Three-dimensional color Doppler flow reconstruction and its clinical applications

Teaching on three-dimensional presentation does not improve the understanding of according CT images: a randomized controlled study

BACKGROUND

Randomized studies have already described the advantages of three dimensional (3D) presentations in understanding complex spatial interactions. However, the clinical setting is mainly characterized by presentations of two dimensional (2D) images.

PURPOSE

This study evaluates whether training on 3D presentation enhances the understanding of 2D images.

METHODS

A teaching module was used consisting of one learning part and two examination parts (EP). Students were randomized to training with either 2D or 3D.

RESULTS

This study of 73 students showed that training on 3D presentations did not improve the ability to interpret 2D images. Further, the results revealed no significant differences between the results of Week 1 (2D: M = 6.5, SD = 1.8; 3D: M = 6.6, SD = 1.4; p > .95) and Week 2 (2D: M = 6.1, SD = 1.9; 3D: M = 6.0, SD = 1.4; p > .7). There were no significant gender differences. However, students randomized to 2D who completed only the first EP performed significantly worse if compared to students who completed both EP ( p = .04).

CONCLUSIONS

This randomized controlled study shows that correct interpretation of 2D imaging does not differ in students trained with either 3D or 2D.

Three-dimensional visualisation improves understanding of surgical liver anatomy

OBJECTIVES

Three-dimensional (3-D) representation is thought to improve understanding of complex spatial interactions and is being used more frequently in diagnostic and therapeutic procedures. It has been suggested that males benefit more than females from 3-D presentations. There have been few randomised trials to confirm these issues. We carried out a randomised trial, based on the identification of complex surgical liver anatomy, to evaluate whether 3-D presentation has a beneficial impact and if gender differences were evident.

METHODS

A computer-based teaching module (TM) was developed to test whether two-dimensional (2-D) computed tomography (CT) images or 3-D presentations result in better understanding of liver anatomy. Following a PowerPoint lecture, students were randomly selected to participate in computer-based testing which used either 2-D images presented as consecutive transversal slices, or one of two 3-D variations. In one of these the vessel tree of portal and hepatic veins was shown in one colour (3-D) and in the other the two vessel systems were coloured differently (3-Dc). Participants were asked to answer 11 medical questions concerning surgical anatomy and four questions on their subjective assessment of the TM.

RESULTS

Of the 160 Year 4 and 5 medical students (56.8% female) who participated in this prospective randomised trial, students exposed to 3-D presentation performed significantly better than those exposed to 2-D images (p < 0.001). Comparison of the number of correct answers revealed no significant differences between the 3-D and 3-Dc modalities p > 0.1). Male students gave significantly more correct answers in the 3-D and 3-Dc modalities than female students (p < 0.03). The gender difference observed in both 3-D modalities was not evident in the 2-D group (p = 0.21).

CONCLUSIONS

This study showed that 3-D imaging significantly improved the identification of complex surgical liver anatomy. Male students benefited significantly more than female students from 3-D presentations. Use of colour in 3-D presentation did not improve student performance.

Does preoperative analysis of intrahepatic venous anastomoses improve the surgeon's intraoperative decision making? Pilot data from a case report

Background

Three-dimensional (3D) visualization is thought to improve the anatomical understanding of clinicians, thus improving patient safety.

Case presentation

A 58-year-old male was admitted to our hospital in April 2007 with a suspected metastasis of a sigmoid cancer in the Couinaud segment (CS) 7. The anatomical situation of this patient was analyzed using both a CT scan and 3D images. The initial CT scan revealed that the proximal part of the middle hepatic vein was completely missing and the metastasis in the CS 7 was closely attached to the right hepatic vein. After analyzing additional 3D images, it became clear that due to the close proximity of metastasis and right hepatic vein, the resection of the right hepatic vein was inevitable. Based on this 3D analysis, it was decided to perform a right-sided hemihepatectomy. In this case report, 3D visualization resulted in a faster and clearer understanding of the unique anatomical situation in a patient with complicated liver anatomy than transversal CT images.

