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Biomedical subjects

W Mayo-Smith

Publications and source records attributed to W Mayo-Smith.

18 recordsLinked to original sources
PubMed1999

MR imaging of the liver with Gd-BOPTA: quantitative analysis of T1-weighted images at two different doses.

This study evaluates the efficacy of gadobentate-dimeglumine (Gd-BOPTA) for enhancement of liver signal-to-noise ratio (SNR) and lesion-liver contrast-to-noise ratio (CNR) on T1-weighted spin-echo (SE) and gradient-recalled-echo (GRE) images at two different doses. Fifty patients with known or suspected liver lesions were examined at 1.5 T. T1-weighted SE (TR/TE 300/12 msec) and GRE images (TR/TE80/4.2 msec/flip angle 80 degrees) were obtained before and at 40-80 minutes and 90-120 minutes after administration of 0.05 or 0.1 mmol/kg Gd-BOPTA. Quantitative measurements of tissue signal intensity were performed at each dose. Liver showed significant enhancement after Gd-BOPTA on T1-weighted SE and GRE images (0.05 mmol: P < 0.05; 0.1 mmol: P < 0.001). The dose of 0.1 mmol/kg provided higher liver SNR than 0.05 mmol/kg. Mean liver SNR was higher on GRE than SE images (P < 0.0001). Lesion-liver CNR significantly increased on GRE images after 0.1 mmol (P < 0.05). There was a trend toward superiority of 0.1 mmol over 0.05 mmol/kg. GRE images were superior to SE images for pre- and post Gd-BOPTA lesion-liver CNR (P < 0.05). Our study suggests that Gd-BOPTA provides prolonged enhancement of liver SNR and CNR, that a dose of 0.1 mmol/Kg appears to be superior than 0.05 mmol/Kg, and that GRE techniques should be used in preference over SE techniques.

Adult↗
PubMed1995

Blood-pool MR contrast material for detection and characterization of focal hepatic lesions: initial clinical experience with ultrasmall superparamagnetic iron oxide (AMI-227).

OBJECTIVE: AMI-227 is an ultrasmall superparamagnetic iron oxide colloid known to enhance tissue T1 and T2 relaxation rates. Animal studies show that AMI-227 has an estimated blood half-life of more than 200 min. In this study, we evaluated the clinical utility of AMI-227 as an MR contrast agent for detection and characterization of focal hepatic lesions, with MR imaging done while the contrast agent is in the intravascular space (blood-pool phase). SUBJECTS AND METHODS: Twenty-two patients with known or suspected focal hepatic masses underwent T1- and T2-weighted MR imaging of the liver at 1.5 T before and immediately after drip infusion of AMI-227 at doses of 0.8, 1.1, or 1.7 mg Fe/kg. Unenhanced and contrast-enhanced images were analyzed qualitatively (lesion detection and tissue characterization) and quantitatively (lesion-liver contrast-to-noise ratio). RESULTS: AMI-227 enhanced signal in normal liver and blood vessels on T1-weighted images and decreased signal in these tissues on T2-weighted images. Qualitatively and quantitatively, lesion-liver contrast was increased for solid tumors (non-cyst and nonhemangioma) at all three doses (p < .02) on both T1- and T2-weighted images. Differentiation between blood vessels and small lesions was easier on contrast-enhanced images, which allowed increased confidence in excluding lesions. Unique enhancement patterns were noted for hemangiomas, solid tumors, and cysts. CONCLUSION: Initial clinical experience suggests that AMI-227 is a useful contrast agent for detection and characterization of focal hepatic lesions.

Adult↗
PubMed1993

Efficacy of sonographically guided biopsy of thyroid masses and cervical lymph nodes.

