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Biomedical subjects

L A Loevner

Publications and source records attributed to L A Loevner.

At least 37 records · Page 2Linked to original sources
PubMed1998

Spontaneous thrombosis of a basilar artery traumatic aneurysm in a child.

Traumatic aneurysms are rare and occur most commonly in young adults; however, the relative frequency in the pediatric population is high, owing to the low prevalence of congenital saccular aneurysms in children. Traumatic aneurysms typically involve the anterior circulation, and spontaneous thrombosis is uncommon; hence, surgery is usually necessary. We present a case of a posttraumatic aneurysm in a child that occurred after a fall from a large height and that spontaneously thrombosed.

Accidental Falls↗
PubMed1997

In situ hybridization for Aspergillus and Penicillium in allergic fungal sinusitis: a rapid means of speciating fungal pathogens in tissues.

Allergic fungal sinusitis (AFS) is a serious form of sinonasal fungal disease that is commonly associated with Aspergillus or Dematiaceous fungi. This study was performed to determine the incidence of Aspergillus or Penicillium in AFS by using in situ hybridization (ISH) for Aspergillus and Penicillium ribosomal RNA (rRNA). The Fontana-Masson melanin stain (FMMS) was also used to detect pigmented fungi (A. niger and Dematiaceous fungi). ISH was performed on 26 patients: 17 AFS cases with histologic evidence of fungi, 5 AFS cases without histologic evidence of fungi, 3 cases of invasive fungal sinusitis (IFS), and 1 case of fungus ball. Nine AFS specimens with histologic evidence of fungi were ISH positive. Positivity was also noted in two of three IFS cases, while no staining was seen in the fungus ball and in six AFS specimens without fungi demonstrable by silver stains. Six ISH-positive cases were FMMS positive, suggesting A. niger. Five ISH-negative AFS specimens were FMMS positive, suggesting Dematiaceous fungi. In summary, many AFS patients in our institution demonstrate Aspergillus/Penicillium organisms. Ancillary techniques may help identify fungi responsible for AFS if cultures are negative or not performed. ISH for rRNA is a useful means for rapidly speciating fungi in human tissues.

Adult↗
PubMed1997

Gliomas: correlation of magnetic susceptibility artifact with histologic grade.

PURPOSE: To determine whether magnetic susceptibility artifact on magnetic resonance (MR) images can be used to grade gliomas. MATERIALS AND METHODS: Twenty-nine patients with gliomas were prospectively examined with spin-echo T1-weighted MR imaging without and with contrast material enhancement, spin-echo or fast spin-echo T2- and proton-density-weighted MR imaging, and gradient-echo T2*-weighted MR imaging. Images were reviewed by two neuroradiologists, and susceptibility artifacts in the tumor region were graded. Heterogeneity, mass effect, contrast enhancement, and necrosis were also graded. Tumors were graded according to the World Health Organization classification. RESULTS: Increased susceptibility artifact was detected by at least one observer on gradient-echo MR images of 19 tumors. This feature was seen on only 10 of the spin-echo or fast spin-echo T2-weighted MR images of lesions. Fifteen neoplasms with increased susceptibility artifact detected on MR images by at least one observer were high-grade lesions (anaplastic astrocytoma or glioblastoma multiforme). Lesion susceptibility artifact detected on T2*-weighted MR images was associated with tumor grade (P < .05). CONCLUSION: Susceptibility artifacts on T2*-weighted gradient-echo MR images appear to be valuable in the preoperative evaluation of gliomas.

Adult↗
PubMed1997

Synovial sarcomas of the head and neck: MR findings.

OBJECTIVE: MR images of six synovial sarcomas of the head and neck were evaluated to determine their characteristic sites of origin, size, extent, intensity, and contrast enhancement. It was hoped that specific MR characteristics could be defined to suggest this entity. CONCLUSION: A nonmucosal head and neck mass that is isointense to gray matter on T1-weighted images and is well defined yet heterogeneous, with septations, hemorrhage, cysts, calcification, or multilocularity, should raise suspicion of a synovial sarcoma. Because the appearance of synovial sarcomas varies and other masses may appear similar, no specific imaging characteristics define the entity.

Adult↗
PubMed1997

Can radiologists accurately predict preepiglottic space invasion with MR imaging?

