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Query: UMLS:C0851184 (thinning)
 11,252 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To evaluate the magnetic resonance imaging (MRI) features of chronic myocardial infarction (MI), 22 patients and several normal volunteers were studied with a 0.35-T cryogenic imaging system. The MIs were 9 months to 16 years old. The patients also had either left ventriculography (17 patients) or two-dimensional echocardiography (17 patients). At least one abnormality indicative of prior infarction was demonstrated on MRI in 20 of the 22 patients. Wall thinning was seen in 20 patients; in six of these, the thinning resulted in aneurysm formation. The other 14 patients had sufficient residual wall thickness to permit measurement of T2 relaxation times and MR signal intensity in the infarcted region. Ten of these 14 patients demonstrated low intensity and shortened T2 of the thinned segments (mean T2 = 28.7 msec) compared to adjacent normal myocardium (mean T2 = 45.4 msec) and to the myocardium of volunteers (mean T2 = 41.3 msec). The percentage of difference in intensity between thinned and normal myocardium was greater on 56-msec-TE images (98.2%) than on 28-msec-TE images (46.1%). In the other four patients, no difference in intensity of the myocardium was perceptible in the thinned region of the myocardial wall. Thus MRI shows regional wall thinning at the site of prior MI. In some patients, the chronic infarct is characterized as decreased spin-echo signal intensity and shortened T2 consistent with replacement of myocardium by fibrous scar.
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PMID:Magnetic resonance imaging of chronic myocardial infarcts in man. 348 81

Positron emission computed tomography (PET) is regarded an excellent technique for quantitative measurements. However, its accuracy is related to the spatial resolution of the system. The relation between myocardial wall thicknesses as measured by X-ray CT or MRI and the radioactivity as measured using PET was studied in 37 patients. 1. In patients with transmural infarction, the infarcted myocardium was imaged as a region of low radioactivity. However, the myocardium usually exhibited wall thinning, so that partial volume effects must be taken into account in evaluating the radioactivity. 2. In the infarcted regions, the regions of the low radioactivity tended to be larger than those of wall thinning. 3. There were cases with the regional low radioactivity without wall thinning in myocardial infarction and in hypertrophic cardiomyopathy. Because patients with myocardial infarction frequently had regional wall thinning, it seems necessary to correct partial volume effects for the infarcted regions which differ from the normal. It was concluded that, to estimate regional myocardial blood flow or metabolism using PET, it is necessary to supplement another morphological diagnostic method to evaluate myocardial wall thickness.
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PMID:[Problems related to tracer concentration and wall thickness: pitfalls in positron CT diagnosis]. 350 33

Thirty of 32 cases with cardiac rupture (CR) complications in the myocardial infarction were found out of a total of 91 cases of acute myocardial infarction (AMI). The mean age of the ruptured group in females was significantly younger than that of the non-ruptured group. Twenty-one cases showed free wall rupture of the left ventricle, six perforation of ventricular septum and three double rupture. All cardiac ruptures occurred in cases of transmural infarction. The age of AMI was histologically estimated. Nine cases complicated within the first 24 hours of AMI showed rupture of the left anterior wall. CR in the periphery within the infarct occurred at any time during the first week after onset, and cases of the central rupture were increased in number after the 3rd day of AMI. Pathologic findings indicated that elevated wall tension was considered to be most closely related to the cause of CR. Thirty two cases of CR were classified into three types: (1) blowout type, (2) hemorrhagic dissecting type, and (3) thinning-with-rupture type. Hemorrhagic dissecting type was characterized by multiple endocardial ulcers and fissure canals extending from the ulcer with hemorrhage in the surrounding myocardium. Complex fissure was seen in two cases of this type.
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PMID:Classification of cardiac rupture complicated in myocardial infarction. Pathological study of 32 cases. 363 Jul 5

In vivo gated magnetic resonance (MR) imaging was performed in 12 dogs immediately after occlusion of the left anterior descending coronary artery and serially up to 5 hours and again between 4 and 14 days. This was done to evaluate the appearance of acute myocardial infarcts and to determine how soon after coronary artery occlusion MR imaging can demonstrate the site of acute myocardial ischemia. In nine dogs with postmortem evidence of myocardial infarction, regional increase of signal intensity of the myocardium was present by 3 hours after coronary artery occlusion and conformed to the site of myocardial infarct found at autopsy. The signal intensity on T2-weighted images of the infarcted myocardium was significantly greater than that of normal myocardium at 3, 4, and 5 hours after occlusion. The T2 (spin-spin) relaxation time was significantly prolonged in the region of myocardial infarct at 3, 4, and 5 hours postocclusion compared with normal myocardium. Myocardial wall thinning and increased intracavitary flow signal were found in six dogs with comparable pre- and postocclusion images in late systole.
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PMID:Early-phase myocardial infarction: evaluation by MR imaging. 370 48

