Stephen F. Kralik

Radiation Necrosis in Pediatric Patients with Brain Tumors Treated with Proton Radiotherapy

The authors performed a retrospective study on 60 consecutive pediatric patients with primary brain tumors treated with proton radiation therapy. Thirty-one percent of patients developed radiation necrosis with a median time to development of 5 months. They conclude that patients with pediatric brain tumors treated with proton radiation therapy demonstrate a high incidence of radiation necrosis and a short time to development of necrosis. Multiple small areas of necrosis are frequently identified on imaging. BACKGROUND AND PURPOSE: Proton radiotherapy has been increasingly utilized to treat pediatric brain tumors, however, limited information exists regarding radiation necrosis among these patients. Our aim was to evaluate the incidence, timing, clinical significance, risk factors, and imaging patterns of radiation necrosis in pediatric patients with brain tumors treated with proton radiation therapy. MATERIALS AND METHODS: A retrospective study was performed on 60 consecutive pediatric patients with primary brain tumors treated with proton radiation therapy. Radiation necrosis was assessed by examining serial MRIs and clinical records to determine the incidence, timing, risk factors, imaging patterns, and clinical significance associated with the development of radiation necrosis in these patients. Radiation necrosis was defined as areas of new enhancement within an anatomic region with previous exposure to proton beam therapy with subsequent decrease on follow-up imaging without changes in chemotherapy. RESULTS: Thirty-one percent of patients developed radiation necrosis with a median time to development of 5.0 months (range, 3–11 months). Risk factors included multiple chemotherapy agents (>3 cytotoxic agents) and atypical teratoid rhabdoid tumor pathology (P = .03 and P = .03, respectively). The most common imaging patterns were small (median, 0.9 cm) and multifocal (63% of patients) areas of parenchymal enhancement remote from the surgical site. The median time to complete resolution on imaging was 5.3 months (range, 3–12 months). Among patients with imaging findings of radiation necrosis, 25% demonstrated severe symptoms with medical intervention indicated. CONCLUSIONS: Pediatric patients with brain tumors treated with proton radiation therapy demonstrate a high incidence of radiation necrosis and a short time to development of necrosis. Multiple small areas of necrosis are frequently identified on imaging. Exposure to multiple chemotherapy agents was a significant risk factor associated with radiation necrosis in these patients.

Diffusion Imaging for Tumor Grading of Supratentorial Brain Tumors in the First Year of Life

BACKGROUND AND PURPOSE: Supratentorial tumors in the first year of life are typically large and heterogeneous at presentation, making differentiation of these CNS neoplasms on pre-operative imaging difficult. We hypothesize that the ADC value can reliably differentiate high- versus low-grade supratentorial tumors in this patient population. MATERIALS AND METHODS: A blinded review of ADC maps was performed on 19 patients with histologically proved supratentorial brain tumors diagnosed within the first year of life. Minimum ADC values obtained by region of interest from 2 neuroradiologists were averaged and compared with World Health Organization tumor grade. ADC values for the entire tumor were also obtained by use of a semi-automated histogram method and compared with World Health Organization tumor grade. Data were analyzed by use of Spearman ρ and Student t test, with a value of P < .05 considered statistically significant. RESULTS: For the manual ADC values, a significant negative correlation was found between the mean minimum ADC and tumor grade (P = .0016). A significant difference was found between the mean minimum ADC of the low-grade (1.14 × 10−3 mm2/s ± 0.30) and high-grade tumors (0.64 × 10−3 mm2/s ± 0.28) (P = .0018). Likewise, the semi-automated method demonstrated a significant negative correlation between the lowest 5th (P = .0002) and 10th (P = .0009) percentile individual tumor ADC values and tumor grade, a significant difference between the mean 5th and 10th percentile ADC values of the low-grade and high-grade groups (P = .0028), and a significant positive correlation with values obtained by manual region-of-interest placement (P < .000001). CONCLUSIONS: ADC maps can differentiate high- versus low-grade neoplasms for supratentorial tumors presenting in the first year of life, given the significant negative correlation between ADC values and tumor grade.

