Three-dimensional spiral CT venography for the pre-operative assessment of varicose patients

BACKGROUND

The purpose of pre-operative spiral CT venography or veno-CT (VCT) is to provide a precise 3D anatomic depiction of the venous network, to be used as a guideline by the surgeon.

METHODS

A multislice and multidetector spiral CT acquisition of the lower limb with diluted contrast injection produces about 400 slices in 30 s. Dedicated volume-rendering software compute interactive 3D images of the venous system. Dynamic data are easily exported by e-mail and available for phlebologists and surgeons. As VCT provides no hemodynamic data, an associated color-coded duplex is mandatory.

RESULTS

VCT is useful in case of post-operative recurrence (especially of the popliteal fossa), high or dystrophic termination of the short saphenous vein, varices feeded by the Giacomini vein, and to investigate pelvic or pudental varicose veins. A full knowledge of the complex venous networks is possible thanks to interactivity of the resulting 3D model, using rotation and modification of transparency of the tissues.

CONCLUSION

Providing a more complete anatomical information, VCT makes possible a better surgical choice of technique, avoiding anatomic pitfalls, with a more precise and limited skin approach. Accordingly, it may hopefully improve the aesthetic result as well as the efficacy, by reducing the varicose veins recurrence rate.

The origin of the azygos venous system, as deduced from an anatomical and radiological study employing a corrosion technique

The aim of this study is not only to describe the origin of the human azygos venous system by performing a 3-D reconstruction of a CT scan but also to evaluate the value of the techniques employed in investigating the topographical anatomy of a venous system in the body. Following perfusion with saline to wash away the blood, we injected an ALTUFIX/MINIUM mixture into the azygos vein of a cadaver. The head and trunk were subsequently corroded with hydrochloric acid (HCl). A CT scan of the trunk was obtained both before and after corrosion. According to the spatial resolution of the CT scan, the thinnest identifiable detail was measurable as 0.5 mm. The vertebral lumbar venous system was described, specifying the nomenclature of the lumbar veins (the lumbar veins being designated according to the vertebral body along which they run). On the right side, the lumbar veins at L2 and at L3 formed the lateral root of the azygos vein. On the left side, the vein at L2 formed the reno-azygo-lumbar arch (of Lejars). The lumbar veins, and the origin of the azygos system, were described and compared with previous studies. The 3-D reconstruction showed the importance of veins associated with the posterior paravertebral muscles. This description poses the problem of the metamerisation of the veins, but further evidence is required. Comparisons of the CT scans, 3-D reconstructions, and the ALTUFIX models of the veins obtained from the corrosion technique allowed verification of the 3-D reconstruction and correction of the errors inherent in a computer reconstruction. It is concluded that the description, and understanding, of such a complex system as the vertebral venous system is more valid when the results obtained using different techniques are compared.

[The lumbar vein at L2 and the reno-azygo-lumbar arch: anatomic and radiologic studies]

The lumbar vein at L2 was described by C. Gillot and B. Singer (1974). On the right side, after drawing off the 12th intercostal vein, it forms the lateral root of the azygos vein. Its way is as a frame, transverse going along the body of the 2nd lumbar vertebra, then upward along the spine after having integrated the veins of the L2-L3 intervertebral foramen. In its typical form, the vein is at L2 but it can be at L1 or L3. It takes the name of lateral root of the azygos vein only after receiving the 12th intercostal vein. Because of its diameter (5 mm), it forms a cavo-caval anastomosis via the azygos vein. The renal azygo-lumbar arch of Lejars is the equivalent on the left side of the right vein at L2. This arch contributes to the formation of the lateral root of the hemi-azygos vein. The right vein at L2 and the reno-azygo-lumbar arch were studied by dissections and by radiologic protocols. The radiologic studies (CT, MRI, 3D reconstructions) were carried out after injections of gelatin-gadolinium-minimum and altufix-minimum mixtures. The results showed the numerous variations of origin of the azygos system. The use of multiple and complementary technics are very helpful to describe these variations.

