| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
1
Department of Radiology, University Hospital Graz, Auenbruggerplatz 9, A-8036
Graz, Austria.
2
Department of Pediatric Cardiology, University Hospital Graz, A-8036 Graz,
Austria.
Received January 17, 2000;
accepted after revision March 28, 2000.
Address correspondence to G. J. Schaffler.
Abstract
 Top Abstract IntroductionSubjects and MethodsResultsDiscussionReferences |
|---|
SUBJECTS AND METHODS. Twenty-five patients referred because of suspicion of stenosis in the area of former coarctation were prospectively studied with CT angiography and catheter angiography. We determined the morphometric and morphologic findings such as aortic diameter, stenosis, aneurysm, intimal flaps, circumscribed pouch, or arteriosclerotic plaques with 3D reconstructions, using maximum-intensity-projection (MIP) technique and catheter angiography. The results of both techniques were compared. The ratio of the narrowest diameters of the former coarctation and the descending aorta was correlated with the systolic pullback blood pressure gradient in all patients.
RESULTS. The former coarctation was normal in 11 patients, (44%), group A; narrowed in 12 children (48%), group B; and dilated in two children (8%), group C. An intimal flap and a circumscribed pouch were delineated in four subjects. MIP reconstructions and catheter angiography revealed identical results regarding the classification into groups A, B, C; intimal flaps; and circumscribed pouches. Statistical analysis revealed good correlation between the narrowest aortic diameters measured on MIP reconstructions and catheter angiography, whereas no correlation between the systolic pullback blood pressure gradient and the diameter ratio of the former coarctation and the descending aorta was found.
CONCLUSION. CT angiography and 3D reconstructions using MIP represent a reliable noninvasive technique to replace diagnostic catheter angiography in the postoperative care of patients with coarctation and provide the clinician with valuable information concerning further invasive procedures.
|
TopAbstractIntroductionSubjects and MethodsResultsDiscussionReferences |
|---|
Because of the development of helical CT, CT angiography is a promising method for the evaluation of blood vessels [3]. In axial CT slices, the course of complex vascular malformation such as coarctation is not clearly displayed [4, 5]. Becker et al. [5] have shown that three-dimensional (3D) reconstructions were useful in patients with suspected aortic coarctation. In addition, they mentioned that this technique could be useful for noninvasive postoperative followup after surgical repair of coarctation.
To investigate the possible clinical value of 3D reconstructed images of CT angiography, we compared the postoperative results of catheter angiography and maximum-intensity-projection (MIP) reconstructions in former coarctation patients and also correlated radiologic findings with systolic pullback blood pressure gradient obtained by catheter angiography.
|
TopAbstractIntroductionSubjects and MethodsResultsDiscussionReferences |
|---|
All patients underwent routine clinical follow-up, including complete physical examination, especially pulse recording at all four extremities, calculation of systolic blood pressure gradient between the right arm and the right leg, color Doppler echocardiography, and electrocardiography.
In all 25 patients, stenosis in the former coarctation was suspected either in the case of an increased systolic blood pressure gradient between the right arm and the right leg (n = 7) or, in the case of turbulent blood flow, in the postoperative segment of the thoracic aorta during echocardiography (n = 18). Contrast-enhanced helical CT and catheter angiography were performed in all 25 patients with suspected stenosis.
CT angiography was performed from the level of the diaphragm to 3 cm superior to the origin of the great supraaortic vessels, in the caudocranial direction. All subjects were examined with a Somatom Plus 4 scanner (Siemens Medical System, Erlangen, Germany) using a pitch of 1:5, slice collimation of 3 mm, table feed of 4.5 mm, and reconstruction increment of 2 mm. The voltage and tube current were set at 120 kVp and 107 mA. In children younger than 8 years old, tube current was reduced to 50 mA. Depending on age, an average of 49 mL (range, 10-100 mL, 1.5 mL/kg body weight) of a nonionic contrast agent, either Iomeprol (Jopamiro; Gerot, Vienna, Austria) (n = 7) or iopentol (Imagopaque; Nycomed Imaging AS, Oslo, Norway) (n = 18), was injected into an antecubital or forearm vein with an average flow rate of 1.8 mL/sec (range, 4.0-0.4 mL/sec). The individual scan delay was determined after the administration of a test bolus and ranged from 10 to 20 sec. Helical CT data acquisition was performed in one breath-hold. In children younger than 5 years old, helical CT data acquisition was carried out in deep sedation without intubation (midazolam [Dormicum, Roche, Basel, Switzerland], 0.1-0.2 mg/kg body weight). To generate 3D reconstructed images that display the course of the thoracic aorta, manual segmentation of the aortic arch and the supraaortic vessels was performed on an external workstation (Siemens Medical System) [5]. MIP reconstructions were rendered and displayed at a center level of 250 H and a window width of 1000 H.
