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Biomedical subjects

E H Dillon

Publications and source records attributed to E H Dillon.

At least 19 recordsLinked to original sources
PubMed1994

MR diagnosis of paraganglioma of the head and neck: value of contrast enhancement.

OBJECTIVE: Contrast enhancement with gadopentetate dimeglumine has been advocated to increase the efficacy of MR imaging for paragangliomas of the head and neck. However, contrast media are expensive, time-consuming to use, and involve minimal but not negligible risks. The purpose of this study was to determine if the use of contrast material is warranted in patients undergoing MR imaging for the diagnosis of paragangliomas of the head and neck. MATERIALS AND METHODS: Unenhanced MR images were compared with images obtained after administration of gadopentetate dimeglumine in 23 healthy subjects and 37 patients who had a total of 71 tumors. Three combinations of sequences were reviewed independently and in a random order by four observers who had no clinical information. Combination A comprised enhanced and unenhanced T1-weighted sequences, combination B comprised unenhanced T1- and T2-weighted sequences, and combination C was a combination of all sequences. A four-point scale of certainty was used. CT, scintigraphic, angiographic, and surgicopathologic findings were used as the standard of reference. Results were subjected to alternative free-response receiver-operating-characteristic (AFROC) scoring and statistical analysis. RESULTS: The mean areas under the AFROC curve for combinations A, B, and C were 0.761, 0.856, and 0.827, respectively. Mean sensitivity/specificity values after dichotomizing the scoring results were 0.73/0.94, 0.79/0.95, and 0.78/0.94 for combinations A, B, and C, respectively. The performance of combinations B and C did not differ markedly, but both combinations were significantly better than combination A. In a relatively large percentage (36%) of small postoperative tumor residues not detected on unenhanced images, however, gadopentetate dimeglumine allowed detection. CONCLUSION: The results of this study indicate that, in general, the use of gadopentetate dimeglumine is not necessary for the detection of head and neck paragangliomas. The addition of contrast-enhanced imaging does not increase the sensitivity or specificity compared with imaging without enhancement. Only when searching for small postoperative tumor residues is the addition of gadopentetate dimeglumine warranted.

Adult↗
PubMed1994

Variations in venous and segmental anatomy of the liver: two- and three-dimensional MR imaging in healthy volunteers.

OBJECTIVE: The purpose of this study was to use two- and three-dimensional analysis of thin-slice MR imaging data to study the anatomic variations in the segmental anatomy of the liver. It is important to recognize these anatomic variations in order to ensure accurate localization of hepatic lesions and preoperative delineation of resection planes. SUBJECTS AND METHODS: T1-weighted MR images of contiguous 4-mm sections were obtained in 10 healthy subjects. We measured the orientations of external and internal hepatic landmarks that indicated segmental boundaries and created three-dimensional renderings of hepatic veins, intrahepatic portal branches, liver surface, and gallbladder. RESULTS: Variations in the portal branching pattern were seen in eight of 10 subjects. Most variations occurred in the right hemiliver and consisted of the absence of a right portal trunk or the presence of accessory portal branches. The division between right anterior and right posterior segments was inclined posteriorly (average, 31.2 degrees) relative to the right hepatic vein. The landmarks indicating the position of the umbilical fissure showed marked variability. Only two of 10 subjects had three hepatic veins, with the left and middle veins sharing a common trunk. In the remaining eight subjects, nine accessory veins were present: three left, one middle, and five right. CONCLUSION: Planes of resection in liver surgery are largely determined by the precise position of tumor relative to the individual segmental anatomy. Consequently, localization of liver lesions and preoperative delineation of resection planes requires consideration of the significant anatomic variations in the segmental anatomy of the liver. These anatomic variations can be depicted on two- and three-dimensional displays of T1-weighted MR images of contiguous 4-mm sections.

Adult↗
PubMed1994

Portal venous and segmental anatomy of the right hemiliver: observations based on three-dimensional spiral CT renderings.

