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Perfusion Miocardical with Nuclear Magnetic Resonance: Gadolinium in First-Pass and Segmental Motility for the Diagnose of the Severe Coronary Disease

Obregón Ricardo; Gonzalez Rubén; Gutierrez Patricia; Pelozo Raúl; Farías Eduardo; Alvarenga Pablo; Badaracco Jorge

Institute of Cardiology "Juana F. Cabral"
Corrientes, Argentina

Introduction
Objectives
Material and Methods
Results
Discussion
Conclusions
References

Introduction

The relationship is known between alteration of the regional parietal motility and the coronary disease. The alterations of the motility can be due to myocardial necrosis or a sufficiently severe isquemia to provoke it. On the other hand, a deficit in the perfusion of the myocardio doesn't always define lesions of the epicardical arteries. Adding both approaches (alteration in the motility and the perfusion) can help us to identify patient with severe coronary disease. The myocardial perfusion evaluated by means of Nuclear Magnetic Resonance Imaging (MRI) with the technique of the first pass of the Gadolinium it is a method in development, the segmental ventricular motility by means of cinema MRI a method of first line is considered by the quality of its images, with the purpose of studying the perfusión and the segmental motilidad with a single method (MRI) and to determine its utility for the diagnosis of coronary lesions you design this protocol.  

Objectives

1) to evaluate of the miocardial perfusion with Gadolinium (in rest) by means of nuclear magnetic resonance and their correlation with the angiography

2) To Compare the segmental parietal motility with the perfusión miocardial in the diagnosis of coronary disease.

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Material and Methods

18 consecutive patients entered with diagnosis of unstable angina, remitted for heart cathetherism, 9 (50%) men, and 9 (50%) women. Presenting a 58±15 year-old age (20-82). Chart 1

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Perfusion sequences: Imaging were performed with a commercially available 1.5-T whole body imaging system (Gyroscan ACS/NT; we used cardiac software. With the patient carrying with breath-hold of 16 seconds took the perfusion images. A slice was used in the short axis at half ventricular level ( papilars muscle). Gadolinium was injected (0.04 mmol/Kg) in the vein right anterocubital in 1-2 seconds (skittle). The used sequences appear in the chart 2.

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Fig. 1.  In the image number 1 it is observed a hipoperfusion septal and lateral lower with commitment of the muscle later papilar. In to the image nº 2 the hipoperfusión is antero septal

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Fig. 1

The segmentary motility was studied with cinema MRI (Echo of Gradient), with four slices in the short axis of the heart achieved with double angulation. Using the ventricular segmentation of 3 territories was defined the suplency of the different coronary arteries classifying them in: descending previous (AD), coronary right (CR) and circumflex (CX) according to the approaches of it SEIZES it (American Society of Echocardiography).

The quality of the studies was classified in three points 1 = excellent, 2 = normal 3 = to regulate

Coronariography: The cathetherism was carried out by means of the technique of Zeldinger. He was defined severe coronary illness to the narrowing of the light from the biggest glass to 70% in some of the biggest coronary artery.

Statistical global: The results were presented in means. In the comparative studies the method of the chi square was used with the test of Fisher for small samples being considered significant a p <0.05. For the analysis you sensibility and specificity the classic formulas were used.

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Results:

The time lapsed between the heart cateterismo and the study of resonance magnetic fué of 4.1±5.8 days. For severe lesion was determined of (AD) it in 7 patients, 6 in the RC and 3 in the Cx

The study of MRI could be carried out in 20 patients, two of them were discarded by bad quality the images. Of the 18 that entered to the study they presented excellent quality of image 8 (44.4%), normal quality 7 (38.9%), and 3 (16.7%) to regulate quality. No patient presented adverse reactions to the Gadolinium.

Motility for MRI: The motility was altered in the territory of AD in 8/18 patients (44.4%), in the territory of the RC 9/18 (50%) and in 6/18 (33.3%) in the CX. When comparing the segmental motility with the coronary lesions we find a sensibility and specificity to detect them in the different territories of AD, RC and CX the 43 and 57%, 100 and 63%, and 67 and 73% respectively.

Perfusion: They were perfusion deficits in 23 segments. The territory of AD it was committed in 12/18 (66.7%), CD 7/18 (38.9%) and CX 1/18 (6%). When comparing the deficits of myocardial perfusion with the coronary lesions the sensibility and specificity diagnostic in the territories of AD and RC fué of 86%-67% and 46%-75% respectively, with a sensibility and global specificity of 76.2% and 60.2% respectively. When considering only the studies of good quality (15 studies) an improvement of the global sensibility of 9.3% was evidenced (76.2 to 85.5%) with an improvement in the global specificity of 5.3% (60.2 to 65.9%). Graph 2. In the territory of the CX 4 patients they presented coronary lesions, without alteration evidences in the perfusion

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Graph 2. Changes of sensibility and dependent specificity of the
quality of the images in the myocardial perfusion with gadolinium

Utility of both approaches: It was observed alteration of the motility and the perfusion in the territory of DA in 6 of 8 patients with coronary lesions in same territory (75%), in the territory of the RC 4/9 (44.4%) and CX in 0/6 . Determining a sensibility and specificity to define severe coronary lesions in AD of 33-61%, and of the RC of 57-100% no patient presented both approaches respectively, in the territory of the circumflex one.

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Discussion

This work presents several limitations. 1) the sample is small 2) The absence of the alteration combination in the motilily with perfusion deficit in the territory of the circumflex one has impeded an appropriate study of this segment. 3) this study compares the myocardial perfusion and the alteration of the motility with the angiography the best comparison would be possibly with other perfusion techniques (SPECT, PET etc.) where the fisiopathology of the ischemia is evaluated from the same point of view. 4) it has not been used pharmacological urgencies to sensitize the method.

Independently of the difficulties previously enumerated in this work the fasility of the heart study it is demonstrated with MRI and the save of the Gadolinium use for the study in patient with coronary disease.

Here the deficit of myocardial perfusion is compared with the alterations of the parietal motility in patient with unstable angina. Previous studies demonstrated that the perfusion defects determine territories with severe coronary lesions in the same way the alterations of the regional parietal motility they coincide with areas ischemia when this it is sufficiently severe. In our population of patient with unstable angina the same number of territories was evidenced with perfusion alteration and of motility in 23 territories (42% of the evaluated total). The alteration in the myocardial perfusion was not always accompanied of contractile alterations, independently of the presence of serious coronary lesions, this disagreement would be to the development of colateral circulation, something that was not evaluated in this opportunity.

In the analysis of the results it was determined that a good image quality (show in 80% of the patients) it improves the sensibility and specificity in the detection of coronary illness a 20 and 7% respectively, the quality of the images is therefore a crucial point in the moment of the final analysis. The alteration of the parietal motility presents a sensibility and global specificity of 68% and 64% respectively in comparison to 56% and 67% demonstrated by the myocardial perfusion. When adding both approaches (motility and perfusion) the sensibility fué of 75% with a specificity of 65%, improving the specificity in the territory of the RC. The biggest discrepacias was possibly evidenced in the territory of the circumflex one due to the mixed coronary suplency (in rest) that presents this territory.

Conclusions

1) the perfusion with Gadolinium, in rest, has bigger sensibility and specificity that the segmental motility for the diagnosis of severe coronary illness.
2) the sum of the perfusion approaches and motility elevated the specificity in the territory of the RC.

 

Questions, contributions and commentaries to the Authors: send an e-mail message (up to 15 lines, without attachments) to image-pcvc@pcvc.sminter.com.ar , written either in English, Spanish, or Portuguese.

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Update
Dic/05/1999