An assessment of radiology resident competency in identifying suppurative retropharyngeal lymphadenitis: an examination using the WIDI SIM platform.

BACKGROUND AND PURPOSE: Suppurative retropharyngeal lymphadenitis is a retropharyngeal space infection almost exclusively seen in the young (4-8 years old) pediatric population. It can be misdiagnosed as a retropharyngeal abscess, leading to unnecessary invasive treatment procedures. This retrospective study aims to assess radiology residents' ability to independently identify CT imaging findings and make a definitive diagnosis of suppurative retropharyngeal lymphadenitis in a simulated call environment. MATERIALS AND METHODS: The Wisdom in Diagnostic Imaging Emergent/Critical Care Radiology Simulation (WIDI SIM) is a computer-aided emergency imaging simulation proven to be a reliable method for assessing resident preparedness for independent radiology call. The simulation included 65 cases across various imaging modalities of varying complexity, including normal studies, with one case specifically targeting suppurative retropharyngeal adenitis identification. Residents' free text responses were manually scored by faculty members using a standardized grading rubric, with errors subsequently classified by type. RESULTS: A total of 543 radiology residents were tested in three separate years on the imaging findings of suppurative retropharyngeal lymphadenitis using the Wisdom in Diagnostic Imaging simulation web-based testing platform. Suppurative retropharyngeal lymphadenitis was consistently underdiagnosed by radiology residents being tested for call readiness irrespective of the numbers of years in training. On average, only 3.5% of radiology residents were able to correctly identify suppurative retropharyngeal lymphadenitis on a contrast-enhanced computed tomography (CT). CONCLUSIONS: Our findings underscore a potential gap in radiology residency training related to the accurate identification of suppurative retropharyngeal lymphadenitis, highlighting the potential need for enhanced educational efforts in this area.

An Objective Study of Anatomic Shifts in Intracranial Hypotension Using Four Anatomic Planes.

PURPOSE: Intracranial hypotension (IH) often remains undetected using current MR diagnostic criteria. This project aims to demonstrate that central incisural herniation is highly effective in helping to make this diagnosis. MATERIALS AND METHODS: Magnetic resonance imaging (MRI) was analyzed in 200 normal and 81 clinically known IH patients. MRI reference lines approximating the plane of the incisura, the plane of the diaphragma sella, the plane of the foramen magnum, and the plane of the visual pathway were utilized to measure the position of selected brain structures relative to these reference lines. RESULTS: All IH patients had highly statistically significant (p < 0.0001) measurable evidence of downward central incisural herniation when compared to normal controls. The first of the important observations was a downward shift of the mammillary bodies, which shortened the midsagittal width of the interpeduncular fossa cistern. A concurrent downward shift and deformity of the tuber cinereum accompanied the mammillary body shift. The second essential observation was an abnormal clockwise rotation of the long axis of the visual pathway. A severity grading system is proposed based on the extent of these shifts as well as secondary shifts of the brain stem, splenium, and cerebellar tonsils. CONCLUSION: This study objectively delineates the anatomic shifts of brain structures adjacent to the incisura and foramen magnum. This methodology is sufficient to recognize the features of IH and to stratify the spectrum of IH findings into a functional grading system for quantifying the results of interventional therapy.

The hippocampus: detailed assessment of normative two-dimensional measurements, signal intensity, and subfield conspicuity on routine 3T T2-weighted sequences.

PURPOSE: The hippocampus has a critical role in many common disease processes. Currently, routine 3 Tesla structural MRI is a mainstay of clinical diagnosis. The goal of our study is to evaluate the normal variability in size and/or conspicuity of the hippocampal subcomponents in routine clinical 3 Tesla high-resolution T2-weighted images to provide a basis for better defining pathological derangements. Additionally, we utilize diffusion data acquired from a 17.6 Tesla MRI of the hippocampus as a benchmark to better illustrate these subcomponents. METHODS: The hippocampus was retrospectively assessed on 104 clinically normal patients undergoing coronal T2-weighted imaging. The conspicuity of the majority of hippocampal subcomponents was assessed in each portion of the hippocampus. Additionally, easily applicable cross-sectional measurements and signal intensities were obtained to evaluate the range of normal, as well as inter- and intra-subject variability. RESULTS: The normal range of cross-sectional measurements of the hippocampal subcomponents was calculated. There was minimal side-to-side variability in cross-sectional measurements of hippocampal subcomponents (< 5%) with the exception of the subiculum (R>L by 8.3%) and the CA4/DG (R>L by 5.8%). The internal architecture showed high variability in visibility of subcomponents between different segments of the hippocampus. CONCLUSIONS: Confident clinical assessment of the hippocampus requires a thorough knowledge of hippocampal size and signal, but also the internal architecture expected to be seen. The data provided in this study will provide the reader with vital information necessary for distinguishing a normal from abnormal exam.