In all 25 subjects, we performed catheter angiography under deep sedation (ketamine [Ketalar, Parke, Davis, Morris Plains, NJ], 2-4 mg/kg body weight; midazolam [Dormicum], 0.1-0.2 mg/kg body weight), using an average of 41.8 mL of nonionic contrast agent (range, 7-95 mL; average, 1.2 mL/kg body weight). Images of catheter angiography of the aorta and great vessels were obtained in the left anterior oblique and lateral projections. The average time interval between helical CT and catheter angiography was 12.5 days (range, 1-30 days). Measurement from pullback pressure recordings was obtained for each subject, and the systolic blood pressure gradients between the pre- and poststenotic segments of the former coarctation were calculated. We measured the narrowest diameter of the former coarctation and the diaphragmatic segment of the aorta perpendicular to the z-axis of the thoracic aorta on MIP reconstructions and on the catheter angiograms, using the left anterior oblique and the lateral projection images, respectively. The ratio between the narrowest diameter of the former coarctation and the descending aorta (top of the diaphragma) was calculated [2]. According to Pinzon et al. [2], the postoperative morphology of former coarctation was classified into three groups: normal contour, group A; narrowing, group B (diameter ratio, <0.75); and dilatation, group C (diameter ratio, >1.5). Linear regression was used to correlate the narrowest diameter measured on MIP images with that obtained by catheter angiography. The diameter ratio between former coarctation and descending aorta was correlated by linear regression with the systolic pullback pressure gradient of the catheter angiography. In addition, MIP reconstructions and catheter angiography were reviewed to detect circumscribed pouches, intimal flaps, and intramural calcification [2]. Pouches were classified as a circumscribed bulging of a part of the vessel's circumference, whereas intimal flaps were described as minimal tears of the inner layer of the aortic wall with the potential risk of aortic wall dissection [2]. Intramural calcification in the segment of the former coarctation as a sign of increased arteriosclerotic risk was sought with MIP reconstructions (area with increased density >130 H in the aortic wall) and catheter angiography (calcified area). The sensitivity of each method was compared (McNemar test).
Catheter angiography and MIP images were reviewed in random order by consensus of interpreters blinded to the results from the other technique.
|
TopAbstractIntroductionSubjects and MethodsResultsDiscussionReferences |
|---|
|
|
|
|
|
|
|
In addition, 3D reformatted images revealed intramural calcifications in the postoperative segment of the aorta in 10 (40%) of 25 patients (Figs. 2A,2B,3A,3B,3C,4A,4B). The mean postoperative interval in these subjects was 9.3 years; the shortest postoperative interval was 1.3 years. Mean subject age was 13.8 years; the youngest age was 1.4 years. None of these intramural calcifications were delineated on catheter angiography (McNemar test, p = 0.002). On average, segmentation and image reconstruction of the CT data sets took approximately 15 min on an external workstation. No statistically significant difference was found between both methods for the narrowest diameter in the area of former coarctation (r = 0.98) (Fig. 5) and in the descending aorta (r = 0.99) (Fig. 6). No correlation was found between the systolic pullback blood pressure gradient versus the diameter ratio of the former coarctation and the descending aorta obtained from 3D reformatted images and catheter angiograms, respectively (r = -0.04) (Fig. 7).
|
|
|
|
|
|
TopAbstractIntroductionSubjects and MethodsResultsDiscussionReferences |
|---|
The results of this study, concerning the incidence of postoperative findings (narrowing, dilatation, normal contour of the former coarctation, pouches, and flaps), correlate well with earlier published data [2]. Associated congenital cardiovascular malformations were recognized with the same frequency as those described in our study [2].
Comparing the results of MIP reconstructions and catheter angiography concerning the morphometric and morphologic parameters such as the shape of the aorta (groups A, B, and C), intimal flaps and pouches, and the diameter of the aorta (former coarctation and descending aorta) supports the suggestion by Becker et al. [5] that reconstructed CT angiography data sets of the postoperative aorta will provide clinicians with information that is comparable with diagnostic catheter angiography.
To our knowledge, intramural calcification in the former coarctation has not been described in the radiology literature until now. These calcifications identify the former coarctation as a region with increased arteriosclerotic risk. This identification allows the radiologist to focus on these calcifications as a region of possible increased risk of dissection and might be an advantage of CT angiography over MR angiography in assessment of prognosis for arteriosclerotic disease [8].
As mentioned in earlier published literature [5], associated congenital cardiovascular malformations are considered the reason for negative correlation between the postoperative morphology and the systolic pullback blood pressure gradient. Therefore, with the detection of narrowing in the 3D reconstructed images, for further treatment catheter angiography and a systolic blood pressure gradient calculation should be performed. In these subjects, MIP reconstructions may deliver helpful information for detailed planning of catheter angiography to reduce the amount of contrast media and the number of projections needed.
CT angiography with MIP reconstructions turned out to be equivalent to catheter angiography for the morphologic postoperative assessment of former coarctation. This fast simple noninvasive technique may replace diagnostic catheter angiography for the postoperative follow-up of this condition. CT angiography and MIP reconstructions were superior to catheter angiography for the detection of intramural calcifications, which identify the former coarctation as an area of increased arteriosclerotic risk. Catheter angiography should be restricted to patients with abnormal findings on CT angiography that require endovascular or operative repair.
|
TopAbstractIntroductionSubjects and MethodsResultsDiscussionReferences |
|---|
CiteULike 
Complore 
Connotea 
Del.icio.us 
Digg 
Reddit 
Technorati What's this?
This article has been cited by other articles:
|
|
 |
|
  C. Sebastia, S. Quiroga, R. Boye, M. Perez-Lafuente, E. Castella, and A. Alvarez-Castells Aortic Stenosis: Spectrum of Diseases Depicted at Multisection CT RadioGraphics, October 1, 2003; 23(90001): S79 - 91. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
L. B. Haramati, J. S. Glickstein, H. J. Issenberg, N. Haramati, and G. A. Crooke MR Imaging and CT of Vascular Anomalies and Connections in Patients with Congenital Heart Disease: Significance in Surgical Planning RadioGraphics, March 1, 2002; 22(2): 337 - 349. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. F. Corno, U. Botta, M. Hurni, M. Payot, N. Sekarski, P. Tozzi, and L. K. von Segesser Surgery for aortic coarctation: a 30 years experience Eur. J. Cardiothorac. Surg., December 1, 2001; 20(6): 1202 - 1206. [Abstract] [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
