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Biomedical subjects

D M Yousem

Publications and source records attributed to D M Yousem.

At least 73 records · Page 4Linked to original sources
PubMed1995

Cervical thorium dioxide granuloma ('thorotrastoma').

An elderly woman had an expanding cervical mass that entrapped and compressed the adjacent cranial nerves, blood vessels, and muscles. The mass was dense on radiographs, extended from the skull base to low neck in the prevertebral and parapharyngeal tissues, and showed mixed intensity on MR. A previous direct carotid arteriogram with thorium dioxide as the contrast agent suggested the histologically proved diagnosis of a cervical thorium dioxide granuloma ("thorotrastoma").

Diagnosis, Differential↗
PubMed1995

Thyroid and parathyroid gland pathology. Role of imaging.

There are many imaging modalities available for studying thyroid and parathyroid masses. For the thyroid gland, the demonstration of a hyperfunctioning or purely cystic mass by scintigraphy and ultrasound reassures that a palpable nodule is not cancer. Solitary, cold, or solid nodules often requires biopsy because of suspicion of malignancy. Metabolic and inflammatory disorders are imaged best with nuclear medicine studies whereas congenital thyroid lesions are evaluated best with computed tomography or MR imaging. In the search for a parathyroid adenoma, MR imaging and technetium-99m sestamibi studies appear to be most accurate, but because of its low cost, ultrasound has a favorable role. In previously operated patients with persistent hyperparathyroidism, MR imaging is probably most useful, but multiple imaging studies may be needed for definitive localization of adenomas.

Humans↗
PubMed1994

White matter changes are correlated significantly with radiation dose. Observations from a randomized dose-escalation trial for malignant glioma (Radiation Therapy Oncology Group 83-02).

BACKGROUND: A Phase I/II randomized dose-seeking trial was performed to document the severity, time course, and significance of white matter changes seen on serial imaging scans (magnetic resonance imaging, computed tomography) associated with bis-chlorethyl nitrosourea (BCNU) and hyperfractionated cranial irradiation. METHODS: Long term survivors (> or = 18 months) were identified from a prospective randomized dose-escalation Phase I/II trial designed to evaluate twice-daily radiotherapy for supratentorial high grade malignant gliomas. All scans were reviewed by a neuroradiologist who had no information about the prescribed dose and fractionation. In the trial, patients were assigned to receive 64.8 Gy, 72.0 Gy, 76.8 Gy, or 81.4 Gy (all fractionated as 1.2 Gy twice a day [bid]), or 48.0 Gy or 54.4 Gy (both in 1.6-Gy bid fractions). Bis-chlorethyl nitrosourea was administered every 8 weeks for 1 year. Of 747 randomized patients, 177 had analyzable scans. The scans reviewed were those acquired preoperatively, immediately postoperatively, 3, 6, 12, and 18 months after radiotherapy. Radiographic endpoints included no white matter change (Grade 0), minimal patchy white matter foci (Grade 1), start of confluence of white matter disease (Grade 2), large confluent areas (Grade 3), confluence with cortical/subcortical involvement (Grade 4), leukoencephalopathy (Grade 5), and possible necrosis (Grade 6) according to the classification of F. Fazekas et al. The effects were scored relative to the baseline preoperative scans. The dose pairs of 48 Gy and 54.4 Gy, 64.8 Gy and 72 Gy, and 76.8 Gy and 81.4 Gy were grouped together for analysis (low, intermediate, and high dose, respectively). Toxicity was analyzed in three ways: Grade 2 or worse, Grade 3 or worse, and Grade 6. RESULTS: Grade 2 or worse changes were observed in 26.6, 27.6, and 40.4% of patients in the low, intermediate, and high dose groups, respectively. Grade 3 or worse changes were observed in 8.3, 20.0, and 36.5% of patients in the low, intermediate, and high dose groups, respectively. Grade 6 changes were observed in 1.6, 4.6, and 19.2% of patients in the low, intermediate, and high dose groups, respectively. No statistically significant differences were observed among treatment groups when toxicity was evaluated as Grade 2 or worse. For toxicity of Grade 3 or worse, an chi-square test revealed P values of 0.04 (low vs. intermediate dose), 0.09 (intermediate vs. high dose), and 0.0005 (low vs. high dose). With the endpoint of possible necrosis (Grade 6), P values were 0.21 (low vs. intermediate dose), 0.05 (intermediate vs. high dose), and 0.003 (low vs. high dose). The median time to radiographic appearance of an effect (15 months) was not influenced by total dose or fraction size. CONCLUSIONS: A well described toxicity scale for white matter injury was applied successfully to patients with malignant glioma treated with definitive irradiation. Severe white matter changes continued to increase significantly as the total dose of hyperfractionated cranial irradiation was escalated. The time to onset of the white matter abnormalities appeared to be independent of dose. An ongoing Radiation Therapy Oncology Group study will allow correlation of white matter injury with prospective neuropsychometric testing.