OBJECTIVE: The purpose of this study was to evaluate the segmental anatomy of the right hemiliver and to assess whether the right hepatic vein and right portal trunk are accurate indicators of the position of the right and transverse scissurae, respectively. SUBJECTS AND METHODS: We examined 26 patients with spiral CT using 5-mm slices, reconstructed at 2-mm intervals. Three-dimensional renderings of the portal and hepatic venous structures were created. The portal ramification pattern and relationship between the hepatic veins and portal system were evaluated. RESULTS: In the right hemiliver, an anterosuperior sector and a posteroinferior sector were present in all patients. In addition, in nine patients, a total of 15 accessory portal sectors were present, each arising directly from the portal bifurcation or the right portal trunk. Further subdivision of the portal sectors showed marked individual variability, with no prevailing branching pattern. The scissura between the anterosuperior and posteroinferior sectors showed an angled orientation--its cranial part was tilted posteriorly (average, 58.4 degrees) and its caudal part was tilted anteriorly (average, 2.8 degrees)--relative to the coronal plane. In 24 patients, portal branches crossed the plane of the right hepatic vein. No transverse scissura could be seen in the anterosuperior or posteroinferior sector. CONCLUSION: The right hemiliver could be divided into anterosuperior and posteroinferior sectors in all patients studied. Many patients have accessory sectors. Further subdivision into portal segments can be described only after the individual portal branching pattern has been studied. The right hepatic vein is an inaccurate indicator of the position of the right scissura. No clear transverse scissura can be seen in the right hemiliver.

Adult↗
PubMed1994

A method for sonographic counting of the lower vertebral bodies in newborns and infants.

PURPOSE: To determine whether the lumbosacral junction of the vertebral column can be identified with sonography in newborns and infants and thus serve as a method for counting the lumbar and sacral vertebral bodies. METHODS: In 32 newborns and infants, the number of ossified vertebral bodies distal to the lumbosacral junction was counted with sonography and radiography. RESULTS: Sonographic and radiographic findings agreed in 29 of 32 examinations (91%). CONCLUSIONS: The lordotic transition at the lumbosacral junction can be identified with sonography in the majority of newborns and infants, allowing intraspinal structures to be related to a specific vertebral level.

Female↗
PubMed1993

MRI of the pulmonary artery after arterial switch operation for transposition of the great arteries.

Twenty-six children who underwent an arterial switch operation for transposition of the great arteries were examined with MRI and Doppler ultrasound (US). The aim was to determine the capability of MRI for detecting a possible stenosis of the pulmonary arteries. In 10 children angiocardiography (ACG) was done after the MRI examination. Using ACG as the gold standard, MRI was sensitive in the detection of pulmonary artery stenosis. MRI was more precise in the localization of a stenosis than was Doppler US. Right ventricular hypertrophy was a sensitive indicator of pulmonary artery stenosis. These results suggest that MRI could serve as a screening examination for pulmonary artery stenosis after an arterial switch operation.

Adolescent↗
PubMed1993

Endovaginal pulsed and color Doppler in first-trimester pregnancy.

Endovaginal pulsed and color Doppler techniques were used to evaluate 23 unselected first-trimester pregnancies prior to elective abortion. Mean estimated gestational age was 8.9 +/- 1.6 weeks (range = 6.6-13.0). Low impedance, high velocity peritrophoblastic flow was seen in all cases. Mean peak systolic and end-diastolic velocities were 41.0 +/- 19.7 and 22.9 +/- 6.5 cm/s; mean resistance index (RI) was 0.41 +/- 0.10. Forty-five uterine arteries were evaluated with mean peak systolic and end-diastolic velocities of 44.1 +/- 14.7 and 7.6 +/- 4.3 cm/s; mean RI was 0.81 +/- 0.10. The peritrophoblastic and uterine artery velocities did not correlate with gestational age. Both ovaries were evaluated in 14 patients. One had no detectable flow in either ovary. For the active ovary in the other 13 patients, mean peak systolic and end-diastolic velocities were 27.4 +/- 9.9 and 15.2 +/- 5.9 cm/s; mean RI was 0.44 +/- 0.09. The corresponding values for the inactive ovary were 8.9 +/- 3.8 cm/s, 2.0 +/- 2.0 cm/s, and 0.76 +/- 0.22. These results can be used as a baseline for future studies of abnormal pregnancies.