OBJECTIVE: The purpose of this study was to evaluate whether observers of MR imaging can accurately predict invasion of the preepiglottic fat (PEF) in patients with oropharyngeal and supraglottic laryngeal squamous cell carcinoma. MATERIALS AND METHODS: For 41 patients with pathologically proven squamous cell carcinoma of the oropharynx and supraglottic larynx, we retrospectively analyzed their MR images for the presence or absence of PEF neoplastic invasion. Unenhanced T1-weighted, fat-suppressed T2-weighted, and contrast-enhanced fat-suppressed T1-weighted scans were analyzed independently by two neuroradiologists who were unaware of the surgical findings. Proof of diagnosis was determined by pathologic analysis, intraoperative assessment, or both. RESULTS: Sixteen patients had neoplastic infiltration of the PEF. All infiltration was correctly predicted by the two observers of MR imaging, resulting in a sensitivity of 100%. Twenty-five patients had no invasion of the PEF by pathologic or surgical evaluation or both. Of these patients, negative findings were correctly predicted on MR imaging in 21 patients, whereas positive findings were incorrectly predicted on MR imaging in the remaining four patients, resulting in a specificity of 84% and an accuracy of 90%. In two of the four false-positive cases, effacement of the fat in the preepiglottic space by large tumors was mistaken for invasion. In a third patient, spread to the paraglottic space was mistaken for PEF extension. In the fourth false-positive case, glandular tissue along the ventral epiglottis may have been mistaken for tumor. The observers believed that unenhanced sagittal and axial T1-weighted scans were particularly useful because fat saturation artifacts may degrade T2-weighted and contrast-enhanced T1-weighted scans. CONCLUSION: Unenhanced T1-weighted MR images are highly sensitive for neoplastic infiltration of the preepiglottic space in patients with oropharyngeal and supraglottic laryngeal carcinoma who are at risk for such spread. Identification of PEF invasion is important because it affects prognosis and may affect surgical management.

Adipose Tissue↗
PubMed1997

Heterotopic brain in the pterygopalatine fossa.

Heterotopic brain outside the cranial vault is uncommon. It occurs most frequently in the nasal region, although rests elsewhere in the aerodigestive tract have been reported. We describe a case of heterotopic brain in the pterygopalatine fossa.

Biopsy↗
PubMed1997

MR of thoracic cord compression caused by epidural extramedullary hematopoiesis in myelodysplastic syndrome.

Spinal cord compression caused by extramedullary hematopoiesis is a rare complication of chronic anemic states, most frequently occurring in patients with beta-thalassemia. We report the MR appearance of extramedullary hematopoiesis resulting in cord compression in a patient with a myelodysplastic syndrome, which was isointense with the spinal cord on T1-weighted images and markedly hypointense on fast spin-echo T2-weighted images, and that demonstrated enhancement.

Aged↗
PubMed1997

Clinical and economic impact of incidental thyroid lesions found with CT and MR.

PURPOSE: To estimate the prevalence and the clinical and economic consequences of management strategies for thyroid lesions detected incidentally on cross-sectional imaging of the head and neck. METHODS: Two hundred consecutive CT scans and 200 consecutive MR images of the neck performed over a 1-year period in patients being examined for other purposes were reviewed retrospectively to determine the prevalence of unexpected thyroid lesions. After excluding patients with prior thyroidectomies, known thyroid disease, and inadequate examinations, 231 imaging studies were analyzed. RESULTS: Incidental thyroid lesions were originally reported in 14 (6%) of the 231 patients, but an additional 22 (9.5%) were found on retrospective review for a total of nearly 16% (36 of 231). Six of the 36 patients received further workup, consisting of nuclear medicine scintigraphy (n = 3), sonography (n = 3), thyroid function tests (n = 5), fine-needle aspiration (n = 4), and thyroid lobectomy (n = 1). Final diagnoses, obtained in four of the six patients, included three multinodular goiters and one follicular adenoma. Two patients, one with nondiagnostic findings at fine-needle aspiration and a second with normal thyroid function test results, are being followed up. The mean cost of the workup and treatment per examined patient was $1158. CONCLUSION: Incidental thyroid lesions are frequently present and often overlooked on cross-sectional images of the neck in patients being examined for other reasons. The cost of pursuing a workup of these lesions and their high prevalence in the population raise questions regarding appropriate management strategies.

Adenoma↗
PubMed1997

Adenoidal width and HIV factors.

