Three-dimensional computed tomography studies of the tendons of the foot and ankle

Application of Computed Tomography Processed by Picture Archiving and Communication Systems in the Diagnosis of Acute Achilles Tendon Rupture

The applications of CT examination in the diagnosis of the acute Achilles tendon rupture (AATR) were investigated. A total of 36 patients with suspected acute Achilles tendon rupture were tested using physical examination, ultrasound, and 3DCT scanning, respectively. Then, surgery was performed for the patients who showed positive result in at least two of the three tests for AATR. 3DVR, MPR, and the other CT scan image processing and diagnosis were conducted in PACS (picture archiving and communication system). PACS was also used to measure the length of distal broken ends of the Achilles tendon (AT) to tendon calcaneal insertion. Our study indicated that CT has the highest accuracy in diagnosis of acute Achilles tendon complete rupture. The length measurement is matched between PACS and those actually measured in operation. CT not only demonstrates more details directly in three dimensions especially with the rupture involved calcaneal insertion flap but also locates the rupture region for percutaneous suture by measuring the length of distal stump in PACS without the effect of the position of ankle. The accuracy of CT diagnosis for Achilles tendon partial rupture is yet to be studied.

Three-dimensional volume rendering of the ankle based on magnetic resonance images enables the generation of images comparable to real anatomy

We have applied high-quality medical imaging techniques to study the structure of the human ankle. Direct volume rendering, using specific algorithms, transforms conventional two-dimensional (2D) magnetic resonance image (MRI) series into 3D volume datasets. This tool allows high-definition visualization of single or multiple structures for diagnostic, research, and teaching purposes. No other image reformatting technique so accurately highlights each anatomic relationship and preserves soft tissue definition. Here, we used this method to study the structure of the human ankle to analyze tendon-bone-muscle relationships. We compared ankle MRI and computerized tomography (CT) images from 17 healthy volunteers, aged 18-30 years (mean 23 years). An additional subject had a partial rupture of the Achilles tendon. The MRI images demonstrated superiority in overall quality of detail compared to the CT images. The MRI series accurately rendered soft tissue and bone in simultaneous image acquisition, whereas CT required several window-reformatting algorithms, with loss of image data quality. We obtained high-quality digital images of the human ankle that were sufficiently accurate for surgical and clinical intervention planning, as well as for teaching human anatomy. Our approach demonstrates that complex anatomical structures such as the ankle, which is rich in articular facets and ligaments, can be easily studied non-invasively using MRI data.

Predictive value of preoperative 3-dimensional computer tomography measurement of semitendinosus tendon harvested for anterior cruciate ligament reconstruction

PURPOSE

The aim of this study was to evaluate preoperative measurement of the semitendinosus tendon (ST) by 3-dimensional computed tomography (3-D CT), before using ST as the substitute in the anterior cruciate ligament (ACL) reconstruction.

TYPE OF STUDY

Cross-sectional study to compare anatomic findings with clinical findings.

METHODS

The study involved 28 patients who underwent ACL reconstruction using autogenous ST graft. Preoperative 3-D CT images of ST were obtained with a multidetector-row CT scanner, and rendered qualitatively by the volume-rendering technique. The length and cross-sectional area of ST measured with 3-D CT were compared with the length of the harvested ST and the cross-sectional area of the grafted quadrupled tendon.

RESULTS

The total length of ST measured with 3-D CT ranged from 220.3 to 285.4 mm, with a mean (+/- SD) of 248.0 +/- 17.1 mm, and that measured at surgery ranged from 230.0 to 290.0 mm, with a mean of 257.1 +/- 16.5 mm. These 2 values showed a close positive correlation (gamma = 0.634, P = .002). The cross-sectional area of ST measured with 3-D CT ranged from 4.29 to 18.5 mm2 with a mean of 11.9 +/- 4.6 mm2, and that of the substitute measured at surgery ranged from 28.3 to 56.7 mm2 with a mean of 45.5 +/- 6.9 mm2). There was no significant correlation between the areas of ST measured by CT and the areas of ST measured during surgery.

CONCLUSIONS

Preoperative 3-D CT imaging predicts the length of ST. These findings support the measurement of ST length by 3-D CT as a useful tool for planning ACL reconstructive surgery and for providing important preoperative information to patients.

LEVEL OF EVIDENCE

Level III, diagnostic study.

Three-dimensional CT imaging of flexor tendon ruptures in the hand and wrist

OBJECTIVE

The purpose of this study is to determine the applicability of 3D CT imaging in the evaluation of flexor tendon rupture in the hand and wrist.

DESIGN

Twenty-four digits in 22 patients (18 adults, 4 children) with a spectrum of finger flexion disturbances were investigated by a multidetector-row CT scanner, and diagnosed by 3D CT image with the volume rendering technique. The accuracy of the image diagnosis was confirmed operatively in 20 digits.

RESULTS

3D CT imaging gave a precise analysis in all adult cases. It clearly depicted the location of rupture and tendon stump. All of the 12 digits diagnosed from the images as tendon rupture were operated on, and the operational finding correlated well with the diagnosis based on the image. In the children, the image analysis was equivocal.

CONCLUSIONS

3D CT imaging can be useful when the diagnosis of flexor tendon rupture cannot be made based on trauma history and clinical examinations, and can be helpful in surgical planning.

Volume rendering of tendon-bone relationships using unenhanced CT

OBJECTIVE

Clinically, three-dimensional CT of the extremities is most often used to display bony anatomy. However, by combining unenhanced CT with volume-rendering computer graphics, visualization of relationships between bone and soft-tissue structures such as muscle tendon is also possible. The aims of this study were to quantify CT attenuation values of peripheral tendon, muscle, and bone on unenhanced CT and to develop custom opacity transforms on the basis of the attenuation measurements to effectively depict tendon-muscle-bone relationships.

CONCLUSION

The mean attenuation of peripheral tendon ( approximately 100 H) is distinctly higher than that of muscle ( approximately 60 H) enabling high-quality volume rendering of muscle-tendon-bone relationships with unenhanced CT. High-frequency (bone) CT reconstruction algorithms commonly used for extremity CT produce approximately twofold higher image noise and inferior three-dimensional renderings compared with those based on less noisy standard or soft-tissue reconstruction algorithms. These concepts can be used to uniquely reveal tendon-muscle-bone relationships for clinical, scientific, and educational purposes.

3D display: a survey from theory to applications

We survey some of the literature on three-dimensional medical imaging. We report both on technical developments and on medical applications, with a concentration on material that has been published within the years 1990-1992.