The ability of magnetic resonance imaging (MRI) to detect and localize healed myocardial infarction (MI) was assessed. Seventeen consecutive patients with healed MI assessed by biplane contrast ventriculography underwent MRI using oblique imaging planes. Seven normal subjects underwent MRI as controls. In each patient, ventriculography identified regional wall motion abnormalities. MRI, performed with a 0.15-Tesla resistive magnet and oblique imaging planes relating to the left ventricle, detected zones of regional wall thinning conforming to the wall motion abnormalities localized by ventriculography in 16 patients. In these patients, adjacent areas of intact myocardium were identified in areas shown by ventriculography to be normal. The left ventricular wall thickness at the site of MI was significantly less than adjacent noninfarcted myocardium (p less than 0.001) and normal hearts (p less than 10(-6)). The ratio of the thickness of the infarct to adjacent normal wall averaged 0.40 (range 0.22 to 0.62). MRI could differentiate healed MI from adjacent noninfarcted myocardium and normal hearts.
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PMID:Assessment of left ventricular wall thickness in healed myocardial infarction by magnetic resonance imaging. 381 50

To elucidate the pathophysiology of dilated cardiomyopathy (DCM), the relationship of two-dimensional echocardiographic wall motion abnormalities (asynergy) to histopathological findings was evaluated in autopsied patients including seven with DCM, five with old myocardial infarction (OMI) and three with the normal heart. The DCM cases were classified morphologically in two groups, namely four of type I and II and three of type III, according to Shozawa's classification. Three short-axis views of the left ventricle were divided into 19 segments; the wall motion was assessed visually and classified as normal motion, hypokinesis, akinesis and dyskinesis. The postmortem specimens were immersed in 10% formalin; transverse sections and wall divisions were prepared corresponding to the two-dimensional echocardiographic views, and the area of each segment was determined by a computer planimetry excluding the papillary muscles and trabeculae. Fibrosis (%) was measured histologically by the point counting method with light microscopy. The results were as follows: In DCM, fibrosis (%) increased with increasing severity of asynergy: 17.1% fibrosis in normal motion; 28.7% in hypokinesis; 40.7% in akinesis and dyskinesis. In OMI, fibrosis (%) also increased with increasing severity of asynergy. On comparison of DCM with OMI, no difference was established relating to fibrosis (%) in the asynergic segments; moreover, in both groups, asynergy was detected more frequently in the segments in which fibrosis (%) exceeded 21%. On comparison of type I+II DCM with type III DCM, fibrosis (%) of type III was significantly less than that of type I+II in the same degree of asynergic segments. Moreover, fibrosis (%) of type I+II tended to be greater in the outer layer than in the inner layer, while fibrosis (%) of type III was evenly distributed throughout the myocardium, or greater in the inner layer than in the outer layer. In type I+II, wall thinning was marked with increasing severity of asynergy; in contrast, these correlations were not observed in type III. In type I+II, a higher fibrotic rate was observed in the left ventricular free wall and an abnormal Q wave appeared frequently on ECG. This tendency was not found in type III. These findings indicate that fibrosis is one of the most important factors in decreasing cardiac muscular contractility in DCM, and suggest that there is a different pathogenesis between type I+II and type III fibrosis.
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PMID:[Two-dimensional echocardiographic recognition of dilated cardiomyopathy: comparison with postmortem studies]. 384 89

Segmental wall motion abnormalities are common in patients with myocarditis. Left ventricular (LV) regional wall motion was assessed in six patients with myocarditis by two-dimensional echocardiography. Some of our patients demonstrated regional thinning of the wall, similar to myocardial infarction. Therefore, segmental wall motion abnormalities with or without regional wall thinning detected by two-dimensional echocardiography cannot be used to differentiate myocarditis from coronary artery disease. Nevertheless, echocardiography can be performed repeatedly and is useful for evaluating the severity of myocarditis by assessing LV regional wall motion abnormalities, changes in LV wall thickness and cardiac pump function during the course of the disease.
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PMID:Echocardiographic assessment of left ventricular wall motion in myocarditis. 384 73