OBJECTIVE: We performed a prospective study in 96 patients to determine accuracy of sonographically guided fine-needle aspiration biopsy of thyroid masses and cervical lymph nodes. MATERIALS AND METHODS: Real-time sonography was used to guide biopsy of 112 cervical masses in 96 patients (71 patients with impalpable masses, 16 with failed unguided attempts, patient's or physician's preference in nine). The diameters of all masses were less than 3 cm, with a mean of 1.5 cm and a median of 1.5 cm. Twenty-nine masses measured 1 cm or less in diameter, 60 masses between 1.1 and 2.0 cm, and 23 masses between 2.1 and 3.0 cm. Cervical masses that were sampled by biopsy included 75 thyroid masses and 37 lymph nodes. RESULTS: Diagnostic specimens were obtained in 102 (91%) of 112 masses sampled. Sixty-eight (91%) of 75 biopsies of thyroid tissue and 34 (92%) of 37 biopsies of lymph nodes were diagnostic. Nondiagnostic thyroid biopsies included four of complex cysts and three of solid nodules. Sonographic follow-up (1 year) revealed no change or decrease in size of those seven lesions. Sixty of 68 diagnostic thyroid biopsies showed benign processes: 42 macrofollicular adenomas, six colloid adenomas, five microfollicular adenomas, four probable cases of thyroiditis, and three hemorrhagic cysts. The remaining eight diagnostic thyroid biopsies showed malignant processes: seven papillary carcinomas and one metastatic small-cell carcinoma. Of 34 diagnostic biopsies of lymph nodes, 26 showed malignant processes and eight showed benign processes. Surgery in the three patients with nondiagnostic biopsies of lymph nodes revealed two recurrent medullary cancers and one benign node. CONCLUSION: Sonographically guided fine-needle aspiration biopsy of neck masses has a high sensitivity (91%) and should be routinely used to evaluate indeterminate masses in the neck.

Adult↗
PubMed1991

Radiographic appearance of osteopenia.

The radiographic appearance of bone is the result of two physiologic processes: the resorption of bone and the remodeling of bone in response to the stresses applied to it. The relative rates of these two processes will determine the structural and, therefore, the radiographic appearance of the affected bone.

Adult↗
PubMed1990

Subtalar arthralgia caused by juxtaarticular osteoid osteoma.

Juxtaarticular osteoid osteomas in the ankle are frequently misdiagnosed because their symptoms mimic arthritis and may precede roentgenographic findings. In addition, these tumors are rare compared to arthritis and other sources of ankle pain. Four cases of osteoid osteoma of the talus or calcaneus are reported, indicating some of the problems encountered with their identification, and suggestions are made for appropriate investigations to aid in the early and correct diagnosis. The use of plain tomograms, thin-section computed tomograms, and radionuclide scans aid an early and correct diagnosis. Arthroscopy and arthrotomy are often inappropriate.

Adult↗
PubMed1990

Chondroblastoma of the rib. A case report and review of the literature.

Chondroblastoma, a rare bone tumor usually found in the epiphyseal region of long bones, appeared in the rib of a 49-year-old man. Review of the literature reveals that the most common locations for this tumor are the knee and proximal humerus. The most common age group is the second decade. Eighteen cases of chondroblastoma of the rib have been reported in the literature; the patients were older than typical patients with epiphyseal chondroblastoma and had an excellent prognosis after resection of the tumor.

Bone Neoplasms↗
PubMed1989

Age and bone mass in premenopausal women.

It is important to determine the bone mass in normal premenopausal women because increasing numbers of conditions have been identified that result in premenopausal osteoporosis. The relationship between age and bone density was evaluated in 57 carefully characterized normal, premenopausal women using both single energy quantitative computed tomography (SEQCT) and dual energy (DEQCT). The mean bone density measurements were 172 mg/ml K2HPO4 SEQCT and 185 DEQCT. Bone density showed no statistically significant decline between age 18 and age 44. Single- and dual-energy data were highly correlated with each other (r = 0.89), and dual energy appeared to confer no advantage. There was an inverse relation between density and age of menarche. Bone density did not correlate with ideal body weight, percentage fat, or subcutaneous fat area.

Adolescent↗
PubMed1989

Bone and bone marrow changes in Gaucher disease: evaluation with quantitative CT.