Can standard magnetic resonance imaging reliably distinguish recurrent tumor from radiation necrosis after radiosurgery for brain metastases? A radiographic-pathological study.

OBJECTIVE: Stereotactic radiosurgery is a commonly used treatment method in the management of metastatic brain tumors. When lesions enlarge after radiosurgery, it may represent tumor regrowth, radiation necrosis, or both. The purpose of this study was to determine whether standard magnetic resonance imaging (MRI) sequences could reliably distinguish between these pathological possibilities. METHODS: A total of 619 patients, reported in a previous study, were treated with radiosurgery for metastatic brain tumors. Of those patients, 59 underwent subsequent craniotomy for symptomatic lesion enlargement. Of those 59 patients, 32 had complete preoperative MRI studies as well as surgical pathology reports. The following MRI features were analyzed in this subset of patients: arteriovenous shunting, gyriform lesion or edema distribution, perilesional edema, cyst formation, and pattern of enhancement. A novel radiographic feature, called the lesion quotient, which is the ratio of the nodule as seen on T2 imaging to the total enhancing area on T1 imaging, was also analyzed. RESULTS: Sensitivity, specificity, and predictive values were computed for each radiographic characteristic. Lesions containing only radiation necrosis never displayed gyriform lesion/edema distribution, marginal enhancement, or solid enhancement. All lesions exhibited perilesional edema. A lesion quotient of 0.6 or greater was seen in all cases of recurrent tumor, a lesion quotient greater than 0.3 was seen in 19 of 20 cases of combination pathology, and a lesion quotient of 0.3 or less was seen in 4 of 5 cases of radiation necrosis. The lesion quotient correlated with the percentage of tumor identified on pathological specimens. CONCLUSION: The lesion quotient appears to reliably identify pure radiation necrosis on standard sequence MRI. Other examined radiographic features, including arteriovenous shunting, gyriform lesion/edema distribution, enhancement pattern, and cyst formation, achieved 80% or greater predictive value but had either low sensitivity or low specificity.

Controlled clinical trial of dichloroacetate for treatment of congenital lactic acidosis in children.

OBJECTIVE: Open-label studies indicate that oral dichloroacetate (DCA) may be effective in treating patients with congenital lactic acidosis. We tested this hypothesis by conducting the first double-blind, randomized, control trial of DCA in this disease. METHODS: Forty-three patients who ranged in age from 0.9 to 19 years were enrolled. All patients had persistent or intermittent hyperlactatemia, and most had severe psychomotor delay. Eleven patients had pyruvate dehydrogenase deficiency, 25 patients had 1 or more defects in enzymes of the respiratory chain, and 7 patients had a mutation in mitochondrial DNA. Patients were preconditioned on placebo for 6 months and then were randomly assigned to receive an additional 6 months of placebo or DCA, at a dose of 12.5 mg/kg every 12 hours. The primary outcome results were (1) a Global Assessment of Treatment Efficacy, which incorporated tests of neuromuscular and behavioral function and quality of life; (2) linear growth; (3) blood lactate concentration in the fasted state and after a carbohydrate meal; (4) frequency and severity of intercurrent illnesses and hospitalizations; and (5) safety, including tests of liver and peripheral nerve function. OUTCOME: There were no significant differences in Global Assessment of Treatment Efficacy scores, linear growth, or the frequency or severity of intercurrent illnesses. DCA significantly decreased the rise in blood lactate caused by carbohydrate feeding. Chronic DCA administration was associated with a fall in plasma clearance of the drug and with a rise in the urinary excretion of the tyrosine catabolite maleylacetone and the heme precursor delta-aminolevulinate. CONCLUSIONS: In this highly heterogeneous population of children with congenital lactic acidosis, oral DCA for 6 months was well tolerated and blunted the postprandial increase in circulating lactate. However, it did not improve neurologic or other measures of clinical outcome.

