Prakash Muthusami

Incidentally detected unilateral pulmonary artery agenesis with pulmonary hypoplasia in a 67 year old woman

Unilateral pulmonary artery agenesis is commonly seen associated with other congenital cardiovascular defects, when it is detected early in life, but isolated absence of the pulmonary artery is a rare entity, usually detected in adulthood. The latter patients are usually asymptomatic or might present with varied non-specific manifestations such as respiratory tract infections and hemoptysis. This report describes the imaging findings of a 67 year old female with absence of the right pulmonary artery. The embryology and clinical manifestations of the condition are reviewed.

Ultrasound guidance for difficult lumbar puncture in children: pearls and pitfalls

Pediatric lumbar puncture can be challenging or unsuccessful for several reasons. At the same time, the excellent sonographic window into the pediatric spine provides a distinct opportunity for ultrasound-guided lumbar puncture. Minimal cerebrospinal fluid and thecal displacement by subdural or epidural hematomas are common after failed clinical attempts. Ultrasound is useful for determining a safe infraconal level for subarachnoid access. Real-time guidance increases not only the success rate but also the safety of diagnostic lumbar puncture and injections for chemotherapy and myelography. In this article, we discuss clinical and technical factors for ultrasound-guided pediatric lumbar puncture.

Diffusion tensor imaging and tractography of the human language pathways: Moving into the clinical realm

The functional correlates of anatomical derangements are of interest to the neurological clinician. Diffusion tensor tractography (DTT) is a relatively new tool in the arsenal of functional neuroimaging, by which to assess white matter tracts in the brain. While much import has been given to tracking corticospinal tracts in neurological disease, studying language pathway interconnections using DTT has largely remained in the research realm. Hardware and software advances have allowed this tool to ease into clinical practice, with several radiologists, neurologists, and neurosurgeons now familiar with its applications. DTT images, although visually appealing, are founded in mathematical equations and assumptions, and require a more than basic understanding of principles and limitations before they can be integrated into routine clinical practice. Cognitive pathways like that of language, that are normally hard to assess and especially more so when pathologically affected, have been at the receiving end of several opposing and often controversial hypotheses, and the past decade has seen the clarification, validation or rejection of several of these by the in vivo charting of functional connectivity using DTT. The focus of this review is to illustrate DTT of the language pathways with emphasis on practical considerations, clinical applications, and limitations.J. Magn. Reson. Imaging 2014;40:1041–1053.

Appearances of the circumcaval ureter on excretory urography and MR urography: A single-center case series

Objectives: To describe Magnetic Resonance Urography (MRU) appearances of the circumcaval ureter, a rare congenital cause of hydronephrosis. Materials and Methods: Seven cases of circumcaval ureter, suspected on intravenous urography (IVU), underwent subsequent static MRU using heavily T2-weighted sequences. Results: The various appearances of circumcaval ureter on IVU and MRU were studied and compared. The circumcaval portion of the ureter was especially well seen on axial MRU sections, though this portion was routinely not visualized on IVU. In one case with a ureteric calculus, MRU also depicted a circumcaval course of the ureter, thus providing a complete diagnosis. In yet another case, where a circumcaval ureter was suspected on IVU, MRU proved the actual cause of ureteric obstruction to be a crossing vessel. Conclusion: Static MRU using heavily T2-weighted coronal and axial sequences can make or exclude the diagnosis of circumcaval ureter unequivocally.

