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Biomedical subjects

D M Yousem

Publications and source records attributed to D M Yousem.

At least 109 records · Page 6Linked to original sources
PubMedDate not supplied

Evaluation of soft palate function with MRI: application to the cleft palate patient.

Magnetic resonance imaging was employed to evaluate soft palate function in four normal volunteers and four patients with surgically repaired cleft palate, using a GE Signa clinical scanner at 1.5 T and a custom designed receive coil with a sensitivity profile encompassing from the nasopharynx to the larynx. Midsagittal images were obtained using spoiled gradient recalled acquisition at steady state while the subject phonated the following sounds: (a) MMM, (b) SSS, (c) DAH, and (d) EEE. An image at rest with normal breathing was also obtained. The soft palate and its relationship to the airway and the posterior pharyngeal wall were clearly visualized in all cases. Phonation of the prescribed sounds demonstrated the normal range of soft palate motion. The images also depicted the ability of the soft palate to divert airflow to the nasopharynx. Interpretation of functional MRI may be of value in evaluation of surgical results, guidance of speech therapy, and surgical planning in the cleft palate patient. This noninvasive alternative to conventional methods of visualization provides advantages in resolution, repeatability, and patient comfort.

Adolescent↗
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MRI of carotid angiopathy after therapeutic radiation.

OBJECTIVE: Our goal was to assess whether significant secondary atherosclerotic changes from radiation can be detected on SE MR of the neck. MATERIALS AND METHODS: Pre- and postradiation MR scans of 16 patients with head and neck malignancies were studied randomly, independently, and blindly by two readers to determine the frequency of narrowing of the carotid arterial lumen and obliteration of the carotid space within the carotid sheath. RESULTS: Interval narrowing of either the common, internal, or external carotid artery lumen was seen in 108 of 192 (56%) of vessels evaluated on postradiation MR scans compared with preradiation studies. The differences in the grades of vessel luminal diameter were statistically significant (p < 0.05 for one reader and p < 0.0001 for the other reader). Among the 16 patients, 3 patients had vessels with a critical degree of stenosis, newly appearing on postradiation scans. Seven of 16 patients had diffuse obliteration of the planes within the carotid space. CONCLUSION: The incidence of accelerated atherosclerosis from therapeutic radiation may be greater than expected in nonirradiated patients. Magnetic resonance scans are an effective, noninvasive method for this type of follow-up.

Aged↗
PubMedDate not supplied

Gadolinium-enhanced fat-suppressed T1-weighted imaging of the head and neck: comparison of gradient and conventional SE sequences.

PURPOSE: The purpose of this study was to compare contrast-enhanced GRE and conventional SE (CSE) fat-suppressed T1-weighted techniques in the evaluation of head and neck lesions. A hybrid, opposed phase, frequency-selective, fat-suppressed fast multiplanar spoiled GRE (FMPSPGR) sequence was compared with a fat-suppressed CSE sequence. METHOD: Thirty-two patients with head and neck pathology were evaluated with both fat-suppressed CSE and FMPSPGR sequences. Regions of interest obtained by two viewers in consensus were used to establish contrast-to-noise (CNR) and signal-to-noise ratios for both sequences. Three neuroradiologists also independently reviewed the images for quality of fat suppression, lesion conspicuity, and potential pitfalls. RESULTS: The CNR of the FMPSPGR sequence was superior to that of the fat-suppressed CSE sequence. Subjectively, all three reviewers rated the FMPSPGR sequence as having fat suppression equal to or better than that in the CSE sequence in 94% of cases. Imaging times for the FMPSPGR sequence were 60-75% faster than those for the CSE sequence. CONCLUSION: Enhanced imaging of the head and neck region using an opposed phase, fat-suppressed GRE sequence results in improved fat suppression compared with the CSE technique, with substantial savings in imaging time.

Adult↗
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Overlooked metastatic lesions of the occipital condyle: a missed case treasure trove.