Brain↗
PubMed1994

MR of cervical lymph nodes: comparison of fast spin-echo and conventional spin-echo T2W scans.

PURPOSE: In order to explore the utility of fast spin-echo techniques in the neck, 50 consecutive conventional spin-echo (CSE) long TR examinations were compared with 50 consecutive fast spin-echo (FSE) long TR scans for cervical lymph nodes. MATERIALS AND METHODS: Standard CSE examinations used parameters of 2200/80/1 (TR/TE/excitations), 256 x 128 matrix, 5 mm thick with interslice gaps between 1 and 2.5 mm. FSE studies were employed with TR of 4000/80/2, 256 x 192 matrix, fat suppression and 5 mm contiguous slices. Standard T1-weighted examinations and clinical correlation were used as proof of nodal presence. RESULTS: Overall vascular flow artefacts, patient motion artefacts, and image quality were comparable between the two techniques. Lymph node detectability was superior with FSE scans (P < 0.05). Typical time saved was approximately 4.5 min with FSE, despite the use of larger matrices, contiguous slices and twice the excitations. CONCLUSION: FSE is a competitive technique to CSE images in the neck, yielding similar quality images with higher resolution, reduced scan time, and improved lymph node detectability.

Artifacts↗
PubMed1994

Head and neck neoplasms: magnetization transfer analysis.

PURPOSE: Magnetization transfer (MT) imaging enables analysis of the contribution of restricted motion protons in the macromolecular pool to magnetic resonance (MR) signal intensity. The authors undertook this study to determine whether MT ratios (MTRs) could be used to predict pathologic characteristics of head and neck neoplasms. MATERIALS AND METHODS: Fifty-four patients with pathologically proved neoplasms (squamous cell carcinomas, n = 33; non-squamous cell carcinomas, n = 11; benign masses, n = 10) underwent MT imaging. MTRs were correlated with pathologic findings. RESULTS: No statistically significant correlations were noted between MTRs and degree of differentiation, keratinization, cells per high-power field, and rate of mitosis. Statistically significant differences were found between MTRs of malignancies and muscle (P < .01), cerebrospinal fluid (P < .001), fat (P < .001), and benign neoplasms (P < .001). MTRs of muscle were higher than those of benign, squamous cell, and non-squamous cell neoplasms. CONCLUSION: MT imaging shows promise in differentiation of benign from malignant head and neck neoplasms. No statistically significant differences in MTRs were noted among malignancies.

Carcinoma, Squamous Cell↗
PubMed1994

Neuroimaging in patients with olfactory dysfunction.

This review summarizes neuroimaging findings in patients with olfactory dysfunction. Neuroimaging techniques offer a valuable means for evaluating and distinguishing disorders of olfaction. The new or refined techniques make it possible to pinpoint the anatomic and pathologic changes of many disorders of the sinonasal cavity and brain that cause olfactory deficits. From an anatomic point of view, the causes of olfactory deficits generally can be classified as peripheral or central (intracranial). In the assessment of the peripheral causes, CT and MR imaging reveal anatomic information and structural changes, enable a differential diagnosis, and provide a road map for surgical intervention. In the evaluation of the central causes, MR imaging, positron emission tomography, or single-photon emission computed tomography can provide the links between olfactory dysfunction and structural or functional changes in the brain.

Brain Diseases↗
PubMed1994

Lhermitte-Duclos disease and Cowden's syndrome in an adolescent patient. Case report.

