In the midline, just above the bridge of the nose in the glabellar region, a 0.6 0.7 1.1 cm (anteroeposterior [AP] by transverse by craniocaudal) lesion was identified and corresponded to the lump seen clinically. It was confined adjacent to the frontal bone, and, although there was slight scalloping of the cortex of the frontal bone, it did not extend intracranially. It was well defined and homogeneously T2 bright (Figure 1). It had a few-millimetres-thick rim of relative T1 hyperintensity and was low T1 signal centrally (Figure 2). The relative T1 hyperintense area decreased signal with fat saturation (Figure 3).