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S F Quinn

Publications and source records attributed to S F Quinn.

At least 37 records · Page 2Linked to original sources
PubMed1994

Phase unwrapping in the three-point Dixon method for fat suppression MR imaging.

PURPOSE: TO present an algorithm for performing phase unwrapping for fat and water signal separation in the three-point Dixon (3PD) method of magnetic resonance (MR) imaging. MATERIALS AND METHODS: The algorithm is based on a two-dimensional region-growing approach, which tracks phase evolution in 3PD images and unwraps the phase when a 2 pi jump is detected. The unwrapped phase data are consecutively used to calculate fat and water signal components on a per-pixel basis. The method was tested in eight volunteers. RESULTS: The algorithm creates four output images: standard spin-echo, fat suppression, water suppression, and phase map images. This method corrects for the effects of magnetic field inhomogeneities and provides spatially uniform fat signal suppression superior to that achievable with the standard method. CONCLUSION: This method of 3PD data reconstruction appears to be promising for routine application of fat suppression MR imaging in a clinical setting.

Humans↗
PubMed1994

Chondromalacia patellae: fat-suppressed MR imaging.

PURPOSE: To evaluate the accuracy of fat-suppressed magnetic resonance (MR) imaging in diagnosing chondromalacia patellae. MATERIALS AND METHODS: Seventy-one patients underwent fat-suppressed MR imaging and arthroscopy of the patellofemoral compartment. Findings were classified as early or advanced chondromalacia or as normal and were correlated with arthroscopic findings. RESULTS: Early and advanced stages of chondromalacia patellae were reliably detected, with positive predictive values of 85% and 92%, respectively. Specificity in early stages was 94% and in late stages was 98%. However, the overall accuracies did not differ substantially from those reported in studies that did not use fat-suppressed imaging. CONCLUSION: Axial, fat-suppressed MR imaging accurately depicts changes caused by chondromalacia patellae. Early stages can be seen as intrasubstance changes of increased signal intensity. Results of this study suggest a high degree of specificity in excluding both early and advanced changes.

Adolescent↗
PubMed1994

MR imaging of the patellofemoral compartment.

This article reviews the applications of MR imaging of the patellofemoral compartment. Axial plane images are the most informative for abnormalities of this compartment. The role of MR imaging in the evaluation of the medial synovial plica and in the detection of chondromalacia is discussed. MR imaging can reliably detect and delineate the complex of injuries associated with patellar dislocations and valgus hyperextension.

Cartilage Diseases↗
PubMed1993

Evaluation of chondromalacia of the patellofemoral compartment with axial magnetic resonance imaging.

Axial magnetic resonance (MR) imaging of the patellofemoral compartment was performed in 75 patients with arthroscopic correlation. Proton density and T2(2500/20/80) weighted images were obtained in all patients. Chondromalacia in stages I and II could not be reliably identified with MR imaging. For the evaluation of stage III and IV chondromalacia, the accuracy of MR was 89%. Focal or diffuse areas of increased or decreased signal alterations of the hyaline cartilage without a contour deformity or cartilaginous thinning do not correlate reliably with arthroscopic staging of chondromalacia. A normal signal intensity is no assurance that softening of the cartilage is not present. The most reliable indicators of chondromalacia are focal contour irregularities of the hyaline cartilage and/or thinning of the hyaline cartilage associated with high signal intensity changes within frank defects or contour irregularities with T2-weighted images. The poor MR-arthroscopic correlation in earlier stages of chondromalacia may be due in part to the subjective basis of the arthroscopic diagnosis. In conclusion, stage I and II chondromalacia of the patellofemoral compartment cannot be reliably evaluated with MR imaging. Stage III and IV chondromalacia is reliably evaluated with MR using the combination of proton density and T2-weighted images.

Arthroscopy↗
PubMed1993

Prospective evaluation of patients with suspected hip fracture and indeterminate radiographs: use of T1-weighted MR images.