Conclusion

The here presented data shows for the first time 3D visualization of intravenous anastomoses in the human liver. The information offered by 3D visualization is not redundant but rather serves as a true source of additional information, indicating the potential benefit of 3D visualization in surgical operation planning.

[Three-dimensional echocardiography in cardiac surgery. Current status and perspectives]

Three-dimensional (3D) echocardiography is a new imaging technique that can provide useful information about cardiovascular morphology, pathology, and function. Recent refinements in instrumentation, data acquisition, post-processing, and computation speed allow 3D echocardiography to play an important role in cardiac imaging. These modalities provide comprehensive information on ventricular and valve morphology and function. Combined with 3D color Doppler sonography, further assessment of valvular function and determination of flow in the left ventricular outflow tract and cross-septal defects are now possible. Three-dimensional color flow imaging also makes echocardiography accurate for assessing the severity of mitral regurgitation. The purpose of this review is to describe technical developments in 3D echocardiography and its clinical application in cardiac surgery. Moreover, based on clinical studies at our centre, we describe the morphology of the mitral valve, its flow pattern, and function of the mitral annulus.

Three-dimensional versus two-dimensional transesophageal echocardiography in mitral valve repair

OBJECTIVES

We sought to compare the diagnostic performance of 3-dimensional (3D) versus 2-dimensional (2D) echocardiography in patients with regurgitant mitral valve.

BACKGROUND

An accurate assessment of morphology and function of the mitral valve is essential for surgical repair. Two-dimensional echocardiography has certain spatial limitations that could be overcome by 3D imaging.

METHODS

Preoperative transesophageal 2D and 3D studies were compared with surgical findings in patients undergoing surgical repair for severe mitral regurgitation.

RESULTS

A total of 81 consecutive patients underwent surgical repair (2002-2004). There was a high concordance (88%-100%) between both 2D and 3D studies and surgical findings in classification of involved segments. 3D imaging more accurately classified A1 segment defects (P = .05) and commissural dysfunction (P = .02). The 2D study incorrectly classified 22 segments, mainly corresponding to complex disease. The 3D study incorrectly classified 14 segments, unrelated to complex disease. Good agreement (94%, kappa 0.845) was found between non-expert and expert interpretations of 3D images.

CONCLUSIONS

Three-dimensional echocardiography offers high accuracy in mitral valve evaluation. It may complement 2D study in patients with complex valve anatomy, where surgical decisions are more difficult. The images can be easily interpreted by professionals without a high degree of experience.

Three-dimensional Echocardiography Improves the Understanding of the Mechanisms and Site of Left Atrioventricular Valve Regurgitation in Atrioventricular Septal Defect

OBJECTIVES

The purpose of this study was to determine whether 3-dimensional echocardiography (3DE) provides additional information regarding the mechanisms and sites of left atrioventricular valve regurgitation in atrioventricular septal defect compared with transesophageal 2-dimensional echocardiography (2DE).

METHODS

Eleven patients with a median age of 5.4 years (2.9-11.6 years) and a median weight of 16.8 kg (13.7-38.3 kg) with an atrioventricular septal defect underwent simultaneous transesophageal 2DE and 3DE before operation.

RESULTS

The 2DE-3DE agreement for the assessment of the superior and mural leaflet size was 72.7%. The 2DE-3DE agreement for coaptation failure, a residual or primary cleft, and commissural abnormalities as a mechanism of regurgitation were 72.7%, 63.6%, and 36.4%, respectively. For jet sites the 2DE-3DE agreement was 63.6% for a commissural and central location.

CONCLUSION

Three-dimensional echocardiography provides new and superior data regarding the mechanisms and sites of left atrioventricular valve regurgitation in atrioventricular septal defect.

Planimetric Assessment of Anatomic Valve Area Overestimates Effective Orifice Area in Bicuspid Aortic Stenosis

BACKGROUND

Although the continuity equation remains the noninvasive standard, planimetry using transesophageal echocardiography is often used to assess valve area for patients with aortic stenosis (AS). Not uncommonly, however, anatomic valve area (AVAA) obtained by planimetry overestimates continuity-derived effective valve area (AVAE) in bicuspid AS.