Adult↗
PubMed1993

Carotid bifurcation imaging: magnetic resonance angiography compared to conventional angiography and Doppler ultrasound.

PURPOSE: to evaluate the clinical usefulness of the two dimensional "Time of Flight" (2D TOF) Magnetic Resonance Angiography technique (MRA) in imaging the carotid bifurcation as compared to conventional angiography and pulsed and colour Doppler ultrasound. METHODS: in 19 patients with possible cerebrovascular disease and eight volunteers, contrast angiography was compared with MRA in 21 carotid bifurcations and with Doppler ultrasound in 23 bifurcations by two independent observers. In 19 bifurcations, all three techniques were available for comparison. Internal carotid arteries were graded normal/minimal disease, mild, moderate or severe stenosis, or occluded. RESULTS: overall agreement between contrast angiography and MRA existed in 62% for one observer and 76% for the other. When MRA and Doppler agreed, agreement between these two investigations and contrast angiography existed in 77-81%. The major problem with MRA was overestimation of moderately stenosed vessels; 50% of the vessels with a moderate stenosis on contrast angiography were judged severely stenosed on MRA. An occlusion was never mistaken for a stenosis by MRA. Evaluating the separate slices, acquired in the 2D TOF MRA investigation, appeared to be essential to avoid this mistake. CONCLUSION: at present 2D TOF MRA is not clinically useful for diagnosing the degree of carotid artery stenosis. MRA has a clear tendency to overestimate the degree of stenosis especially moderately severe stenoses. To date, there are no objective methods to correct for this mistake. Technical improvements may make MRA a better diagnostic tool in the future.

Adolescent↗
PubMed1993

Endovaginal US and Doppler findings after first-trimester abortion.

Endovaginal ultrasound (US) imaging and color Doppler flow imaging techniques were used to evaluate the uterus and its contents and to establish characteristics of a normal post-abortion appearance in 19 women who underwent elective first-trimester abortions. Twenty-two examinations were performed between 2 and 17 days after the procedure. Thirteen of the 22 examinations (59%) showed different amounts of intrauterine material of varying echogenicity. Seven of the 22 examinations (32%) showed a thick endometrial stripe, and only two showed a normal stripe. Color Doppler flow imaging demonstrated typical peritrophoblastic flow in four of eight patients on the second and third days after the abortions were performed. After the third day, flow was observed in only two of 11 patients, and intrauterine material was also seen. These results indicate that intrauterine material and low-impedance flow are frequently observed after an abortion and do not necessarily indicate clinically important retained products of conception.

Abortion, Induced↗
PubMed1993

CT angiography: application to the evaluation of carotid artery stenosis.

PURPOSE: To determine whether computed tomographic (CT) angiography can be used to accurately quantify carotid stenoses and differentiate severe stenoses from occlusions. MATERIALS AND METHODS: CT angiography was used to evaluate 50 carotid arteries in 27 patients who were referred for surgical evaluation after diagnosis of carotid stenosis and who had undergone standard angiography. Four observers read each study separately in a blinded fashion, then all four observers together reviewed those studies in which the individual readings differed to reach a consensus reading. RESULTS: The consensus readings for the two modalities were in agreement on stenosis category in 41 (82%) of the 50 carotid arteries (kappa W = 0.852 +/- 0.114). The consensus readings in the other nine arteries differed by only one category; seven had less severe stenosis at CT angiography and two had more severe stenosis. The CT angiograms also depicted a variety of additional abnormalities, including loops (n = 6), aneurysms (n = 2), and ulcers (n = 4). CONCLUSION: These results indicate that CT angiography can non-invasively provide most of the information needed before carotid endarterectomy.

Adult↗
PubMed1993

Partial anomalous pulmonary venous drainage of the left upper lobe vs duplication of the superior vena cava: distinction based on CT findings.

