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Biomedical subjects

W D Foley

Publications and source records attributed to W D Foley.

At least 55 records · Page 3Linked to original sources
PubMed1987

Contrast optimization for the detection of focal hepatic lesions by MR imaging at 1.5 T.

The relative efficacies of different spin-echo pulse sequences at 1.5 T were evaluated in the detection of focal hepatic disease. Pulse sequences compared were spin-echo with a repetition time (TR) of 200 msec and echo time (TE) of 20 msec, with six excitations; TR = 300 msec, TE = 20 msec, with 16 excitations (T1-weighted sequences); and a double spin-echo with TR = 2500 and TE = 25 and 70, with two excitations (proton-density-weighted and T2-weighted pulse sequences, respectively). Respiratory-motion compensation, which involved a recording of the phase-encoding gradients (Exorcist), was used for the last two sequences. Spin-echo with TR = 2500 msec and TE = 70 msec was superior in lesion detection and contrast-to-noise ratio. The proton-density-weighted and T2-weighted sequences with respiratory compensation produced better artifact suppression than did the short TR, short TE T1-weighted sequence with temporal averaging. In contradistinction to prior results at 0.6 T, T2-weighted pulse sequences appear superior to T1-weighted pulse sequences with multiple excitations for both lesion detection and artifact suppression at 1.5 T.

Cysts↗
PubMed1987

Evaluation of ECG gating for selective intraarterial carotid DSA.

A study comparing ECG-gated and nongated acquisition for selective carotid digital subtraction arteriography was performed on 116 bifurcations in 63 patients. For ECG acquisition, three exposures (systole, early diastole, and late diastole) were obtained for each cardiac cycle. There was no significant difference in the frequency of plaque misregistration between gated (18%) and nongated (23%) acquisitions. In gated studies, the frequency of plaque misregistration was equivalent in systole, early diastole, and late diastole. Gated and nongated studies provided equivalent image quality for selective carotid digital subtraction angiographic studies.

Carotid Arteries↗
PubMed1987

Evaluation of ECG gating and hybrid subtraction for intraarterial digital subtraction thoracic aortography.

A comparative study was made of ECG-gated and nongated intraarterial digital subtraction angiography of the thoracic aorta by using conventional temporal subtraction and combined temporal/energy (hybrid) subtraction. ECG-gated studies were acquired at three frames per cardiac cycle. In 85% of patients, gated conventional subtraction resulted in studies of superior image quality in comparison with those obtained with hybrid techniques, both gated and nongated. In the 15% in whom hybrid subtraction studies were judged superior, the hybrid images were almost exclusively integrated by video frame averaging and thus were nongated. In a separate subset of patients who had conventional nongated studies, there was no difference in the percentage of diagnostic studies (93%) and nondiagnostic studies (7%) when compared with conventional gated temporal subtraction. Cardiac gating appears to be superior to hybrid subtraction for studies of the thoracic aorta that use intraarterial digital subtraction angiography, but neither technique offered any significant advantage over conventional nongated acquisition.

Aged↗
PubMed1986

Digital and conventional chest images: observer performance with Film Digital Radiography System.

The Film Digital Radiography System (FilmDRS) is a device with a laser optical film digitizer, 2,000 X 2,000 X 12-bit memory, and a 1,000-line video display. To evaluate the adequacy of this device for general radiography of the chest, four readers independently analyzed both radiographs and the corresponding video display of the digitized chest images of 150 patients, consisting of 100 images of abnormalities and 50 normal images. The overall results indicate equal sensitivity for the two systems. The FilmDRS, with interactive windowing, proved superior in the detection of hilar and mediastinal disease. X-ray film was superior in allowing detection of hyperlucent states. There was equivalent sensitivity for other disease categories. Superior specificity was achieved with conventional radiographs.

Analog-Digital Conversion↗
PubMed1986

Focal hepatic masses and fatty infiltration detected by enhanced dynamic CT.