Evaluation of Orbital Disorders and Cranial Nerve Innervation of the Extraocular Muscles

A wide range of orbital disorders, including an orbital mass, infection, inflammation, systemic disease, or intracranial lesions, may be encountered with imaging. Evaluation of orbital disorders requires the combination of accurate and relevant clinical information with an understanding of anatomy and pathologic processes. An imaging approach to an orbital differential diagnosis includes assessment for alteration of a normal orbital structure, a lesion that does not belong in the orbit, or alteration of the orbit from bone or periorbital disorders. This approach, combined with key elements of clinical history, leads to a narrower differential diagnosis and improved patient care.

Intracranial chordoma presenting as acute hemorrhage in a child: Case report and literature review.

Background: Chordomas are rare, slow-growing malignant neoplasms derived from remnants of the embryological notochord. Pediatric cases comprise only 5% of all chordomas, but more than half of the reported pediatric chordomas are intracranial. For patients of all ages, intracranial chordomas typically present with symptoms such as headaches and progressive neurological deficits occurring over several weeks to many years as they compress or invade local structures. There are only reports of these tumors presenting acutely with intracranial hemorrhage in adult patients. Case Description: A 10-year-old boy presented with acute onset of headache, emesis, and diplopia. Head computed tomography and magnetic resonance imaging of brain were suspicious for a hemorrhagic mass located in the left petroclival region, compressing the ventral pons. The mass was surgically resected and demonstrated acute intratumoral hemorrhage. Pathologic examination was consistent with chordoma. Conclusion: There are few previous reports of petroclival chordomas causing acute intracranial hemorrhage. To the authors’ knowledge, this is the first case of a petroclival chordoma presenting as acute intracranial hemorrhage in a pediatric patient. Although uncommon, it is important to consider chordoma when evaluating a patient of any age presenting with a hemorrhagic lesion of the clivus.

The utility of radioisotope cisternography in low CSF/volume syndromes compared to myelography:

Objective The objective of this report is to compare computed tomography (CT) and magnetic resonance (MR) myelography with radioisotope cisternography (RC) for detection of spinal cerebrospinal (CSF) leaks. Methods We retrospectively reviewed 12 spontaneous intracranial hypotension (SIH) patients; CT and RC were performed simultaneously. Three patients had MR myelography. Results CT and/or MR myelography identified CSF leaks in four of 12 patients. RC detected spinal leaks in all three patients confirmed by CT myelography; RC identified the CSF leak location in two of three cases, and these were due to osteophytic spicules and/or discs. RC showed only enlarged perineural activity. Only intrathecal gadolinium MR myelography clearly identified a slow leak from a perineural cyst. In eight remaining cases, the leak site was unknown; however, two of these showed indirect signs of CSF leak on RC. CSF slow leaks from perineural cysts were the most common presumed etiology; and the cysts were best visualized on myelography. Conclusion RC is comparable to CT myelography but has spatial limitations and should be limited to atypical cases.

An atypical case of Canavan disease with stroke-like presentation.

BACKGROUND Canavan disease is an autosomal recessive leukodystrophy caused by a deficiency of aspartoacylase. The disease has a severe course, with death occurring in the first few years of life. Atypical patients with mild courses have been reported, but acute presentations similar to stroke have not been well described. PATIENT DESCRIPTION We present a boy who presented at 4 months of age with seizures after an episode of cardiopulmonary arrest is discussed. RESULTS He was initially thought to have an ischemic watershed stroke based on his initial clinical presentation and magnetic resonance imaging. However, biochemical and follow-up radiologic evaluation were consistent with mild Canavan disease. DNA sequencing of the ASPA gene indicated one known mutation (A305E) and a novel mutation, L30V. Follow-up magnetic resonance imaging did not reveal the atrophy which would have been expected with watershed ischemia. Magnetic resonance spectroscopy demonstrated elevated N-acetyl aspartate to creatinine and N-acetyl aspartate to choline ratios. At 4 years of age, he was normocephalic, with mild clumsiness, speech delay, and seizures. CONCLUSIONS This childs unusual acute presentation, along with his prolonged mild course, raises questions about the relationship between biochemical signs of abnormal aspartoacylase function and clinical findings. This patient highlights the need for long-term clinical follow-up of children with mild Canavan disease to clarify the significance of these biochemical abnormalities.