[Value of the spiral angio-scanner with three-dimensional reconstruction in the surgical strategy of unifocalization. Apropos of a case]

One of the difficulties of surgical treatment of pulmonary atresia with patent septum by unifocalisation resides in the accurate diagnosis of the different collateral vessels to the lung in order to optimise the surgical approach: anterior or posterolateral thoracotomy, and to determine the type of operation: one or two stages repair. Conventional angiography, even using different views, cannot always give an accurate representation of the anatomy of the different collateral vessels, especially their relationship to the bronchial structures. The authors report the contribution of spiral angioscanner with three dimensional reconstruction in the determination of the operative strategy of a case of pulmonary atresia with patent septum.

Catheter fragments embolization

Although the use of central venous silicone catheters is widespread, little is known about the incidence of catheter rupture and embolization. Over a three-year period, 3916 silicone catheters were inserted in 3672 patients in the authors' hospital. Catheter or catheter fragments embolism occurred in 4 patients (1.2 embolizations per 1000 patients treated). Inappropriate mechanical deobstruction attempts resulted in 2 embolizations, and hence, these should be avoided. Chest roentgenography failed to detect the small fragments within the heart silhouette in 2 cases. Two-dimensional echocardiography showed the separated catheter fragment in all 4 cases. All four catheter fragments were subsequently removed from the right-heart chambers.

Anatomic study of the lumbar region applied to multiplanar imaging techniques: importance and use of oblique vertical sections

This anatomic study of the lumbar region (as defined by Rouvière [11]) applied to multiplanar imaging techniques was carried out both in the cadaver and in vivo. The cadaver study (5 cases) consisted of anatomic sections (transverse, sagittal, frontal and oblique) and computerised three-dimensional reconstructions after CT studies on subjects injected with colored and radio-opaque latex. The in vivo study (4 cases) used MRI sections and three-dimensional ultrasound sections coupled with the pulsed doppler. The spatially referenced oblique vertical sections revealed the structures from unusual aspects, situating them amidst the retroperitoneal area with the maximum of topographic landmarks. The transposition of these results (obtained by sectional anatomy of the retroperitoneal region) to the new techniques of multiplanar formatting after MRI, ultrasound or CT data acquisition should optimise the investigation of certain retroperitoneal structures by specifying the ideal planes of section for each organ, while diminishing certain artefacts specific to acquisitions in the traditional planes of section. Oblique vertical sections seem eminently suitable for ultrasound location of the suprarenal compartments, study of the renal pedicles and topographic retroperitoneal location. This oblique vertical visualisation constitutes a fundamental resource for the development of video-monitored surgical procedures as it corresponds exactly to the axes of the access routes in percutaneous surgery of the kidney and the adjacent anatomic structures.

Variations in arterial blood supply and the risk of hemorrhage during percutaneous treatment of lesions of the pelviureteral junction obstruction: report of a case of testicular artery arising from an inferior polar renal artery

Acute hemorrhage during percutaneous surgery on the pelviureteric junction obstruction has been estimated to be 2-3%. Following the experience of peroperative bleeding from a vascular variation, the authors discuss the arterial anomalies of the renal pedicle which may carry the risk of hemorrhage during percutaneous surgery in this region. Arteries in front of or behind the renal pelvis are the cause of ureteropelvic function obstruction in 15-52% of cases and because of their close relationship with the upper urinary tract can complicate the procedure of endopyelotomy. Endourological techniques are inadequate for avoiding the risk of vascular damage during the necessary maneuvers. Inferior polar arteries occur in 9% of the population and their different courses are described. They are not always responsible for the vascular obstruction in the pelviureteric syndrome, and it is the exact determination of this responsibility that makes imaging essential. Arteriography performed in our case allowed embolisation of the damaged inferior polar artery and also showed the anomalous origin of the testicular artery from this polar artery; this appears to be only the second description of this anomaly. This variation is discussed in a review of the literature. In fact the testicular artery has a high or aberrant origin in 20% of cases; in 5-6% of these the origin is from a main or supernumerary renal artery. Origin from an inferior polar artery is exceptional.