METHODS

Transthoracic Doppler and transesophageal echocardiography were performed to obtain AVAE and AVAA in 31 patients with bicuspid AS (age 61 +/- 11 years) and 22 patients with degenerative tricuspid AS (age 71 +/- 13 years). Aortic root and left ventricular outflow tract dimensions and the directional angle of the stenotic jet were assessed in all patients. Using these data, a computational fluid dynamics model was constructed to test the effect of these variables in determining the relationship between AVAE and AVAA.

RESULTS

For patients with tricuspid AS, the correlation between AVAA (1.15 +/- 0.36 cm2) and AVAE (1.13 +/- 0.46 cm2) was excellent (r = 0.91, P < .001, Delta = 0.02 +/- 0.21 cm2). However, AVAA was significantly larger (1.19 +/- 0.35 cm2) than AVAE (0.89 +/- 0.29 cm2) in the bicuspid AS group (r = 0.71, P < .001, Delta = 0.29 +/- 0.25 cm2). Computer simulation demonstrated that the observed discrepancy related to jet eccentricity.

CONCLUSION

For a given anatomic orifice, functional severity tends to be greater in bicuspid AS than in tricuspid AS. This appears to be primarily related to greater jet eccentricity and less pressure recovery.

Volumetric colour Doppler imaging: a useful tool for the determination of ocular blood flow in glaucoma patients?

PURPOSE

Disturbed ocular haemodynamics are discussed to contribute to the pathogenesis of glaucoma. Up to now there is no method available allowing direct determination of blood flow, which is the most relevant dimension for studies on haemodynamics. In this study, volumetric colour Doppler imaging (vCDI) is evaluated systematically in glaucoma patients.

METHODS

A Siemens Elegra ultrasound set-up with a linear 7.5 MHz probe was used for all CDI measurements. For vCDI, the cross-sectional area of a vessel and the flow velocity is determined. From both these parameters blood flow can be calculated. Ocular pulse amplitude (OPA) was assessed by the method of Langham using a pneumatic applanation tonometer.

RESULTS

(1) Velocity measurements using CDI in the ophthalmic artery and central retinal artery were highly reproducible (n=20). In contrast, reproducibility of vCDI measurements was low (n=20). Reproducibility improved if five vCDI measures were averaged. (2) Results from two different CDI-operators did not differ regarding the velocity measurements, but there was a difference in vCDI measurements (n=20). (3) Results from vCDI did not correlate with measurements of OPA in 69 patients. (4) In 15 patients, vCDI failed to detect changes of ocular perfusion induced by the application of dorzolamide.

CONCLUSION

vCDI is not applicable in ophthalmology at present.

Three-dimensional echocardiography improves the understanding of left atrioventricular valve morphology and function in atrioventricular septal defects undergoing patch augmentation

OBJECTIVES

We sought to address the role of 3-dimensional echocardiography in the evaluation of the left atrioventricular valve in children with an atrioventricular septal defect who underwent patch augmentation of their valve for either regurgitation or left ventricular outflow tract obstruction.

METHODS

Five children whose ages ranged between 4.5 and 9.2 years and who underwent patch augmentation of their left atrioventricular valve had a preoperative and postoperative transesophageal echocardiogram with 3-dimensional reconstruction to evaluate the left atrioventricular valve. The indication for operation was left atrioventricular valve regurgitation in 3 patients and left ventricular outflow tract obstruction in 2 patients. Three were rerepairs, and 2 were primary repairs. Both 3-dimensional morphology and color Doppler data were obtained. Two- and 3-dimensional findings were correlated with surgical observations through the use of direct inspection and video images obtained with a head-mounted super-VHS camera.

RESULTS

In each case there was precise correlation between the 3-dimensional and surgical findings as to the cause of leaflet failure in those with regurgitation. The site that would require leaflet augmentation could be determined by means of 3-dimensional echocardiography. Three-dimensional echocardiography provided more specific detail as to the morphology and function of the left atrioventricular valve than did its 2-dimensional counterpart.

CONCLUSIONS

Three-dimensional echocardiography provides detailed information about the status of the left atrioventricular valve in the atrioventricular septal defect and can aid in the planning of either primary or secondary repair.