A prospective evaluation of 185 consecutive patients with abdominal pain or suspected hepatic malignancy was performed to compare the diagnostic accuracy of contrast material-enhanced incremental dynamic computed tomography (IDCT) scans with plain CT scans for detection of hepatic masses and fatty infiltration of the liver. After a series of nondynamic plain CT scans, patients were examined at 7.5 scans/min during intravenous injection of 50 g of iodinated contrast material. Enhanced IDCT study was found to be an accurate, reproducible technique for liver evaluation. Of 155 neoplasms measured in 59 patients, liver-to-lesion differences of less than 10 HU were seen in only two tumors in IDCT scans as compared with 31 in plain CT scans. These differences were not significantly affected by lesion size for neoplasms greater than 6 mm in diameter. A confident diagnosis of fatty infiltration (23 patients) could be made when the spleen-minus-liver difference was 25 HU on enhanced IDCT scans and 10 HU on plain CT scans. In eight patients with liver metastases, there was little variation in the attenuation values of normal-appearing liver between serial examination studies (8 HU average).

Contrast Media↗
PubMed1986

I.v. and intraarterial hybrid digital subtraction angiography: clinical evaluation.

Temporal/energy (hybrid) subtraction is a technique for removing soft-tissue motion artifact from digital subtraction angiograms. The diagnostic utility of hybrid subtraction for i.v. and intraarterial angiography was assessed in the first 9 months of operation of a dedicated production system. In i.v. carotid arteriography (N = 127), hybrid subtraction (H) provided a double-profile projection of the carotid bifurcation in an additional 14% of studies, compared with temporal subtraction (T) alone (H79:T48, p less than 0.001). However, a change in estimated percent stenosis or additional diagnostic information occurred in only 2% of studies. In i.v. abdominal arteriography (N = 23), hybrid subtraction, compared with temporal subtraction, provided a diagnostic examination in an additional 14% of studies (H20:T17); however, this difference is not statistically significant. An additional three i.v. abdominal angiograms were nondiagnostic. In intraarterial abdominal (N = 98) and pelvic (N = 60) angiography, hybrid subtraction provided a diagnostic examination in an additional 5% of studies (abdomen H94:T90, pelvis H58:T56); this difference was not statistically significant. An additional 5% of all intraarterial abdominal and pelvic digital subtraction angiographic studies were considered nondiagnostic. Hybrid subtraction provides a double-profile view of the carotid bifurcation in a significant number of patients. However, apart from some potential for improved i.v. abdominal arteriography, hybrid subtraction does not result in significant improvement in comparison to conventional temporal-subtraction techniques.

Adolescent↗
PubMed1986

CT of aortic dissections.

Dissecting aortic aneurysms are one of the few medical emergencies where prompt recognition is crucial. Contrast-enhanced computed tomography combined with dynamic scanning offers an excellent noninvasive means to evaluate patients with suspected aortic dissection. At the Medical College of Wisconsin, we retrospectively reviewed all patients who were referred to the Section of Computed Body Tomography with the diagnosis of suspected aortic dissection. Over 100 patients were studied. The sensitivity, specificity, and overall accuracy of computed tomography was greater than 95%.

Adult↗
PubMed1986

The effect of varying high pass filter parameters on the detectability of isolated pulmonary nodules in digitized chest images.

The effect of image processing of digital radiographic data on lesion detectability in clinical images has not been systematically studied. In this experiment, we evaluated a low frequency suppression filter program applied to CT digital radiographic localization images (General Electric Scoutview). Three different filter parameters affecting edge enhancement and local image contrast were applied to a set of digital chest images. A standard observer detection experiment comparing the variously filtered digital images and standard chest radiographs in the detection of lung nodules (11 peripheral lung fields, one superimposed on aortic arch) was performed. Standard chest radiography was more sensitive than the digital chest images, although some improvement was noted with increase in local image contrast and edge enhancement. Both image formats were equally specific. Image processing would be better evaluated using a digital imaging system with better performance parameters.

Analog-Digital Conversion↗
PubMed1985

Computed tomography in the staging of small cell lung cancer: implications for combined modality therapy.