To assess the diagnostic efficacy of T1-weighted magnetic resonance (MR) images when findings on radiographs of the hip are indeterminate, 20 patients with suspected hip fracture and indeterminate radiographs were prospectively evaluated. MR imaging was performed with surface coil technique; one coronal T1-weighted (repetition time msec/echo time msec = 400/19) MR image was obtained. The total charge for the examination was $448 (compared with the following usual charges: radionuclide bone scan, $455; tomography, $299; and computed tomography, $797). When MR imaging and clinical outcome were used as the standard of reference, the prospective accuracy of MR imaging in diagnosis of the presence or absence of hip fracture was 100% (20 correct diagnoses). All MR studies were diagnostic. Of the 13 patients with fracture (eight with trochanteric and five with subcapital fracture), 10 patients (77%) underwent surgery and three patients (23%) received conservative treatment. T1-weighted MR images can enable diagnosis or exclusion of hip fracture whenever radiographs are indeterminate. The imaging time is approximately 7 minutes, and the cost of the examination can be made competitive with costs of other advanced imaging examinations.

Aged↗
PubMed1993

Femoral MR angiography versus conventional angiography: preliminary results.

PURPOSE: To develop a bilateral femoral magnetic resonance (MR) angiographic examination that would include the aortic bifurcation to the ankle. MATERIALS AND METHODS: Thirty-seven patients underwent conventional angiography and the bilateral femoral MR angiographic examination. Two-dimensional time-of-flight angiography was used for all studies. RESULTS: The femoral MR angiogram could have replaced the conventional angiogram in 57% of patients (21 of 37). In 43% of patients (16 of 37), the femoral MR angiogram could not have replaced the conventional angiogram. Reasons for diagnostic failure with femoral MR angiography included artifact from vascular clips (n = 8) or prosthetic joints (n = 3), overlooked distal aortic stenosis (n = 1), and suboptimal definition of vessels (usually trifurcation vessels) owing to various causes (n = 8). Seven of the patients in this group had bypass grafts. CONCLUSION: Some of the current limitations of femoral MR angiography could be avoided by supplemental duplex sonography around prostheses and vascular clips. The other limitations will require advances in MR imaging techniques.

Aged↗
PubMed1993

Large-caliber (24-28-F) catheters for radiologically guided percutaneous procedures.

A catheter set originally designed as a system for placement of large thoracostomy tubes with the Seldinger technique and sequential coaxial dilations was used to place 31 catheters in 28 patients. Either computed tomographic (CT) (n = 25) or fluoroscopic (n = 3) guidance was used. The tubes were 28 F (n = 13) and 24 F (n = 18). The tubes were successfully placed in 27 of 28 patients (96%), with the infection processes completely resolved in 22 of 25 patients (88%). Use of the system is simple and safe. These large catheters may be useful for cure of processes that do not respond to drainage with smaller tubes.

Catheterization↗
PubMed1992

Case report 757: Giant cell tumor of rib.

A case of the rare occurrence of conventional GCT in a rib is presented. Due to its radiological aggressivity, the possibility of a MGCT was entertained clinically, and preoperative chemotherapy and radiation therapy were given. The literature on giant cell tumors of the ribs is reviewed, and their distinction from primary MGCT and other giant-cell-containing lesions is discussed.

Adult↗
PubMed1992

Hepatic cavernous hemangiomas: simple diagnostic sign with dynamic bolus CT.

Many hepatic hemangiomas are discovered incidentally during incremental dynamic bolus computed tomography (CT). To meet the established criteria for diagnosis with CT, however, a second CT examination with single-level dynamic bolus imaging is necessary. A prospective evaluation was performed to examine a simple sign that may be used to diagnose cavernous hemangiomas during incremental dynamic bolus CT. This sign is the visualization of foci of globular enhancement within the hemangioma, analogous to areas of puddling of contrast material seen at angiography. A total of 34 lesions in 21 patients demonstrated foci of globular enhancement. Of the 34 lesions, 32 (94%) proved to be hemangiomas. All 21 patients underwent confirmatory evaluation. Foci of globular enhancement seen during dynamic bolus CT are a strong indication that the lesion is a cavernous hemangioma. This diagnostic sign may obviate further, more expensive imaging studies.

Diatrizoate Meglumine↗
PubMed1992

Venous stenoses in patients who undergo hemodialysis: treatment with self-expandable endovascular stents.