Radiologic images obtained in nine patients with known primary cancer and occipital or head and neck pain were retrospectively reviewed after having been initially interpreted as normal. Imaging studies included head computed tomography (CT) in five cases, brain magnetic resonance (MR) imaging in six cases, cervical spine CT and MR imaging in five cases, radiography in two cases, and scintigraphy in two cases. This reevaluation demonstrated lesions of the occipital condyles in all patients. Seven patients had unilateral occipital condyle masses, and two patients had bilateral condyle lesions. Lesions were found to either involve only the occipital condyle (n = 4), extend to the adjacent occipital bone (n = 3), or extend to the ipsilateral clivus (n = 2). Misinterpretation of radiologic examinations resulted in an average delay in diagnosis of 10 weeks from the onset of symptoms to definitive therapy (irradiation). It is important to evaluate the occipital condyles in all patients with occipital pain, especially those with cancer. Neoplastic disease involving the occipital condyles is not common; however, it is frequently missed at imaging. Careful review of unenhanced sagittal and axial T1-weighted MR images and of the inferior sections from axial head CT studies will make it possible to avoid this potential pitfall.

Aged↗
PubMedDate not supplied

Injection rates for neuroangiography: results of a survey.

BACKGROUND AND PURPOSE: Injection rates have attracted scrutiny because of an incident of an aneurysm rupturing during arteriography. We sought to determine the current injection rates for neuroangiography in the setting of aneurysm evaluation. METHODS: An e-mail survey was distributed to 90 neuroradiology program directors within the United States and Canada. The injection rates and total volumes of contrast material injected for the common carotid, internal carotid, and vertebral arteries were provided for an "average" adult individual evaluated for intracranial aneurysms. RESULTS: Sixty-three (70.0%) program directors replied to the survey. Of these, five perform hand injections only and provided approximate values. The mean injection rates (SD) and total volumes (SD) for common carotid arteries were 7.2 cm(3)/s (1.8) and 9.9 cm(3) (2.0), respectively; for internal carotid arteries, 5.8 cm(3)/s (1.4) and 7.9 cm(3) (1.5); and for vertebral arteries, 5.4 cm(3)/s (1.2) and 7.8 cm(3) (1.7). The modes (rate/total) for the common carotid, internal carotid, and vertebral arteries were 7/12, 6/8, and 5/8, respectively. Forty-eight (81.4%) of 59 respondents did not believe a reduction in current injection rates would lead to a diminution in complications of arteriography. CONCLUSION: The rates of injection of contrast material in the United States for neuroradiologic studies show great variability. It does not seem that reducing arteriographic complications is an impetus to reduce injection rates. The values in this survey can provide "industry norms" for injections in the common carotid, internal carotid, and vertebral arteries if these rates are challenged.

Canada↗
PubMedDate not supplied

Cervical spine disk herniation: comparison of CT and 3DFT gradient echo MR scans.

The purpose of this study was to compare CT and MR for the detection of cervical disk herniations. Nineteen patients suspected of harboring degenerative disk disease of the cervical spine underwent thin contiguous section CT myelography (CTM) and thin contiguous section three-dimensional Fourier transform (3DFT) gradient echo MR at 67 disk levels. Blinded readings of a high intensity CSF MR technique for the presence or absence of disk herniation were performed by three neuroradiologists. The intraobserver CT-MR concordances ranged from 84 to 89%. Using CTM as the paragon test, MR demonstrated a sensitivity of 79-91% and a specificity of 82-88% for disk herniation. Mean MR-CT concordance (86%) was nearly equivalent to that of CT-CT intraobserver concordance (88%). When consensus readings were considered, the MR-CT concordance (91%) was slightly higher than that of CT-CT intraobserver concordance (88%). We conclude that thin section 3DFT gradient echo MR with high intensity CSF is a reliable method to screen for degenerative disk disease in the cervical spine, since the agreement between MR and CTM is comparable with the intraobserver agreement of CTM.

Cervical Vertebrae↗
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Resectability issues with head and neck cancer.