Diagnostic imaging of intracranial metastasis.

1 In both asymptomatic and symptomatic patients, imaging of the brain has a primary role in the detection of brain metastases and is important for subsequent patient management and treatment. This article will focus on the routine and advanced imaging techniques used to diagnose and monitor treatment of both new and recurrent intracranial metastases. Specific imaging patterns and potential pitfalls in the discernment between intracranial metastatic disease and other brain masses, intracranial infections, and the effects of treatment will be discussed.

Ectopic external auditory canal and ossicular formation in the oculo-auriculo-vertebral spectrum

Ear abnormalities in oculo-auricular-vertebral spectrum commonly present with varying degrees of external and middle ear atresias, usually in the expected locations of the temporal bone and associated soft tissues, without ectopia of the external auditory canal. We present the unique imaging of a 4-year-old girl with right hemifacial microsomia and ectopic location of an atretic external auditory canal, terminating in a hypoplastic temporomandibular joint containing bony structures with the appearance of auditory ossicles. This finding suggests an early embryological dysfunction involving Meckel’s cartilage of the first branchial arch.

Evaluation of Gadolinium Deposition in the Brain After MR Arthrography

OBJECTIVE Although significant investigation has been done into the deposition of gadolinium in the brains of patients receiving IV gadolinium, there is little research concerning nonintravenous uses of gadolinium, specifically in conjunction with musculoskeletal MR arthrography. Although small in volume, intraarticular administration is an off-label use of gadolinium, necessitating careful scrutiny for patient safety. Thus, we investigated the relationship between intraarticular gadolinium administration during MR arthrography and the presence of intracranial gadolinium deposition on subsequent brain MRI. MATERIALS AND METHODS An institutional review board-approved retrospective study was performed of patients with no history of gadolinium exposure who underwent MR arthrography from 2006 to 2016 followed by an unenhanced brain MRI examination. ROIs were manually placed within bilateral dentate nuclei (DN), bilateral globus pallidi (GP), bilateral thalami, bilateral middle cerebral peduncles (MCP), and the central pons (CP) on T1-weighted sequences. The left and right ROIs were averaged, and ratios of signal intensity were calculated for DN/MCP, DN/CP, GP/MCP, GP/CP, thalamus/MCP, and thalamus/CP. Similar ROIs were placed and ratios calculated for age-matched control subjects who had a history of brain MRI but no prior gadolinium exposure. We used t testing to compare signal intensity ratios between patients and control subjects. RESULTS A total of 31 patients met the inclusion criteria. We found no significant difference in signal intensity between patients and control subjects for DN/MCP (p = 0.40), DN/CP (p = 0.76), GP/MCP (p = 0.51), GP/CP (p = 0.86), thalamus/MCP (p = 0.93), and thalamus/CP (p = 0.30). CONCLUSION No association was found between intraarticular gadolinium administration for MR arthrography and detectable gadolinium deposition within the brain.

Using flow feature to extract pulsatile blood flow from 4D flow MRI images

4D flow MRI images make it possible to measure pulsatile blood flow inside deforming vessel, which is critical in accurate blood flow visualization, simulation, and evaluation. Such data has great potential to overcome problems in existing work, which usually does not reflect the dynamic nature of elastic vessels and blood flows in cardiac cycles. However, the 4D flow MRI data is often low-resolution and with strong noise. Due to these challenges, few efforts have been successfully conducted to extract dynamic blood flow fields and deforming artery over cardiac cycles, especially for small artery like carotid. In this paper, a robust flow feature, particularly the mean flow intensity is used to segment blood flow regions inside vessels from 4D flow MRI images in whole cardiac cycle. To estimate this flow feature more accurately, adaptive weights are added to the raw velocity vectors based on the noise strength of MRI imaging. Then, based on this feature, target arteries are tracked in at different time steps in a cardiac cycle. This method is applied to the clinical 4D flow MRI data in neck area. Dynamic vessel walls and blood flows are effectively generated in a cardiac cycle in the relatively small carotid arteries. Good image segmentation results on 2D slices are presented, together with the visualization of 3D arteries and blood flows. Evaluation of the method was performed by clinical doctors and by checking flow volume rates in the vertebral and carotid arteries.