Biomedical subjects
Publications and source records attributed to F J Hahn.
We report an unusual presentation of a dacryocystocele in a 3-day-old child, with clinical and novel MRI findings. The literature contains extensive CT documentation, but descriptions of the MRI appearances of dacryocystoceles are lacking. Although CT is the standard initial imaging modality, MRI can be helpful if there are questions as to the content of the lesion or a need for further anatomical characterization.
SUMMARY: We present an unusual case of a giant cell reparative granuloma arising from the left temporal lobe area of a 38-year-old man and provide clinical and MR findings. Current diagnosis and treatment options are also discussed.
OBJECTIVE: This retrospective study describes the phenotype associated with the single most common cause of genetic hearing loss. The frequency of childhood deafness is estimated at 1/500. Half of this hearing loss is genetic and approximately 80% of genetic hearing loss is nonsyndromic and inherited in an autosomal recessive manner. Approximately 50% of childhood nonsyndromic recessive hearing loss is caused by mutations in the connexin 26 (Cx26) gene (GJB2/DFNB1), making it the most common form of autosomal recessive nonsyndromic hearing loss with a carrier rate estimated to be as high as 2.8%. One mutation, 35delG, accounts for approximately 75% to 80% of mutations at this gene. METHODS: Hearing loss was examined in 46 individuals from 24 families who were either homozygous or compound heterozygous for Cx26 mutations. A subset of these individuals were examined for vestibular function, otoacoustic emissions, auditory brainstem response, temporal bone computed tomography, electrocardiography, urinalyses, dysmorphology, and thyroid function. RESULTS: Although all persons had hearing impairment, no consistent audiologic phenotype was observed. Hearing loss varied from mild-moderate to profound, even within the group of families homozygous for the common mutation 35delG, suggesting that other factors modify the phenotypic effects of mutations in Cx26. Furthermore, the hearing loss was observed to be progressive in a number of cases. No associations with inner ear abnormality, thyroid dysfunction, heart conduction defect, urinalyses, dysmorphic features, or retinal abnormality were noted. CONCLUSION: Newborns with confirmed hearing loss should have Cx26 testing. Cx26 testing will help define a group in which approximately 60% will have profound or severe-profound hearing loss and require aggressive language intervention (many of these patients will be candidates for cochlear implants).
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To accurately identify lumbosacral transitional vertebrae and disease location, cervicothoracic sagittal scout images were obtained in addition to the standard images used in magnetic resonance imaging studies of the lumbar spine, and vertebrae were counted down from C-2 rather than up from L-5. In 200 patients, these techniques revealed 24 transitional vertebrae (15 cases of sacralization of L-5 and nine cases of lumbarization of S-1).
A patient with an intracerebral hematoma and associated edema in the high right hemisphere parasagittal convexity had several episodes of apnea at night and during the day when she was asleep. On computed tomography (CT) scan, the hematoma demonstrated no evidence of brainstem compression. Sagittal magnetic resonance image (MRI), revealed the hematoma and edema mass resulted in central herniation with axial deformity of the brainstem. This is believed to be the cause of the apneic episodes. Treatment with mannitol and steroids promptly relieved the symptom.
We assessed the morphologic findings of the brain prospectively before and after cardiac surgery using magnetic resonance imaging. There were 12 patients with acyanotic and 6 with cyanotic heart disease. There were 2 deaths, and 1 patient did not have to undergo postoperative magnetic resonance imaging. The study group consisted of 15 patients completing both the preoperative and postoperative magnetic resonance imagings. All patients in the study group underwent moderate hypothermic cardiopulmonary bypass using a nonpulsatile membrane oxygenator. The mean (+/- SD) cardiopulmonary bypass time was 100 +/- 55 minutes. Ten of the preoperative studies were interpreted as normal. One third (5 of 15) of the patients showed ventriculomegaly and dilatation of the subarachnoid spaces on preoperative magnetic resonance images. Measurements of the preoperative and postoperative magnetic resonance images showed a postoperative increase in the bicaudate and third ventricular diameters. Four patients in the study group developed postoperative subdural hematomas. The subdural hematomas were small and caused no demonstrable mass effect on magnetic resonance imaging. One patient had a preoperative white matter infarction. There was 1 patient with a postoperative infarction.
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Explore the source record for details and available documents.
Explore the source record for details and available documents.
Hypothalamic hamartoma is the most common detectable cerebral lesion causing precocious puberty. Two histologically confirmed cases were studied by computerized tomography (CT) and magnetic resonance (MR) imaging. T2 weighted, sagittal MR images were superior to CT in delineating the tumor from surrounding grey matter. The lesion was isointense to grey matter on T1 weighted images allowing exclusion of other hypothalamic tumors. MR will undoubtedly become the imaging modality of choice in the detection of hypothalamic hamartoma.
High field MRI of the brain occasionally exhibits imaging artifacts; most artifacts are obvious and easily recognized, but some are subtle and mimic disease. A thorough understanding of brain MRI artifacts is important to avoid potential diagnostic pitfalls. Some imaging techniques or procedures could be utilized to remove or identify artifacts. These include additional projections, different pulse sequence, and 90 degree shift of phase-encoding gradient. The use of respiratory gating or cardiac gating may also improve image quality by reducing some of the motion-related artifacts.
MRI has undergone an incredibly rapid evolution, and technical advances are continually occurring. MRI allows for high resolution imaging that can clearly demonstrate a variety of degenerative processes of the spine. High-resolution MRI that gives detailed anatomic information, coupled with the use of MR contrast agents, promises to change our diagnostic approach significantly for degenerative disk disease of the spine.
Large, multiloculated abscesses can be difficult to drain percutaneously. The authors describe a technique for disrupting septations within an abscess cavity to provide more complete and effective drainage. It has been successfully performed in four patients.
Similar to all other medical imaging modalities, magnetic resonance imaging (MRI) has various artifacts. Some artifacts are easily recognizable such as motion, while some are not very obvious and even sometimes mimic pathologic conditions. These artifacts, if not differentiated, could easily become diagnostic pitfalls for radiologists and lead to erroneous conclusions. We have studied some of the imaging artifacts associated with a 1.5 tesla MRI scanner and report some cases who could become potential diagnostic pitfalls. Causes for these artifacts, although some not proven, are also presented.
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Artifacts on CT images have been observed since the introduction of CT scanners. Some artifacts have been corrected with the improvement of technology and better understanding of the image formation and reconstruction algorithms. Some artifacts, however, are still observable in state-of-the-art high-resolution scans. Many investigations on CT artifacts have been reported. Some artifacts are obvious and some are similar to patterns commonly associated with pathological conditions. The present report summarizes some of the causes of artifacts and presents some artifacts that mimic pathology on clinical scans of the head and spine. It is the intention of this report to bring these artifacts and potential pitfalls to the attention of the radiologists so that misinterpretation can be avoided.