Computed tomography of the thorax and abdomen, from the thoracic inlet to the renal hila, was performed as part of initial staging in 51 patients with small cell carcinoma of the lung (SCCL). The computed tomographic (CT) scans were repeated after completion of chemotherapy, as part of routine restaging and assessment of response to therapy. To identify the ways in which CT scanning uniquely benefited evaluation of initial disease extent in comparison to other diagnostic studies exclusive of CT scan, all diagnostic and clinical data were reviewed. CT scan identified more advanced intrathoracic disease than chest radiography in 82% of patients. Mediastinal node involvement not appreciated by chest radiography was seen in 61% of patients. Adrenal and retroperitoneal node involvement, not suspected by other studies, was identified by CT scan in 31% and 12% of patients, respectively. Thirty percent of the patients staged as limited disease (LD) were advanced to extensive disease (ED) by CT scan findings. While confirmation, by biopsy, of positive CT findings was not consistently accomplished, restaging CT scans provided indirect confirmation by displaying improvement or worsening that correlated with disease regression or progression. Thoraco-abdominal CT scanning more accurately identifies the extent of small cell carcinoma than other imaging procedures. This has important implications for reporting results by extent of disease. In addition, CT more accurately identifies the magnitude of intrathoracic primary and nodal tumors, which may influence the choice and conduct of local treatment--surgery and/or radiation therapy--in combination with systemic chemotherapy.

Carcinoma, Small Cell↗
PubMed1985

Digital subtraction angiography of the extremities using table translation.

Digital subtraction angiography (DSA) of the extremities has been performed with both intravenous and intraarterial injections of contrast material. Intravenous studies are usually site specific and are limited by contrast material load; a complete intraarterial study with multiple injections of contrast material may be time consuming. A feasibility study to evaluate a DSA technique that would allow table translation and imaging of two contiguous regions following a single injection of contrast material--bolus-chase DSA--was performed. Forty-five examinations were performed, 13 intravenously and 32 intraarterially. Twelve intravenous and 16 intraarterial DSA examinations were totally satisfactory. Inadequate studies were predominantly caused by slow arterial clearance of contrast material in the distal calf and by operator error. Compared with conventional DSA, anatomic studies of lower-extremity vessels could be obtained faster and with lower contrast material loads using bolus-chase DSA.

Adult↗
PubMed1985

Evaluation and treatment of intraabdominal bilomas.

In a 3-year period, 21 intraabdominal bilomas developed in 18 patients. Fifteen of the patients had a solitary biloma, and the other three patients each had two separate concurrent bilomas. The major cause of biloma formation was postoperative bile leakage from a bile duct after laparotomy done primarily for surgery on the gallbladder or liver. Maximal diameter of the bilomas in the transaxial plane ranged from 2 to 19 cm. Sixteen of the bilomas were in the right upper quadrant, and five were in the left upper quadrant. Two large right-sided collections extended caudally into the lower abdomen. The contours of the bilomas were configured by the diaphragm, mesenteries, liver, and other abdominal organs. On CT and sonography, the bilomas were invariably well demarcated, but most did not have an identifiable capsule. CT did demonstrate a thin rim on four bilomas and a thick rim on one. In 19 bile collections, the CT numbers were less than 20 H. The combination of the clinical history, the location, and the CT appearance of the lesion led to the correct diagnosis in each case. Percutaneous drainage was an effective form of therapy that often eliminated the need for surgical drainage.

Abdomen↗
PubMed1985

Intra-arterial digital subtraction angiography.

DSA is an imaging technique that should be integrated into a state-of-the-art angiographic system for proper application and utilization. This results in improvements in both efficiency and diagnostic accuracy. However, from the physician's viewpoint, the proper use of a DSA imaging facility mandates not only an understanding of angiographic principles as applied with conventional film-screen systems but also an in-depth understanding of the factors that affect DSA performance. In particular, factors affecting spatial resolution and contrast sensitivity are crucial. This knowledge has to be applied interactively and "on-line" to achieve optimal IA-DSA image quality.

Angiography↗