The trabecular bone density and bone marrow fat content in eight patients with type 1 Gaucher disease were measured with the use of a modification of dual-energy computed tomography (CT). The results were compared with those in published reports of single-energy quantitative CT measurements in healthy subjects and with dual-energy data obtained in studies of healthy premenopausal women and elderly osteopenic women. The trabecular bone mass was moderately decreased in patients with Gaucher disease. The bone marrow fat content was markedly diminished, presumably due to replacement of marrow fat by Gaucher cells. In healthy and osteopenic subjects single-energy quantitative CT values were lowered by the presence of marrow fat. Comparable single-energy measurements in patients with Gaucher disease reflect greater degrees of bone loss. Low levels of marrow fat may prove to be a valuable marker of the severity of marrow disease.

Absorptiometry, Photon↗
PubMed1989

Body fat distribution measured with CT: correlations in healthy subjects, patients with anorexia nervosa, and patients with Cushing syndrome.

Computed tomography (CT) was used to study fat distribution in three groups of women of comparable age: 39 healthy volunteers, 15 patients with anorexia nervosa, and seven with Cushing syndrome. Patients with anorexia nervosa had a fivefold decrease in subcutaneous fat and only a twofold decrease in intraabdominal fat compared with the values for the volunteers. Patients with Cushing syndrome had less than a twofold increase in subcutaneous fat and greater than a fivefold increase in intraabdominal fat compared with values for the healthy subjects. These findings suggest that fat in different body compartments responds differently to disease processes and that CT can be used to measure these changes.

Adipose Tissue↗
PubMed1989

Intravertebral fat measurement with quantitative CT in patients with Cushing disease and anorexia nervosa.

Dual-energy quantitative computed tomography can be used to calculate the intravertebral fat content as well as to correct the effect of intravertebral fat on bone density measurements. The authors studied seven female patients with Cushing syndrome and 15 female patients with anorexia nervosa--conditions known to result in abnormalities of somatic fat distribution--to determine whether the intravertebral fat content was normal and whether it reflected somatic fat quantities. Intravertebral fat content could not be predicted on the basis of somatic fat, weight, or bone mineral content. Intravertebral fat content was elevated in patients with anorexia nervosa (compared with normal values in young female volunteers). In patients with anorexia, the amount of fat increase was disproportionately large for the severity of osteopenia. In patients with Cushing syndrome, the intravertebral fat content did not differ from that in the volunteers. Intravertebral fat does not correlate well with bone mineral content within any group and appears to be related to other factors.

Adolescent↗
PubMed1988

Galeazzi injury with an associated fracture of the radial head.

A 36-year-old man sustained an injury that was a combination of Essex-Lopresti and Galeazzi fractures. His injuries consisted of a distal radial shaft fracture, a radial head fracture, and disruption of the distal radioulnar joint. These injuries are uncommon and this combination seems not to have been reported. The mechanism of the causative forces and the position of the forearm on impact is different in each of these injuries. These differences may explain the rarity of the combination.

Adult↗
PubMed1981

Wheelchair cushion modification: device for locating high-pressure regions.

Location and geometry of bony prominences must be known in order to modify foam wheelchair cushions to reduce high seating pressures beneath patients susceptible to decubitus ulcers. A portable, adjustable "wheelchair barograph" has been built that will identify high pressure regions clinically by means of light patterns. No electronic readout is required to obtain accurate records of high pressure regions on the seating surface which may be added to the patient's record or used directly to mark locations for cushion modification.

Buttocks↗
PubMedDate not supplied

Comparison of in-phase and out-of-phase gradient recalled echo T1-weighted pulse sequence for MR imaging of malignant liver masses following administration of paramagnetic gadolinium-chelate.