During a 32-month period, 25 modified self-expandable endovascular stents were placed in 20 hemodialysis access sites to treat 21 stenoses and four occlusions in 19 patients. All stenoses were initially dilated with a high-pressure balloon. The initial success rate was 90% (18 of 20 access sites). The stents were patent from 0 to 960 days (mean duration of follow-up, 309 days). At 2 years follow-up, the patency rates were as follows: primary, 25%; secondary, 34%; and tertiary, 42%. The morbidity rate associated with this procedure was 15% (three of 20 sites); the mortality rate, 5% (one of 19 patients). All five complications (graft or native-vein thrombosis [n = 2], nerve deficits [n = 2], and death secondary to sepsis [n = 1]) occurred in three patients early in the study, before the use of prophylactic antibiotics and refinements in technique. The best results occurred in patients in whom the stenosis or occlusion affected a large vein that had no acute angle and was away from venous confluences such as the femoral and iliac regions.

Constriction, Pathologic↗
PubMed1992

Menisci of the knee: radial MR imaging correlated with arthroscopy in 259 patients.

Similar to arthrograms, radial plane magnetic resonance (MR) images of the knee provide cross-sectional images of the menisci that are perpendicular to the long axis of the meniscus. The authors evaluated 259 consecutive patients who underwent MR imaging of the knee and arthroscopy. Radial multiplanar gradient-recalled-echo imaging was performed--with repetition time of 700 msec, echo times of 12 and 31 msec (700/12, 31), and a flip angle of 20 degrees--as well as sagittal spin-echo imaging (2,500/20, 80). The radial and sagittal images were interpreted separately and then in combination, and findings were compared with arthroscopic reports. There was no statistical difference between the interpretations of the radial and sagittal images in the evaluation of the menisci. When the interpretations of the radial and sagittal images were combined, the sensitivity and specificity improved slightly. The radial images increased the conspicuity of meniscal tears but at the expense of anatomic detail. The sagittal images enabled better evaluation of the meniscocapsular attachment region and some flap tears of the meniscal free edge. The interpretive accuracies of the combination of sagittal and radial images were 92% and 93% for the medial and lateral menisci, respectively.

Adult↗
PubMed1992

Long bicipital tendon of the shoulder: normal anatomy and pathologic findings on MR imaging.

The tendon of the long head of the biceps muscle (long bicipital tendon) has a complex course from its muscle belly to its insertion onto the supraglenoid tubercle/glenoid labrum. It is stabilized by numerous tendinous and ligamentous structures and is, in turn, partly responsible for maintenance of normal glenohumeral function. In this report we describe the anatomy of this tendon, correlating high-resolution MR images with cryomicrotome sections. We illustrate typical MR findings in pathologic conditions affecting the long bicipital tendon sheath, the substance of the tendon, and finally the tendon position.

Chondromatosis, Synovial↗
PubMed1992

Biliary complications related to laparoscopic cholecystectomies: radiologic diagnosis and management.

The purpose of this study was to review the radiologic presentations and management of biliary complications related to laparoscopic cholecystectomies. Additionally, a computed tomography (CT) evaluation of asymptomatic postsurgical patients was performed to determine the uncomplicated appearance of the gallbladder fossa. Over a 24-month period 23 biliary complications were seen in patients who underwent laparoscopic cholecystectomies (group 1). Twenty asymptomatic patients were examined with unenhanced CT examinations after laparoscopic cholecystectomy (group 2). Twenty patients in group I had bilomas located in the gallbladder fossa (n = 9), subhepatic (n = 7) and subphrenic (n = 2) spaces, and diffusely distributed in the peritoneal cavity (n = 2). The bile leaks were presumed to have been proved to be from the cystic duct (n = 19), right hepatic duct (n = 1), and common bile duct n = 3) injuries and leaks. Fourteen drains were placed percutaneously using CT (n = 12) or sonographic (n = 2) guidance, and in two cases drains were placed surgically. The duration of catheter drainage average 11.3 days. Six patients underwent endoscopic retrograde cholangiopancreatography (ERCP) procedures, including sphincterotomy (n = 6) and stent placement (n = 3). Patients who were treated with a drain or ERCP procedures or who were managed conservatively all recovered without the need for additional surgery. In five cases, the bile cultures were positive for multiple organisms. Three patients underwent surgical repairs for disrupted common bile ducts. In group 2 CT examinations showed minimal fluid densities in all patients. No evidence of distinct, well-demarcated fluid collection was seen in any of the 20 patients. (ABSTRACT TRUNCATED AT 250 WORDS)

Bile↗
PubMed1991

Spontaneous perinephric hemorrhage: imaging and management.