Recent reports of seven cases of Lhermitte-Duclos disease occurring in adult patients with Cowden's syndrome (multiple hamartoma syndrome) strongly suggest that Lhermitte-Duclos disease is one of the types of neoplasia that characterize this syndrome. A case of Lhermitte-Duclos disease is reported in a 16-year-old girl with craniomegaly, choroidal hamartoma, and conjunctival papilloma of the right eye, and a history of bilateral multinodular adenomatous goiter and cystic hygroma. These findings strongly suggest a diagnosis of Cowden's syndrome. Although the syndrome traditionally has been defined by mucocutaneous criteria, it typically also involves hamartomas and neoplasia of internal organs, most commonly in the thyroid, breast, and female genitourinary tract. Because the mucocutaneous features may develop several decades after birth, the present case both supports the previously reported association between Lhermitte-Duclos disease and Cowden's syndrome and highlights the need for long-term follow-up monitoring of a pediatric patient with Lhermitte-Duclos disease because of the risk of malignancies associated with Cowden's syndrome.

Adolescent↗
PubMed1994

MR of mandibular invasion in patients with oral and oropharyngeal malignant neoplasms.

PURPOSE: To investigate whether MR imaging is an accurate means of assessing mandibular invasion in patients with carcinoma. METHODS: We retrospectively studied the MR scans of 22 patients with pathologic or surgical confirmation of mandibular invasion from oral and oropharyngeal cancers. The MR images were blindly analyzed using primary criteria of: (a) cortical breakdown, (b) replacement of bone marrow fat, or (c) gadopentetate dimeglumine enhancement of a mass at the bone marrow defect. Secondary criteria of: (a) contiguous soft-tissue mass, and (b) mass on both sides of the mandibular cortex were also examined. Mandibular invasion was graded as periosteal/cortical, medullary, or no invasion. RESULTS: Primary positive findings of cortical breakdown and abnormal bone marrow signal were highly sensitive (100%) for periosteal/cortical invasion and medullary involvement, respectively. However, a high rate of false-positive studies hampered the MR accuracy, which fell into the 73% to 77% range. A negative MR study was highly predictive, but a positive study was less valuable. Gadolinium enhancement added little to the MR study's accuracy. False-positive studies mainly occurred in the setting of prior irradiation, osteoradionecrosis, and odontogenic infections. CONCLUSIONS: MR imaging is a sensitive method for detecting mandibular invasion but has a low positive predictive value. A negative study virtually excludes cortical/periosteal or bone marrow invasion.

Adipose Tissue↗
PubMed1994

Frequency of unexplained meningeal enhancement in the brain after lumbar puncture.

PURPOSE: To examine the hypothesis that lumbar puncture alone may cause meningeal enhancement in the brain. METHODS: We prospectively reviewed the brain MR examinations of all patients from a 6-month period who were studied within 1 month after lumbar puncture. We also retrospectively reviewed all cases of dural-arachnoidal enhancement in the brain from the preceding 18-month period. RESULTS: In the prospective group, only one case out of 97 enhanced brain MR examinations after lumbar puncture did not have a clear cause for dural-arachnoidal enhancement. In the retrospective group, only one case out of 11 with enhancement was not clearly explained. CONCLUSIONS: Dural-arachnoidal enhancement in the brain after lumbar puncture is uncommon, if it occurs at all, and lumbar puncture as a cause of enhancement should be considered a rare diagnosis of exclusion.

Adult↗
PubMed1994

Magnetization transfer imaging of the head and neck: normative data.

PURPOSE: To determine magnetization transfer ratios for normal head and neck structures so that evaluation of disease will be possible. METHODS: Two-dimensional magnetization transfer imaging was performed in 12 healthy volunteers and 20 patients. We used a repetition time of 500, echo time of 12, 20 degrees flip angle, and a magnetization transfer pulse offset from the resonance frequency of water by 2000 Hz (pulse duration 19 milliseconds, waveform area approximately 10 times greater than that of a 90 degree pulse). Magnetization transfer ratios (1 - [intensity after suppression/intensity before suppression]) were calculated for normal structures. RESULTS: The magnetization transfer ratio of facial muscles (0.54) was equivalent to that of tongue muscles (0.54). These values exceeded those of parotid (0.39) and submandibular glands (0.41). Fat (0.07) and cerebrospinal fluid (0.05) had negligible transfer. CONCLUSION: Magnetization transfer imaging is a simple and effective means of studying the contribution of macromolecular protons to the MR image. Normal neck structures show a wide range of magnetization transfer rates, maximal for muscle and minimal for cerebrospinal fluid and fat.