Arterial Wall Imaging in Pediatric Stroke

Background and Purpose— Arteriopathy is common in childhood arterial ischemic stroke (AIS) and predicts stroke recurrence. Currently available vascular imaging techniques mainly image the arterial lumen rather than the vessel wall and have a limited ability to differentiate among common arteriopathies. We aimed to investigate the value of a magnetic resonance imaging-based technique, namely noninvasive arterial wall imaging (AWI), for distinguishing among arteriopathy subtypes in a consecutive cohort of children presenting with AIS. Methods— Children with confirmed AIS and magnetic resonance angiography underwent 3-Tesla AWI including T1-weighted 2-dimensional fluid-attenuated inversion recovery fast spin echo sequences pre- and post-gadolinium contrast. AWI characteristics, including wall enhancement, wall thickening, and luminal stenosis, were documented for all. Results— Twenty-six children with AIS had AWI. Of these, 9 (35%) had AWI enhancement. AWI enhancement was associated with anterior circulation magnetic resonance angiography abnormality and cortical infarction in 8 of 9 (89%) children and normal magnetic resonance angiography with posterior circulation subcortical infarction in 1 (1 of 9; 11%) child. AWI enhancement was not seen in 17 (65%), 10 (59%) of whom had an abnormal magnetic resonance angiography. Distinct patterns of pre- and postcontrast signal abnormality were demonstrated in the vessel wall in the region of interest in children with transient cerebral arteriopathy, arterial dissection, primary central nervous system angiitis, dissecting aneurysm, and cardioembolic stroke. Conclusions— AWI is a noninvasive, high-resolution magnetic resonance AWI technique, which can be successfully used in children presenting with AIS. Patterns of AWI enhancement are recognizable and associated with specific AIS pathogeneses. Further studies are required to assess the additional diagnostic utility of AWI over routine vascular imaging techniques, in childhood AIS.

Splanchnic, Thoracoabdominal, and Cerebral Blood Flow Volumes in Healthy Children and Young Adults in Fasting and Postprandial States: Determining Reference Ranges by Using Phase-Contrast MR Imaging

Purpose To estimate reference ranges for blood flow volume (BFV) in major splanchnic, thoracoabdominal, and neck vessels by using phase-contrast magnetic resonance (MR) imaging in children and young adults in fasting and postprandial states. Materials and Methods In this institutional research ethics board-approved prospective study, healthy volunteers underwent phase-contrast MR imaging in a fasting state and again after a standardized meal. BFV values were reported as medians and ranges, and postmeal to premeal BFV ratios were calculated. BFVs in volunteers divided into two groups according to age (≤18 years old and >18 years old) were compared by using the Mann-Whitney test adjusted for multiple comparisons. Linear regression for internal validation of BFV and Pearson correlation and Bland-Altman analysis for interobserver agreement were used. Results Reference ranges for BFVs were estimated in 39 volunteers (23 male and 16 female; mean age, 21.2 years ± 8.5; range, 9-40 years) and were indexed according to body surface area, with internal validation (R2 = 0.84-0.92) and excellent interobserver agreement (R2 = 0.9928). There was an almost 30% increase in total abdominal BFV (P < .0001) in response to a meal, which was the result of a threefold increase in superior mesenteric artery BFV (P < .0001). BFV after the meal remained unaffected in the celiac artery and cerebral circulation. Significantly higher normalized BFVs in the cerebral circulation were measured in children with both preprandial (P = .039) and postprandial (P = .008) status than those in adults. Conclusion Reference ranges for BFVs and changes in BFVs in response to a meal in major splanchnic, thoracoabdominal, and neck vessels were estimated by using phase-contrast MR imaging in healthy volunteers to allow hemodynamic assessment of children and young adults with various diseases.

Intracranial artery to artery spontaneous revascularization in a child

IntroductionIntracranial artery-to-artery antegrade revascularization is a poorly recognized entity, more so when it involves main stem arteries. The etiology, appearance, and significance of this condition are not described in the literature.Case presentationWe describe a case of spontaneous revascularization of a chronically occluded middle cerebral arterial branch by collaterals from the proximal segment reconstituting distal flow, mimicking a brain arteriovenous malformation in a 9-year old boy. We discuss the nature of these channels, presumed to be related to artery to artery collaterals that are either dilated adventitial vasa vasorum, or, more likely, leptomeningeal collaterals that are hypertrophied in response to cerebral demand. We review the literature regarding intracerebral vasa vasorum and leptomeningeal collaterals including their imaging.ConclusionRecognizing the tortuous channels associated with this type of vascular abnormality as normal vessels reconsituting distal flow may prevent unnecessary and potentially dangerous treatments.

Reduced fetal cerebral oxygen consumption is associated with abnormal white matter in newborns with congenital heart disease

Background Congenital heart disease (CHD) is associated with brain dysmaturation, increased risk of perioperative white matter (WM) injury and neurodevelopmental delay (1). Fetal Doppler studies have shown altered cerebrovascular flow dynamics in CHD, suggesting ‘brain-sparing physiology’. We sought to determine whether postnatal cerebral WM microstructural abnormality relates to abnormal fetal hemodynamics.

Glioma progression as revealed by diffusion tensor metrics

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Clinician and researcher - Can the twain ever meet? A young clinician's perspective

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