PURPOSE: To determine the factors that correspond to adenoidal hypertrophy, often prominent in human immunodeficiency virus (HIV)-positive patients. METHODS: The sagittal T1-weighted MR images of 21 HIV-positive patients (age range, 25 to 50 years; mean, 37 years) and 21 healthy control subjects (age range, 24 to 55 years; mean, 35 years) were reviewed blindly and independently by two radiologists who measured the maximal dimension of the nasopharyngeal lymphoid tissue. Twenty-six additional HIV-positive patients were combined with the original 21 HIV-positive patients, and the hematologic studies of these 47 patients were compared with the adenoidal measurements to assess whether a relationship existed between nasopharyngeal prominence and hematocrit, white blood cell count, and CD4 count. RESULTS: Mean adenoidal width was 6.76 mm (SD, 5.82) in the HIV-positive population, but was only 3.36 mm (SD, 2.48) in the age-matched control group. Age and HIV status correlated with nasopharyngeal width measurements. No relationship between adenoidal width and hematocrit, CD4 count, or white blood cell count was evident. CONCLUSION: After correcting for age, we found that adenoidal lymphoid tissue is more abundant in HIV-positive persons than in control subjects. The hematologic ramifications of this finding remain uncertain.

Adenoids↗
PubMed1996

Neuropsychiatry of 18q- syndrome.

Our understanding of neuropsychiatric abnormalities in patients with deletions of the long arm of chromosome 18 (18q- syndrome) is based mainly on sporadic case reports. We characterized the neuropsychiatric phenotype in 27 patients across a wide age range (2-47 years) with breakpoints ranging from 18q22.3-18q21.2. Adaptive behavior scores (Vineland Composite) were significantly higher in females than in males (62 +/- 5 vs. 43 +/- 3). Intelligence ranged from borderline to severely deficient (IQ, 73- < 40), with academic achievement similarly impaired. Performance in specific neuropsychological functions, including attention, novel problem solving, memory, language, visuomotor integration, and fine motor dexterity, was consistently in the moderately-to-severely impaired range. Behavioral problems were common in both sexes, including aggressivity, hyperactivity, and temper tantrums. Contrary to the few previous reports, we found no evidence of psychosis in any patients. In a subset of patients selected on the basis of no prior knowledge of behavioral problems, 1 of 16 patients (6%) had autism, as defined by the Autistic Diagnostic Interview--Revised (ADI-R) [Lord et al., 1994: J Autism Dev Disord 24:659-685]. Thus, the prevalence of autism in 18q- syndrome is probably no greater than that in other developmental disabilities with a similar level of cognitive impairment. In contrast to what has been believed since 18q- was first described 30 years ago, we found no relationship between chromosome deletion size and any measure of cognition or behavior; nor were there any correlations between any of these measures with the presence or absence of abnormalities on MRI or somatosensory-evoked potentials.

Adaptation, Psychological↗
PubMed1996

Imaging of the thyroid gland.

The thyroid gland is critical in regulating metabolic functions including cardiac rate and output, lipid catabolism, skeletal growth, and oxygen and heat production. Thus, patients with hormonally active thyroid abnormalities present with wide-ranging symptoms, requiring an understanding of the gland's hormonal functions. Radiological imaging assesses the pathophysiological affects of abnormal thyroid function as well as important morphological features. Nuclear scintigraphy provides functional information about the gland, whereas cross-sectional imaging-including ultrasound, CT, and MR-provide adjunctive anatomic information. These modalities also provide information about related structures in the neck. The embryology, anatomy, and physiology of the thyroid are discussed; congenital, autoimmune, inflammatory, metabolic, and neoplastic diseases are reviewed; and the diagnostic utility of radiological imaging is addressed.

Autoimmune Diseases↗
PubMed1996

Imaging of the parathyroid glands.

Primary hyperparathyroidism resulting in hypercalcemia is the most common presentation of parathyroid pathology and usually is related to a parathyroid adenoma and, less commonly, to hyperplasia. Imaging of the parathyroid glands focuses on the detection of adenomas in patients with primary hyperparathyroidism. The role of imaging (as well as the modality used) for preoperative localization of the parathyroid glands continues to be controversial. The embryology, anatomy, and physiology of the parathyroid glands are reviewed. The diagnostic utility of radiological imaging-including ultrasonography, CT, MR imaging, and nuclear scintigraphy-are discussed, particularly as it pertains to the evaluation of primary hyperparathyroidism.

Diagnostic Imaging↗
PubMed1996

Primary malignant melanoma of the sinonasal cavity: MR imaging evaluation.