OBJECTIVE: Partial anomalous pulmonary venous drainage of the left upper lobe and duplication of the superior vena cava have similar appearances on CT scans. The purpose of this study was to review their appearances and provide guidelines for differentiating between them. MATERIALS AND METHODS: A review of the CT reports for the preceding 4 years disclosed seven patients whose original diagnosis was duplication of the superior vena cava and one patient whose diagnosis was partial anomalous pulmonary venous drainage of the left upper lobe. The 14 CT examinations of these eight patients were reviewed in order to observe the CT findings in each anomaly. RESULTS: In only five of the seven patients whose original diagnosis was duplication of the superior vena cava were CT findings compatible with that diagnosis. In the other two, CT findings were compatible with partial anomalous pulmonary venous drainage of the left upper lobe, as they were in the one patient with that as his original diagnosis. Two CT findings allow consistent differentiation. In duplication of the superior vena cava, two vessels can be seen anterior to the left main bronchus, whereas no vessels are present in this location in partial anomalous pulmonary venous drainage of the left upper lobe. Additionally, careful inspection reveals that the intraparenchymal veins in the left upper lobe drain to the normally positioned left superior pulmonary vein in duplication of the superior vena cava, whereas they drain to the anomalous vessel in partial anomalous pulmonary venous drainage of the left upper lobe. CONCLUSION: Careful analysis of the CT scans with particular attention to these two features allows differentiation between partial anomalous pulmonary venous drainage of the left upper lobe and duplication of the superior vena cava.

Congenital Abnormalities↗
PubMed1993

Spiral CT angiography.

Spiral CT angiography is a new, minimally invasive technique for vascular imaging that is made possible by combining two recently developed techniques: slip-ring CT scanning and computerized three-dimensional (3D) reconstruction. The purpose of this essay is to illustrate the appearances of various normal and diseased vessels using this technique.

Angiography↗
PubMed1991

Follow-up of grade 2 meniscal abnormalities in the stable knee.

A prospective study of grade 2 meniscal abnormalities in patients with intact anterior cruciate ligaments was done to ascertain whether such lesions progress to complete tears. A follow-up magnetic resonance (MR) image was obtained in 22 patients in whom the initial MR image showed a grade 2 lesion in one or both menisci that had been proved at arthroscopy not to be torn. On the initial images, 27 menisci contained a grade 2 lesion. At follow-up, six of the 27 lesions appeared to have decreased in size (two had completely disappeared). Eighteen lesions appeared unchanged; only three had increased in size. The mean interval between the acquisition of initial and follow-up images was 27.3 months (range, 11-41 months). The two patients whose lesion disappeared were among the youngest patients evaluated. The three patients whose abnormality increased were slightly older and more active than average. The results suggest that in most patients grade 2 lesions are stable at up to 3 years follow-up.

Adolescent↗
PubMed1990

The clinical significance of stage 2 meniscal abnormalities on magnetic resonance knee images.

The Stage 2 meniscal abnormality was subdivided into Stage 2A--linear abnormal signal not contacting an articular surface, Stage 2B--abnormal signal in contact with the articular surface on a single image, Stage 2C--extensive wedge-shaped signal abnormality not in contact with an articular surface. Arthroscopy showed tears in 2A 3%, 2B 0%, 2C 50%. Complete tears should only be diagnosed if contact is seen on more than one image. Many Stage 2C menisci may have tears.

Adult↗
PubMed1990

Pseudogestational sacs: Doppler US differentiation from normal or abnormal intrauterine pregnancies.

Doppler ultrasound (US) evaluation of 40 empty intrauterine sac-like structures was performed to evaluate the ability of this technique to permit distinction between intrauterine pregnancy and pseudogestational sac associated with ectopic pregnancy. Proof of the location of the pregnancy was available in all cases. There were 31 intrauterine pregnancies, of which 23 were missed or incomplete abortions and eight were early normal pregnancies. With an insonating frequency of 3 MHz, the average frequency shift detected from these intrauterine pregnancies was 1.7/1.0 kHz (peak systolic/end diastolic ratio). Nine pseudogestational sacs were evaluated, of which seven demonstrated no flow and two demonstrated minimal flow that averaged 0.4/0.1 kHz. Defining intrauterine peritrophoblastic flow as a peak systolic frequency shift of 0.8 kHz or greater (equivalent to 21 cm/sec with an angle of 0 degree) correctly classifies 26 of the 31 intrauterine pregnancies and all of the nine pseudosacs. The sensitivity of the Doppler technique for the detection of intrauterine pregnancies was 84%, and the specificity was 100%.

Abortion, Incomplete↗