Neonatal hypothalamic hamartoma: a differentiating nonlethal hamartoblastoma.

The authors report on a patient with a large hypothalamic hamartoma with a cleft lip and palate and seizures. Neuroimaging revealed a large extraaxial, intradural mass in the prepontine and interpeduncular cisterns with significant distortion of the brainstem. A stereotactic transfontanel needle biopsy revealed a cellular lesion that contained immature-appearing neuroepithelial cells consistent with prior descriptions of hypothalamic hamartoblastoma. While having a low level of proliferation by Ki67 (MIB-1) labeling, the lesion also contained evidence of neuronal maturation, with many cells expressing neuronal nuclear antigen as observed during immunohistochemical analysis. Further clinical evaluation revealed no other significant congenital abnormalities, and the patient was discharged home. Outpatient follow up has continued for 2 years and the patient has been doing well, requiring no further treatment. This case illustrates that, despite its immature and proliferative histological appearance, this rare neonatal mass can be regarded as a "differentiating" hypothalamic hamartoma and can have a favorable prognosis.

Cerebral edema in childhood diabetic ketoacidosis: natural history, radiographic findings, and early identification.

OBJECTIVE: Children who develop cerebral edema (CE) during diabetic ketoacidosis (DKA) exhibit definable signs and symptoms of neurological collapse early enough to allow intervention to prevent brain damage. Our objective was to develop a model for early detection of CE in children with DKA. RESEARCH DESIGN AND METHODS: A training sample of 26 occurrences of DKA complicated by severe CE and 69 episodes of uncomplicated DKA was reviewed. Signs of neurological disease were incorporated into a bedside evaluation protocol that was applied to an independent test sample of 17 patients previously reported to have developed symptomatic CE during treatment for DKA. Head computed tomograms and their reports were reviewed. RESULTS: The protocol allowed 92% sensitivity and 96% specificity for the recognition of CE sufficiently early for intervention. The diagnostic criteria were fulfilled in two temporal patterns, defining early- and late-onset CE. Although initial computed tomograms were often normal, the findings also included diffuse CE and focal brain injury, the latter only in patients with an early onset of abnormal neurological signs. CONCLUSIONS: CE may occur in the absence of acute changes on head computed tomograms. Early detection of CE at the bedside using an evidence-based protocol permits intervention in time to prevent permanent brain damage.

Peripheral third cranial nerve enhancement in multiple sclerosis.

Cranial nerve III dysfunction in multiple sclerosis (MS) is uncommon. Seven cases of isolated cranial nerve III paresis associated with MS have been reported in the English-language literature. MR imaging was obtained in five cases demonstrating lesions within the midbrain. We present the detailed clinical and MR imaging findings of a young woman with MS and an isolated, painful pupil involving complete left cranial nerve III palsy. Initial MR imaging showed isolated enhancement of the cisternal portion of the cranial nerve III, suggesting that peripheral nervous system involvement may develop as part of the disease process in some patients with MS.

Corticosteroid treatment of mitochondrial encephalomyopathies.

BACKGROUND: Mitochondrial encephalopathy with lactic acidosis and stroke-like symptoms (MELAS) is a multisystem disorder characterized by stroke-like episodes, seizures, dementia, headaches,evidence of mitochondrial myopathy. Lactic acidosis and ragged red fibers are often present. A variety of therapies have been used with inconclusive and disappointing results. There have been very few cases of MELAS reported as corticosteroid responsive. SUMMARY: A 27-year-old healthy man was hospitalized with recurrent generalized tonic-clonic seizures, intractable headaches, and stroke-like symptoms. These symptoms improved after the initiation of corticosteroid treatment. Multiple attempts to taper corticosteroids were followed by clinical relapse. Genetic testing in this patient revealed a point mutation at nt 3243 of the mitochondrial tRNA gene, confirming the diagnosis of MELAS. The patient died 1 year later after an episode of status epilepticus. Corticosteroid therapy in individual MELAS patients has been associated with clinical improvement. Discrepancy exists with regard to corticosteroid type, dose, route of administration, length of therapy, patient population, and clinical and metabolic parameters to follow during corticosteroid therapy. CONCLUSIONS: Corticosteroid therapy may be beneficial during acute exacerbation of MELAS.