PubMed Health⌕ Search

Biomedical subjects

A R Moody

Publications and source records attributed to A R Moody.

17 recordsLinked to original sources
PubMed1998

Role of magnetic resonance angiography for assessment of abdominal aortic aneurysm before endoluminal repair.

BACKGROUND: A detailed knowledge of the morphology of the aorta and iliac arteries is an important prerequisite for successful endoluminal abdominal aortic aneurysm (AAA) repair. The best method of preoperative evaluation remains to be determined. METHODS: A prospective study was undertaken between January 1994 and July 1995 to assess the ability of computed tomography (CT), magnetic resonance angiography (MRA), colour duplex imaging and intra-arterial digital subtraction angiography (IA-DSA) to visualize AAA morphology. RESULTS: Eighty-two consecutive patients (64 men, 18 women) with AAA were assessed with MRA, contrast-enhanced CT, colour duplex imaging and IA-DSA. Median age was 74 (range 59-87) years and median AAA diameter was 5.7 (range 3.5-9.7) cm. Five patients were unable to tolerate CT or MRA examination. Seventy-seven patients underwent both CT and MRA. Of these, 55 also had a colour duplex scan and 32 underwent arteriography. The scans were assessed by an independent blinded observer. MRA was significantly better (P < 0.01) at visualizing AAA morphology compared with CT and colour duplex imaging. There was no statistically significant difference between MRA and arteriography. CONCLUSION: MRA is useful in patient selection for endoluminal AAA repair, as it avoids use of iodinated contrast medium and ionizing radiation.

Aged↗
PubMed1998

Lower-limb deep venous thrombosis: direct MR imaging of the thrombus.

PURPOSE: To determine the feasibility of diagnosing deep venous thrombosis (DVT) with direct three-dimensional magnetic resonance (MR) imaging of the thrombus. MATERIALS AND METHODS: Eighteen patients with proved DVT at conventional venography were evaluated with a magnetization-prepared three-dimensional blood- and fat-suppressed MR imaging sequence. The presence and extent of thrombosis on the MR images were compared with the findings at conventional venography. RESULTS: At MR imaging, DVT was visualized in 17 of the 18 patients. MR imaging demonstrated greater proximal extent of the thrombosis in four patients, asymptomatic contralateral thrombosis in one, involvement of the deep femoral vein in five, and involvement of the superficial venous system in three. CONCLUSION: Direct MR imaging of clots appears capable of demonstrating venographically diagnosed DVT. This MR imaging technique is noninvasive, quick, and repeatable and allows a survey of the whole lower-limb venous system. Detection of thrombosis relies on the formation of methemoglobin, which appears to be sufficiently rapid to allow use of this technique in the clinical setting. Changes in the signal from clot over time may allow estimation of the age of the thrombus.

Feasibility Studies↗
PubMed1997

Dynamic T1 measurement using snapshot-FLASH MRI.

The application of an inversion-recovery snapshot FLASH (fast low-angled shot) imaging sequence to the dynamic measurement of monoexponential T1 relaxation was investigated. The effect of (a) a reduction in the overall sequence repetition time, and (b) an increase of the read-pulse flip angle, on the measurement of T1 was analyzed. The error in T1 introduced by these factors is calculated, and a fuller analysis that takes them into account is presented. Data from a phantom are used to confirm this analysis. The magnitude of the errors is illustrated by measuring myocardial T1 in patients with acute ischaemic heart disease during the injection of a bolus of the contrast medium gadobenate dimeglumine. Overall, there was a 10% difference between the T1 values when the approximate and exact solutions were used; this was statistically significant. However, the difference was on average 25% for patients with a high heart rate (because of the shorter sequence-repetition time) in areas of infarcted myocardium (because of the longer T1).

Contrast Media↗
PubMed1997

Magnetic resonance pulmonary angiography and direct imaging of embolus for the detection of pulmonary emboli.