Infarct expansion, the time-related thinning and dilation of an acute transmural infarct, leads to aneurysm formation and cardiac rupture in humans. In this study, the effect of exercise on acute infarct expansion early after myocardial infarction was examined in 129 rats. Ninety rats were exercised on a treadmill for 1.5 hours daily for 1 week beginning on the day of coronary artery ligation; the remaining 39 rats remained in their cages. There was no effect on the prevalence or extent of expansion; specifically, infarct wall thickness, left ventricular diameter and expansion grade (0 to 4+) were similar in the exercise and control rats. There was no difference in infarct size or the number of animals with aneurysmal shape changes in the exercise and control groups. There was no significant difference between the two groups in the histologic finding of intramural hemorrhage, a feature that has been associated with cardiac rupture, and no complete rupture was seen. However, there was a nonsignificant trend toward higher mortality in the exercised group. Thus, the findings of this study suggest that moderate exercise early after myocardial infarction produces no significant detrimental effect on infarct size or left ventricular topography in the rat model.
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PMID:Effect of exercise on acute myocardial infarction in rats. 394 Nov 99

Temporal changes in infarct collagen and left ventricular topography during healing after myocardial infarction were studied in 132 dogs with coronary artery ligation: 8 sham dogs and 13 with no infarction (controls) and 111 with infarction (3 at 1 day, 54 at 2 days, 25 at 7 days, 3 at 2 weeks, 9 at 4 weeks and 17 at 6 weeks). Myocardial hydroxyproline (a marker of collagen) was measured by spectrophotometry and pathologic infarct size, arteriographic occluded bed size and topography by computerized planimetry of weighed left ventricular rings. Over 6 weeks, hydroxyproline was unchanged in normal regions (average 4.20 mg/g dry weight) but increased progressively between 7 days and 6 weeks (9.94 versus 55.55 mg/g, p less than 0.001) in infarct zones. Progressive infarct contraction occurred over 6 weeks, with infarct size at 6 weeks being 40% less than at 2 days (9.7 versus 16.3% of the left ventricle, p less than 0.001), although total infarct hydroxyproline was directly related to infarct size at each time period (r = 0.73 to 0.81, p less than or equal to 0.05). Significant (p less than or equal to 0.05) left ventricular topographic changes in infarct hearts compared with control hearts included: 1) increase in cavity area (5.0 versus 3.9 cm2), endocardial circumference (8.8 versus 7.4 cm) and expansion index (infarct/normal endocardial segment length, 1.21 versus 1.02) by 7 days; and 2) decrease in thinning ratio (infarct/normal wall thickness, 0.71 versus 0.98) by 6 weeks. Also, compared with 2 day infarcts, by 6 weeks infarct area was decreased (1.8 versus 3.4 cm2) and the noninfarcted segment length increased (6.9 versus 5.4 cm). Changes in hydroxyproline and topography were similar for anterior (n = 54) and posterior (n = 57) infarcts. Thus, healing in canine infarcts is associated with cavity dilation and infarct expansion within 7 days followed by infarct contraction and thinning by 6 weeks, whereas collagen increases between 7 days and 6 weeks. Collagen deposition in expanded and thinned infarct segments explains the permanent regional shape distortion associated with ventricular aneurysms.
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PMID:Healing after myocardial infarction in the dog: changes in infarct hydroxyproline and topography. 394 Dec 23

Nuclear magnetic resonance imaging has emerged in the past few years as a completely noninvasive method for medical imaging of internal organs. Because of the loss of signal intensity by motional nuclei (hydrogen) using most proton imaging techniques, flowing blood within the cardiovascular system generates little or no signal and consequently there is high natural contrast between blood and the walls of blood vessels or cardiac chambers. However, motion during imaging also complicates cardiac imaging because signal is lost from the nuclei in the moving cardiac structures. Consequently electrocardiographic gating of data acquisition is required for nuclear magnetic resonance imaging of the heart. Distinct advantages of nuclear magnetic resonance imaging in relation to other imaging modalities are good contrast between soft tissues and the capability for characterization of specific tissues by estimation of magnetic relaxation times. Early in vitro studies measuring relaxation times of myocardial tissue samples of excised hearts indicate that nuclear magnetic resonance imaging will be capable of discriminating infarcted from normal myocardium. Recent studies using electrocardiographically gated nuclear magnetic resonance imaging of dogs with acute infarction showed the infarct as a region of high intensity on spin-echo images. Initial clinical experience with electrocardiographically gated nuclear magnetic resonance imaging (0.35 tesla) in patients has clearly defined internal cardiac anatomy without the use of contrast media. This technique has demonstrated the consequence of previous myocardial infarction such as regional wall thinning, aneurysm, thrombus and contractile dysfunction, a number of pericardial abnormalities and the morphology of hypertrophic and congestive cardiomyopathies.
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PMID:Assessment of cardiac anatomy using nuclear magnetic resonance imaging. 396 36


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