Head and neck surgeons often rely on imaging to determine if a neoplasm is resectable. Many of the critical issues are outlined in the American Joint Committee on Cancer Staging Manual, wherein T4a and T4b head and neck cancers are defined as resectable and unresectable, respectively. Even within the T4a advanced resectable classification, there are critical determinants that define whether the surgical option is such that major morbidity and mortality could be expected. This review article examines the imaging literature to determine the accuracy and diagnostic criteria of different modalities for evaluating these critical T4a and T4b factors, which include the following: 1) arterial encasement, 2) prevertebral fascia involvement, 3) mediastinal infiltration, 4) tracheal and esophageal extension, 5) laryngeal cartilage penetration, 6) pre-epiglottic fat involvement, 7) dural spread, 8) bone (mandible/maxilla and skull base) infiltration, 9) perineural spread, 10) orbital involvement, and 11) brachial plexus invasion. For the most part, the studies find MR imaging with higher sensitivity but lower specificity than CT. An ever-increasing role for PET/CT is suggested. Imaging is of great value in the determination of resectability issues listed previously for head and neck cancers, with the possible exception of prevertebral fascia involvement.

Bone Neoplasms↗
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Integrated MR imaging and proton nuclear magnetic resonance spectroscopy in a family with an X-linked spastic paraparesis.

Seven members of a family with an X-linked spastic paraparesis syndrome were analyzed by MR imaging and stimulated echo, solvent-suppressed proton nuclear magnetic resonance spectroscopy. The MR scans of three symptomatic males and two asymptomatic females demonstrated abnormal signal in the supratentorial white matter. Each of these patients had a proton spectroscopic examination of a 2 X 2 X 2 cm voxel localized to the abnormal white matter of the centrum semiovale. The spectra demonstrated depression of N-acetyl aspartate/creatine, N-acetyl aspartate/choline, and creatine/choline ratios compared with normal control subjects. Additionally, these patients had abnormal elevations of amino acid resonances in the 2.1-3.0 ppm range. In a patient with symmetric white matter signal intensity abnormalities, an asymmetric spectroscopic study correlated with asymmetric symptoms. One asymptomatic family member with a normal MR study had abnormal metabolite ratio measurements. She was referred for further evaluation, since the proton spectrum suggested she may possess the affected gene. If the findings in this study are duplicated in other cases of hereditary dysmyelinating syndromes, we believe the integrated MR/proton nuclear magnetic resonance spectroscopy examination will be of benefit in evaluating and counseling families with familial dysmyelinating disorders.

Brain↗
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Degenerative narrowing of the cervical spine neural foramina: evaluation with high-resolution 3DFT gradient-echo MR imaging.

Conventional two-dimensional Fourier transform (2DFT) MR evaluation of osteophytic disease of the cervical neural foramina is limited by section thickness, signal-to-noise problems, and CSF flow artifacts. We evaluated the role of thin-section, high-resolution, gradient-refocused three-dimensional Fourier transform (3DFT) MR imaging in assessing degenerative foraminal narrowing in the cervical spine. Contiguous 1.5-mm axial 3DFT gradient-recalled acquisition in the steady state MR images of 120 neural foramina at 60 disk levels were evaluated blindly and independently by three neuroradiologists. High-resolution axial CT was used as the gold standard in all patients. 3DFT MR was found to agree with CT in the detection of neural foraminal narrowing and in the determination of the cause of the narrowing in approximately 76% of neural foramina. The accuracy for the assessment of neural foraminal narrowing on 3DFT MR ranged from 73% to 82% when a 5 degrees-flip-angle, high-intensity CSF technique was used. When using the 30 degrees-flip-angle, low-intensity CSF technique, the accuracy ranged from 66% to 86%. When the cause of narrowing was evaluated, the 5 degrees and 30 degrees studies agreed with CT in 70-92% and 48-88% of the levels, respectively. When lesions were missed on MR, it was usually because of osteophytic disease. The interobserver concordance of MR and CT interpretations was higher for detecting the presence of narrowing than its cause. This MR technique is a useful method in the evaluation of foraminal stenosis since contrast between disk, cord, osteophyte, and CSF is high without the need for intrathecal injections.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
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Paradoxically decreased signal intensity on postcontrast short-TR MR images.