Adult↗
PubMed1994

Superficial siderosis of the central nervous system: an underdiagnosed cause of sensorineural hearing loss and ataxia.

Superficial siderosis of the central nervous system (CNS) is a rare but ultimately fatal disorder characterized by progressive hearing loss, ataxia, and dementia. Symptoms are caused by the deposition of hemosiderin in the CNS as a result of recurrent or persistent extravasation of blood into the cerebrospinal fluid. Sites most commonly involved include the cerebellum, brain stem, and eighth cranial nerve. In the past, diagnosis was most often made at autopsy, and this may account for the lack of reported cases in the otolaryngologic literature and the presumed rarity of the disorder. Now, diagnosis is confirmed by characteristic magnetic resonance imaging findings and treatment is targeted toward the source of bleeding. The diagnosis of superficial CNS siderosis should be entertained in all patients presenting with sensorineural hearing loss and ataxia.

Aged↗
PubMed1993

Imaging of sinonasal inflammatory disease.

Changes in imaging sinonasal inflammatory disease have paralleled changes in the treatment of chronic sinusitis. As functional endoscopic sinus surgery has become a more widespread technique, coronal computed tomography (CT) has become the primary imaging modality, replacing plain radiography. Knowledge of the plethora of sinonasal anatomic variations and the inherent surgical implications is critical to the interpretation of the CT scans and to the safe performance of endoscopic surgery. Currently, the role of magnetic resonance imaging is restricted to the evaluation of complicated sinusitis, intraorbital and intracranial manifestations of aggressive sinusitis, and sinonasal neoplasms.

Humans↗
PubMed1992

Central nodal necrosis and extracapsular neoplastic spread in cervical lymph nodes: MR imaging versus CT.

Computed tomographic (CT) scans and magnetic resonance (MR) images obtained in 24 patients with cervical lymphadenopathy were retrospectively and blindly evaluated by two readers for the presence of central nodal necrosis (CNN) and extracapsular nodal spread (ENS). The CT studies were all enhanced, and the MR images were obtained with short repetition time (TR)/echo time (TE), long TR/double echo, and enhanced short TR/TE fat-suppressed sequences. Each MR imaging sequence was interpreted separately and then collectively. Sixty lymph nodes were identified with CT. Sensitivity for CNN was 16%-67% with the unenhanced MR pulse sequences, 50% with enhanced sequences, and 83%-100% with CT. The most accurate reading of MR images for CNN was with the unenhanced T1-weighted and T2-weighted images (86%-87%); the accuracy of CT was 91%-96%. The accuracy of MR imaging for detecting ENS was maximal with T1-weighted images (78%-90%). Gadolinium-enhanced, fat-suppressed images did not improve accuracy in evaluating CNN or ENS. CT is currently more accurate than unenhanced or enhanced MR imaging in detecting CNN or ENS.

Carcinoma, Squamous Cell↗
PubMed1992

Inverted papilloma: evaluation with MR imaging.

The authors examined the magnetic resonance (MR) appearance of inverted papillomas to determine if this histologically benign lesion could be distinguished from malignancies of the sinonasal cavity. MR images in 10 patients with histologically proved inverted papilloma were retrospectively reviewed. The signal intensity of inverted papillomas on short repetition time (TR) images was iso- to slightly hypertintense to muscle in all 10 patients. Inverted papillomas had intermediate signal intensity on the long TR/echo time (TE) images. The tumors were iso- or slightly hypointense to fat on long TR/short TE images. In the seven patients who received gadopentetate dimeglumine, all inverted papillomas showed solid inhomogeneous enhancement. A review of eight sinonasal malignancies showed no distinctive signal intensity or enhancement characteristics to help differentiate inverted papillomas from various malignant tumors. The authors conclude that there is no signature MR appearance for the benign inverted papilloma. The main utility of MR imaging is in defining the extent of the lesion.

Adipose Tissue↗