RATIONALE AND OBJECTIVES: The authors developed a two-dimensional breathhold magnetic resonance (MR) technique for the direct imaging of pulmonary emboli. METHODS: In vitro MR imaging was performed to demonstrate the potential generation of clot-blood contrast by in vivo pulmonary embolism (PE). A two-dimensional magnetization prepared gradient-echo (turbo-FLASH) breathhold technique was designed to directly image intravascular emboli by the selective nulling of the blood signal. A turbo-FLASH pulmonary angiographic breathhold sequence was used to provide spatial localization of detected emboli. Thirteen patients with suspected PE were studied; 6 patients underwent conventional pulmonary angiography (CPA) and the remaining 7 had diagnoses based on findings from other studies. RESULTS: In vitro study of blood clot demonstrated an initial rise and then fall in T1 sufficient to generate clot-blood contrast after eight days of clot formation. All patients with CPA or alternative study evidence of PE were diagnosed as positive with direct embolus imaging MR. There were no false-positive diagnoses. Three additional emboli were detected using the MR technique compared with CPA. The MR pulmonary angiographic sequence provided a useful road map for localization of intravascular emboli but was less sensitive for PE detection than the embolus imaging technique. CONCLUSIONS: The direct imaging of PE is feasible using a simple two-dimensional breathhold technique.

Adult↗
PubMed1997

Comparison of transcranial color-coded sonography and magnetic resonance angiography in acute stroke.

BACKGROUND AND PURPOSE: We sought to compare the ability of transcranial color-coded Doppler sonography (TCCS) and magnetic resonance angiography (MRA) to identify circulatory changes that occur after acute stroke. METHODS: Forty-four patients with a clinical diagnosis of acute stroke were studied with both TCCS and MRA within 24 hours of stroke onset. The appearances of all vessels identified on MRA were divided into three categories: normal, attenuated, and absent vessels. The basal cerebral arteries were identified with the use of TCCS, and their velocities were measured with pulsed-wave Doppler. The side-to-side asymmetry was calculated and expressed as an asymmetry index. RESULTS: Five patients could not be studied with TCCS because of lack of a suitable acoustic window. An additional 4 patients were too restless to tolerate MRA scanning. Three patients had intracerebral hemorrhages, 2 patients had intracerebral gliomas, and the remaining 30 patients had cerebral infarctions. In the group of patients with acute cerebral infarction, TCCS identified 10 patients with normal asymmetry indices, 1 patient with an increased asymmetry index, 9 patients with decreased asymmetry indices, and 10 patients with occlusion of the symptomatic middle cerebral artery (MCA). MRA identified 8 normal angiograms, 6 patients had attenuated MCA branch vessels, 4 patients had MCA branch occlusions, 2 angiograms demonstrated MCA main stem attenuation, and 10 angiograms showed MCA occlusion. CONCLUSIONS: TCCS and MRA are both noninvasive techniques that can be used to study the acute stroke patient. They both yield information regarding the pathophysiology of acute stroke and may be useful techniques in deciding on therapeutic interventions. The findings agree closely with each other, and these techniques may be useful in the long-term follow-up of stroke patients.

Acute Disease↗
PubMed1995

Optimization of a breath-hold magnetic resonance gradient echo technique for the detection of interstitial lung disease.

RATIONALE AND OBJECTIVES: A rapid gradient echo technique was optimized to allow breath-held imaging of the lung parenchyma. The ability of this sequence to detect interstitial lung disease was then compared with high resolution computed tomography. METHODS: A Turbo-FLASH gradient echo sequence (repetition time [TR] 4.7, echo time [TE]2) was optimized using four volunteers. The parameters varied, including flip angle, inversion time, slice thickness, and number of measurements per unit time. The effect on signal to noise ratio of lung inflation and position within the lung were also studied. The optimized sequence was then compared with high resolution computed tomography in five patients being investigated for interstitial lung disease. RESULTS: Greatest signal was achieved using no inversion prepulse. This allowed up to six measurements, each with two acquisitions, during a single breath-hold. Optimum signal to noise ratio was achieved using a flip angle of 10 degrees with a 20-mm slice thickness, although a 10-mm slice was felt to be preferable for clinical use. Greatest signal to noise ratio was generated in the posterior aspect of the lung in full expiration. Comparison of the optimized magnetic resonance imaging technique with high resolution computed tomography showed no significant difference (P = 0.17) when assessing the proportion of diseased to normal lung. CONCLUSIONS: Using standard magnetic resonance software and hardware, it has been possible to use a breath-hold sequence that allows detection and quantification of interstitial lung disease.

Adult↗
PubMed1994

Digital sialography: imaging and intervention.