Seven lesions are presented in which short TR/short TE images obtained immediately after IV administration of gadopentetate dimeglumine demonstrated an apparent decrease in signal intensity compared with precontrast short TR/short TE images. All seven lesions were hyperintense on precontrast short TR/short TE images. In four cases in which long TR/long TE scans were also obtained, the lesions were hypointense. This phenomenon may be due to a dominant T2 shortening effect by the contrast material that "overwhelms" T1 shortening even on short TR/short TE scans. Other compounding factors may include variations in scanning variables, receive and transmit attenuations, or a photographic phenomenon due to window widths and center levels.

Contrast Media↗
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Hyperintense thrombus on GRASS MR images: potential pitfall in flow evaluation.

Gradient-recalled acquisition in the steady state (GRASS) MR images, obtained in four patients with angiographic evidence of successful occlusion of cerebral arteriovenous malformations, demonstrated hyperintense signal intraluminally. Although this was initially mistaken as evidence of persistent blood flow in the arteriovenous malformation, the short TR/TE spin-echo images showed hyperintense signal rather than flow void, thereby indicating the presence of subacute thrombus. GRASS images alone should not be used to determine the success of embolotherapy of cerebral arteriovenous malformations or to determine aneurysm patency, since the hyperintense signal is a potential pitfall that may mislead the radiologist in the absence of corroborative images, particularly the short TR/TE spin-echo sequences.

Adolescent↗
PubMedDate not supplied

Pseudoatrophy of the cervical portion of the spinal cord on MR images: a manifestation of the truncation artifact?

Routine evaluation of axial MR images of the cervical spine with high-intensity CSF (long TR/TE spin-echo or gradient-echo images) revealed apparent narrowing of the cord's anteroposterior diameter when these images were compared with corresponding postmyelography CT scans. This discrepancy was believed to be due to the truncation artifact at the CSF-cord boundary. To examine the truncation effect, we compared cord diameters in 12 patients on postmyelography CT scans and MR images and then compared these with MR scans of normal volunteers and of an agar-saline spine phantom. There was an artifactual diminution of the cord diameter in the 128-step phase-encoding axis of the 128 x 256-matrix MR scan as compared with the diameter of the cord in the patients' postiohexol CT scans and in the 256 phase-encoded axis MR scan in the volunteer study. A similar discrepancy was noted in the spine phantom study, in which the cord diameter in the 256-step phase-encoded MR scan, the CT scan, and direct measurement exceeded that in the 128-step phase-encoded axis MR scan. The range of differences between the measurements was as large as 2.3 mm (patients), 1.7 mm (volunteers), and 1.8 mm (phantom) for the three studies. In all three studies, varying the photographic window width and level produced variation in the apparent cord diameter of up to 1.5 mm. To eliminate this effect, the cord diameters in the phantom and the normal control subjects were measured at identical window levels. The truncation artifact, coupled with standard window settings used in photography, may lead to inaccurate display of the diameter of the cervical spinal cord.

Humans↗
PubMedDate not supplied

Comparison of MR imaging with clinical history in the identification of hemorrhage in patients with cerebral arteriovenous malformations.

Twenty-nine patients with true arteriovenous malformations as diagnosed by MR imaging or angiography were examined by MR to detect the presence of hemosiderin deposition, a marker for remote hemorrhage. The resulting information was compared with the clinical record to determine the frequency with which MR demonstrated prior hemorrhagic episodes where no clinical evidence for such episodes existed. Twenty (69%) of 29 patients with arteriovenous malformations showed evidence of acute or older hemorrhage. In four (14%) of 29 cases MR showed a hypointense signal on long TR images, suggesting hemosiderin, but no clinical history could account for prior hemorrhage. Additionally, six (21%) of 29 patients had a clinical history suggestive of acute hemorrhage, but no evidence of bleeding was found on MR. The presence of prior or current hemorrhage is critical to deciding whether to surgically resect the arteriovenous malformation or to treat it conservatively, because of the high rate of rebleeding in patients presenting with hemorrhage or those with a history of this disorder. For this reason, MR imaging has an important role in the management of patients with arteriovenous malformations.

Adolescent↗
PubMedDate not supplied

MR imaging of Tolosa-Hunt syndrome.