BACKGROUND: The purpose of this study was to compare the performance of in-phase and out-of-phase gradient recalled echo (GRE) pulse sequences on paramagnetic contrast-enhanced magnetic resonance (MR) imaging of malignant liver lesions. METHODS: Fifty patients (27 women, 23 men; mean age = 50 +/- 27 years) with known or suspected focal liver lesions, nine of whom had a fatty liver, were examined at 1.5 T before and 60 min after injection of gadobenate dimeglumine at a dose of 0.05 or 0.1 mmol/kg using two GRE techniques: echo time of 2.3 ms (out-of-phase) or 4.6 ms (in-phase). Liver signal-to-noise ratio (SNR) and lesion-liver contrast-to-noise ratio (CNR) were calculated. RESULTS: In patients with a nonfatty liver, liver SNR increased from 26 +/- 9 to 41 +/- 17 on in-phase images and from 28 +/- 8 to 45 +/- 14 on out-of-phase images. In patients with a fatty liver, in-phase images provided significantly higher (p < 0.01) liver SNR than did out-of-phase images predose (34 +/- 8 on in-phase vs. 21 +/- 8 on out-of-phase) and postdose (44 +/- 13 on in-phase vs. 33 +/- 14 on out-of-phase). In patients with a nonfatty liver, lesion-liver CNR was similar on in-phase and out-of-phase images, predose and postdose. In patients with fatty liver, lesion-liver CNR was significantly (p < 0.01) lower on out-of-phase images on predose and postdose images. CONCLUSION: In-phase GRE imaging is recommended for imaging focal liver lesions on paramagnetic contrast-enhanced MR imaging in patients with fatty infiltration of the liver.

Adult↗
PubMedDate not supplied

Fatty replacement of spinal bone marrow due to radiation: demonstration by dual energy quantitative CT and MR imaging.

Dual energy CT and quantitative magnetic resonance (MR) imaging were used to evaluate marrow changes due to radiation. The bright signal intensity seen on MR was shown by the two quantitative techniques to be due to a threefold increase in the marrow fat content compared with nonradiated levels and to a normal control. Fat estimates by MR and dual energy CT were in excellent agreement. Single energy CT overestimates the amount of bone loss in the radiation field. Dual energy CT and quantitative MR can be used to correct this error.

Adipose Tissue↗
PubMedDate not supplied

Cytologic diagnosis of pancreatic cystic lesions. A prospective study of 28 percutaneous aspirates.

PURPOSE: To prospectively evaluate fine needle aspiration biopsy (FNAB) of pancreatic cystic lesions. STUDY DESIGN: We performed a blind, prospective study on percutaneous aspirates from 28 radiographically identified cysts, including 6 inflammatory cysts (5 pseudocysts and 1 abscess), 4 serous cystadenomas, 1 cystic islet cell tumor, 5 mucinous cystic neoplasms, 6 mucinous cystadenocarcinomas and 6 nonpancreatic cysts. RESULTS: Four of six (67%) cystadenocarcinomas were identified as malignant, and the other two, which lacked sufficient morphologic criteria for malignancy, as consistent with mucinous cystic neoplasm. Two of five mucinous cystic neoplasms were correctly classified. One, which contained atypical cells, did not appear to be mucinous on the ThinPrep, and one, which lacked an epithelial component, was suggested because of the presence of mucin in the background. The fifth one contained inflammatory cells only. One of four serous cystadenomas produced a diagnostic specimen. FNAB of the cystic islet cell tumor was nondiagnostic. Five of six inflammatory cysts (83%) were correctly diagnosed, whereas one case produced an acellular, nondiagnostic specimen. Six of 28 (23%) cases were nonpancreatic cysts, aspirated under the presumption that they were pancreatic cysts based on radiologic studies: only one case, a papillary cystadenocarcinoma of the stomach, was correctly diagnosed; the other five cases were nondiagnostic, and in two of these the assumption that the cysts were pancreatic in origin precluded an accurate classification. CONCLUSION: FNAB of pancreatic cystic lesions can differentiate mucinous from nonmucinous pancreatic cysts and provide definitive evidence of malignancy. In some cases, serous cystadenomas can be diagnosed. Pseudocysts can be suspected on the basis of an inflammatory smear lacking both epithelial cells and background mucin, but this finding is not specific. Nonpancreatic lesions constitute a significant percentage of cases aspirated as pancreatic cysts and present a major pitfall in cytologic interpretation.

Biopsy, Needle↗