Digital subtraction imaging (DSI) has been widely used in angiography but less commonly applied to sialography. Over a 3-year period 109 patients referred for sialography, 42 males and 67 females with a mean age of 44 years (range 8-85 years), were examined using a digital subtraction imaging technique. 13 patients went on to have an interventional procedure, stone removal or duct dilatation. The role of DSI imaging in sialography and its use in facilitating interventional procedures on the salivary glands are discussed.

Adolescent↗
PubMed1993

Atypical hepatic hemangioma: a suggestive sonographic morphology.

A retrospective review of the sonographic appearances of 29 proved atypical hemangiomas in 29 patients and a prospective study of the predictive capacity of these features were performed. The main confirmatory imaging examinations were computed tomography and technetium-labeled red blood cell radioisotope scanning with single photon emission computed tomography. The retrospective review showed that all tumors were solid. Twenty-seven tumors had an echogenic border, seen as a thick echogenic rind (n = 15) and a thin rim (n = 12). Unlike typical hemangiomas, which have a uniformly increased echogenicity relative to normal liver, all 29 tumors had an internal echo pattern that was at least partially hypoechoic. These morphologic criteria (a solid tumor with an echogenic border and partially hypoechoic internal pattern) were then prospectively applied to all hepatic tumors detected with sonography during a 6-month period. Fifteen lesions with these features were identified from among more than 5,000 abdominal scans. Twelve of these lesions were confirmed as, and two were presumed to be, cavernous hemangiomas; in one lesion, the diagnosis was false-positive. Recognition of these atypical features should increase suspicion of the presence of hemangiomas on sonograms.

Adult↗
PubMed1992

Non-Hodgkin lymphoma in the porta hepatis after orthotopic liver transplantation: sonographic findings.

The sonographic appearances of primary non-Hodgkin lymphoma developing in the porta hepatis in three patients soon after hepatic transplantation were reviewed. The lymphomas appeared as large hypoechoic masses encasing vital portal structures--the hepatic artery and the common bile duct--in all three cases and displacing the portal vein in two. The liver was only locally involved. All patients presented with jaundice soon after transplantation (average interval, 6.3 months). Rapid tumor progression caused hepatic infarction, necessitating retransplantation in two patients. The third patient died shortly after diagnosis. The authors believe this complication will be seen increasingly as liver transplantation becomes more common. Non-Hodgkin lymphoma should be considered when an obstructing mass is found in the porta hepatis, even when the time interval since transplantation is short.

Common Bile Duct↗
PubMed1992

Gastroepiploic veins: CT appearance in pancreatic disease.

The frequency with which gastroepiploic vein (GEV) enlargement was seen on CT and its relevance to disease of the portal venous system associated with pancreatic disease were studied. We performed a retrospective study of 50 patients with proved pancreatic disease and another 50 patients without such disease. The CT examinations were done in incremental dynamic fashion after a bolus injection of contrast medium. Scans were evaluated for collateral channel formation, including GEV enlargement, and for involvement of the portal venous system by pancreatic disease. Part of the GEV arcade was visible in 36 patients without pancreatic disease, and on average measured 3.2 mm in diameter (range, 1-5.5 mm). GEV enlargement was visible in 62% of the patients with disease; 16% demonstrated a vessel 6 mm or more in diameter. Thirty-four percent of the patients with disease had portal venous complications: 26% had isolated splenic vein involvement, 2% had isolated portal vein involvement, and 6% had a combination of splenic and portal vein involvement. Of the patients with splenic vein disease, 81% had collateral channel formation, 50% of them demonstrating isolated GEV enlargement. Patients with splenic vein disease due to acute pancreatic disease had a much higher instance of GEV enlargement (83.3%). Collateral vessels are commonly seen on CT scans of patients with splenic vein disease and most often occur via enlarged GEVs. Acute pancreatic disease is frequently associated with GEV enlargement, suggesting that the latter represents an early response to splenic vein disease. In contrast, multiple collateral pathways tend to develop in patients with chronic pancreatic disease.

Adult↗
PubMedDate not supplied

CT monitoring of therapy for meconium ileus.

Meconium ileus equivalent is a common complication of cystic fibrosis in the postneonatal period. Because of the added risks of surgery in these patients, conservative management is preferred. We describe here a method of monitoring the conservative treatment of this condition using CT and suggest that its application will reduce the need for potentially dangerous surgical intervention.

Adolescent↗