The Tolosa-Hunt syndrome consists of painful ophthalmoplegia caused by cavernous sinus inflammation, which is responsive to steroid therapy. The MR features of 11 patients with the clinical diagnosis of Tolosa-Hunt syndrome were studied. Two patients had normal MR studies of the orbit and cavernous sinuses. In nine patients, abnormal signal and/or mass lesions were seen in the cavernous sinuses; in eight cases, the abnormality was hypointense relative to fat and isointense with muscle on short TR/TE images and isointense with fat on long TR/TE scans. Extension into the orbital apex was seen in eight cases. In six of nine cases the affected cavernous sinus was enlarged; in five of nine it had a convex outer margin. One patient had a thrombosed cavernous sinus and superior ophthalmic vein in addition to a cavernous sinus soft-tissue mass. The signal intensity of Tolosa-Hunt syndrome in this limited series was similar to that of orbital pseudotumor and is confined to a limited differential diagnosis, which includes meningioma, lymphoma, and sarcoidosis.

Adolescent↗
PubMedDate not supplied

Olfactory neuroblastoma: MR evaluation.

PURPOSE: To evaluate MR in the diagnosis and staging of olfactory neuroblastoma. METHODS: Five patients with histologically proved olfactory neuroblastomas were studied by MR. Four also had CT scans. RESULTS: The extent of disease delineated by MR agreed with surgical findings and surgical staging of the tumor in all five patients. All cases of olfactory neuroblastomas originated in the nasal cavity and involved the ethmoid sinuses. In three of the five cases, the tumors extended to the anterior skull base. In one case MR correctly suggested skull base involvement missed on CT. Lesions were isointense to hyperintense with muscle on T1-weighted scans. Compared with fat on T2-weighted scans, olfactory neuroblastomas were variable in signal intensity. Enhancement was minimal to moderate in all cases. CONCLUSION: In the evaluation of olfactory neuroblastoma, MR is most useful in delineating the extent of the tumor and may be more accurate than CT. However, the signal intensity characteristics of olfactory neuroblastomas may overlap other tumors.

Adolescent↗
PubMedDate not supplied

MR of intraparotid masses.

PURPOSE: To determine which MR techniques are best for identifying intraparotid masses and to assess the utility of MR for predicting specific diagnosis. METHODS: A retrospective review of 31 intraparotid masses was performed. Lesion conspicuity and signal intensity characteristics were evaluated by objectively measured regions of interest and by subjective visual review. RESULTS: The T1-weighted images produced the highest lesion conspicuity in 25 of 31 masses. All the masses were easily detected as hypointense lesions on the T1-weighted scans with good or excellent conspicuity; on the T2-weighted images nine lesions appeared isointense to the normal parotid tissue, including six malignancies. Gadolinium-enhanced images were not helpful for identifying the intraparotid masses. Warthin tumors and malignancies tended to be hypointense or low in conspicuity on T2-weighted images. CONCLUSIONS: The T1-weighted images were best for detecting parotid masses. The T2-weighted images may help in limiting a differential diagnosis, but a specific diagnosis cannot be made without biopsy.

Contrast Media↗
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Kallmann syndrome: MR evaluation of olfactory system.

PURPOSE: To describe the MR appearance of the olfactory bulbs and tracts and temporal lobes in patients with Kallmann syndrome, a disorder characterized by hypogonadotropic hypogonadism and anosmia. METHODS: High-resolution MR scans with a surface coil placed over the nasion were performed in two patients with Kallmann syndrome. Coronal 3-mm thick contiguous sections were obtained through the olfactory bulbs and tracts. MR scans included volumetric analysis of the bulbs, tracts, temporal lobes, and hippocampi. RESULTS: No olfactory bulbs or tracts could be identified in patients with Kallmann syndrome. In comparison, the olfactory bulbs and tracts were identifiable in seven healthy volunteers. The temporal lobe and hippocampal volumes were comparable between control subjects and Kallmann patients. CONCLUSIONS: High-resolution surface-coil MR can identify the absence of olfactory bulbs and tracts in patients with Kallmann syndrome. Normal olfactory bulbs and tracts are easily discerned with surface-coil imaging.

Adult↗