We report on 10 patients with spontaneous perinephric hemorrhage associated with underlying disease, including renal cell carcinoma (5), angiomyolipoma (2), malignant melanoma (1), periarteritis nodosa (1) and severe portal hypertension (1). The etiology could not be identified with computerized tomography (CT) in 5 cases (50%), including 2 renal cell carcinomas, 1 angiomyolipoma, 1 periarteritis nodosa and 1 portal hypertension. Arteriography demonstrated underlying lesions in 4 of these 5 cases (80%) including the case of vasculitis. CT combined with magnetic resonance imaging is accurate for the diagnosis of spontaneous perinephric hemorrhage but the underlying pathological condition is often undetectable in the acute phase due to the perinephric blood. CT should be the first study performed if this diagnosis is suspected. Arteriography is recommended if a renal mass is not detected. If a mass is not identified with these 2 imaging studies and the patient is clinically stable, followup thin slice CT should be performed.

Adult↗
PubMed1991

Deposition of calcium pyrophosphate dihydrate crystals in the ligamentum flavum: evaluation with MR imaging and CT.

Four patients had spinal canal stenosis associated with deposition of calcium pyrophosphate dihydrate within the ligamentum flavum. Radiologic evaluation was performed with magnetic resonance imaging or computed tomography, and surgery was performed on all four patients. Pathologic examination of the surgical specimens demonstrated deposits of calcium pyrophosphate crystals within the ligamentum flavum. Focal enlargement of the ligamentum flavum was present in the cervical spine (n = 1), while a more diffuse, bilateral enlargement was identified in the lumbar spine (n = 3). Enlargement of the ligament either caused or was a component of spinal stenosis that caused neurologic signs or symptoms. Three of the patients had evidence of calcium pyrophosphate deposition elsewhere. Deposition of calcium pyrophosphate dihydrate within the ligamentum flavum causing either focal or diffuse enlargement can be associated with significant spinal stenosis.

Aged↗
PubMed1991

Meniscal tears diagnosed with MR imaging versus arthroscopy: how reliable a standard is arthroscopy?

Arthroscopy of the menisci is considered the standard by which all noninvasive imaging procedures of the knee are measured. To better recognize the accuracy and relevance of arthroscopic correlation, a study was done in 254 consecutive patients who underwent both magnetic resonance (MR) imaging of the knee and arthroscopy. If interpretation of arthroscopic findings disagreed with MR findings, the arthroscopic videotapes were reviewed. Seventeen errors occurred in interpretation, resulting in false-positive MR images. Nine of these errors (53%) were associated with lines of high signal intensity that reached the articular surface of the posterior horn, an area incompletely seen on the arthroscopic videotapes. Two errors (12%) occurred in postmenisectomy abnormalities that the arthroscopist believed were not clinically significant; the six other errors (35%) occurred in high-signal-intensity alterations in either the free edge or the entire meniscal substance that did not correlate with clinically significant tears. Thirty-two errors occurred in interpretation, resulting in false-negative MR images. Fifteen of these errors (47%) occurred in small tears that did not require meniscectomy.

Arthroscopy↗
PubMed1991

MR imaging in fibromatosis: results in 26 patients with pathologic correlation.

Fibromatoses are a diverse group of soft-tissue lesions that have been inconsistently categorized and treated. The purpose of our study was to establish the range of appearances of fibromatoses on MR images and perform a pathologic correlation to explain the variable signal-intensity patterns. During a 3-year period, 26 patients with deep fibromatoses were examined with MR. The MR images were evaluated for signal-intensity characteristics, and findings were correlated retrospectively with the pathologic diagnoses. The results showed that the MR appearance of fibromatoses is similar to that of other soft-tissue lesions, and the signal intensities vary greatly from lesion to lesion and within lesions themselves. The fibromatoses were either hyperintense, isointense, hypointense, or of mixed signal intensity relative to adjacent skeletal muscle. The hypointense areas appear to be zones of hypocellularity and dense collagen deposition. Microscopically all of the lesions invaded adjacent structures, but the MR appearances of the margins varied and were judged to be well demarcated (n = 14), intermediate (n = 5), or poorly demarcated (n = 6). Our experience shows that fibromatoses have a variable MR appearance no different from that of other soft-tissue lesions, and this variability reflects the composition and cellularity of the lesions.

Adult↗