To evaluate the magnetic resonance (MR) imaging characteristics of primary malignant melanoma of the sinonasal cavity, T1- and T2-weighted MR images of 12 patients with primary sinonasal melanoma were retrospectively reviewed. Gadolinium-enhanced imaging was performed in seven cases. The MR images were compared with histopathologic results. There were seven melanotic melanomas and five amelanotic melanomas; hemorrhage was present in three melanotic and two amelanotic melanomas. The seven melanotic melanomas were hyperintense to gray matter on T1-weighted images (whether hemorrhage was present or not), consistent with the paramagnetic effect of melanin. Four of the five amelanotic melanomas had intermediate signal intensity on T1-weighted images; one was not detected. On T2-weighted images, all of the melanomas detected had intermediate though variable signal intensity compared with that of gray matter. On gadolinium-enhanced images, all cases demonstrated mild to moderate enhancement. The signal intensity of sinonasal melanoma appears to vary according to the histopathologic components of the tumor. High signal intensity within the lesion on T1-weighted images suggests the presence of melanin.

Aged↗
PubMed1996

Granular cell myoblastoma of the cervical esophagus: MR findings.

Granular cell myoblastomas are uncommon, typically benign tumors. Involvement of the esophagus is rare, and frequently they are asymptomatic. We report a granular cell myoblastoma involving the cervical esophagus in a patient who had paralysis of the true vocal cord and progressive dysphagia. At MR imaging, the circumscribed mass was hypointense on T1-weighted images and mildly hyperintense on T2-weighted images, with homogeneous contrast enhancement.

Adult↗
PubMed1995

Microscopic disease in normal-appearing white matter on conventional MR images in patients with multiple sclerosis: assessment with magnetization-transfer measurements.

PURPOSE: To assess for the presence of microscopic abnormalities in otherwise normal-appearing white matter on T2-weighted images in patients with multiple sclerosis (MS) by using magnetization-transfer (MT) measurements. MATERIALS AND METHODS: Twenty-three patients with MS and nine healthy control subjects underwent magnetic resonance (MR) imaging with a 1.5-T system. MT ratios (MTRs) were measured in 16 areas of normal-appearing white matter identified on conventional T2-weighted images in patients with MS. MTRs in the same white-matter locations in control subjects were determined. The two groups were compared. RESULTS: The mean whole-brain MTR of normal-appearing white matter in patients was 40.13% +/- 1.37 (standard deviation; range, 36.31%-42.09%); in control subjects, 42.93% +/- 0.95 (range, 41.62%-44.50%). The difference was statistically significant (P < or = .001). Except for the internal capsules, the difference in mean MTRs in each sublocation of the brain between patients and control subjects was statistically significant (P < or = .05). CONCLUSION: MT measurements are more sensitive than conventional MR imaging in the detection of abnormalities beyond the resolution of T2-weighted imaging.

Adult↗
PubMed1995

Characterization of multiple sclerosis plaques with T1-weighted MR and quantitative magnetization transfer.

PURPOSE: To investigate the relationship between the appearance of multiple sclerosis lesions identified on unenhanced T1-weighted images and their corresponding magnetization transfer ratios. METHODS: A total of 119 white matter lesions seen on T2-weighted images in 17 patients with multiple sclerosis were evaluated. Axial T1-weighted images were used to classify the lesions as isointense to white matter (10 lesions), hypointense to white matter but hyperintense to gray matter (44 lesions), hypointense to gray matter (59 lesions), and relatively isointense to cerebrospinal fluid (6 lesions). The magnetization transfer ratio of each lesion was calculated, and an average magnetization transfer ratio for each subcategory was determined. RESULTS: The magnetization transfer ratio values became progressively lower with increasing hypointensity of lesions on T1-weighted images. The average magnetization transfer ratio for lesions isointense to white matter, hypointense to white matter but hyperintense to gray matter, hypointense to gray matter, and relatively isointense to cerebrospinal fluid was 34.90 +/- 2.67 mean +/- SD), 30.93 +/- 3.57, 27.27 +/- 3.56, and 23.62 +/- 2.83, respectively. All groups were significantly different from each other. CONCLUSION: Lesions isointense to white matter exhibited higher magnetization transfer ratio values than lesions that were hypointense. These findings are consistent with relative preservation of the myelin structure in the former, perhaps indicating that these lesions are predominantly inflammatory (edematous) in nature. The proportionately lower magnetization transfer ratio values of lesions that appear progressively more hypointense on T1-weighted images may reflect varying degrees of demyelination, with increasing lesion hypointensity corresponding to more breakdown in the macromolecular structure. These results suggest that T1-weighted images may be useful in characterizing the underlying pathologic substrate in multiple sclerosis plaques.

Adult↗