Criteria for anatomical compatibility of the total artificial heart: computerized three-dimensional modeling of the cardiovascular anatomy

A quantitative study of cardiovascular anatomy was performed by obtaining three-dimensional reconstructions from regular computed tomography scan images in 15 patients, all candidates for heart transplantation. Volumetric estimates of the cardiovascular structures were obtained from these three-dimensional reconstructions using data directly related to total artificial heart (TAH) implantations. By using computerized three-dimensional modeling of these structures, reproducible measurements of the parameters defining the shape and the anatomical connections of the intrathoracic space available for TAH implantation could be derived. The results are intended to be used for both technical and clinical applications such as computer-assisted drawing of the pericardial cavity and the anatomical connections (useful for improving the design of TAH) and combined statistical calculations (multiple regressions, cluster algorithm) of the measurement results, which will then enable the best selection to be made among two or three TAH models for each patient.

Three-dimensional modeling of the anatomy of the heart and great vessels

The anatomic constraints imposed on a total artificial heart (TAH) require specific anatomic studies. A thoracic anatomic study was performed with a scanning device equipped with three-dimensional (3-D) reconstruction software on 15 male patients, between the ages of 41 to 63 years (52 +/- 6 years). All were candidates for heart transplantation. The 3-D reconstructions of the cardiovascular structures obtained from surgical anatomy data specific to TAH implantation allowed a volumetric measurement of these structures. A modeling diagram of these structures permitted reproducible quantitative measurements of the 35 geometrical parameters which characterized shape, orientation, and position of these structures within the thorax. Most of the measured parameters were characterized by low variability (coefficient of variation from 10 to 25%).

Modifications of the skull base in artificial deformations of the circumference of the head

Four artificial deformations of the skull (collection of the Laboratoire d'Anthropologie of the Musée de l'Homme) have been analysed in terms of their morphology and osteometry. The study of the endocranial base in the three planes of space was made possible by a computerised three-dimensional reconstruction based on data gathered by CT. These four skulls were paired as regards their shape (2 annular and dolichocephalic and 2 tabular and brachycephalic) and as regards their age (2 skulls of children and 2 of adults). Certain modifications of the base, such as a tendency to platybasia and to an antero-superior tilt of the posterior fossa around an axis passing through the basion, could be observed in the two modalities of deformation studied. The existence of a region little subject to modelling combining the body of the sphenoid and the basilar and lateral portions of the occiput was confirmed as regards the chondrocranium, whereas the peripheral structures of the base were remodelled like the membranous structures of the vault of the neurocranium.

[Three-dimensional CT study of the carpus under pronation-supination constraints]

By studying 3D imaging of the wrist under pronation-supination strain, we found that the simple comparison of a series of two corresponding cuts may provide a great deal of useful information on how the carpus transmits the longitudinal torque from the forearm to the hand. A special wooden trestle was made to fix the subject in the CT scanner in a permanent effort of pronation or supination. In the first group of scans, this effort was said to be "free" because the hand was simply maintained in a fixed window without any muscular contraction, except pronation or supination muscles. In the second group of scans, this effort was said to be "constrained" because the hand gripped a fixed bar with contraction of the flexor muscles. The thickness of the cuts was 1.2 millimeters and they were separated by 1.5 millimeters. Four levels were specially studied: the lower radio-ulnar joint (LRUJ), the proximal row of the carpus, the distal one and the metacarpal bases. Many elementary movements occur in the carpus in constrained supination: the triquetrum "supinates" (7 degrees), the scaphoid flattens and "pronates" (2 degrees) around the capitum the ridges of the carpal anterior concavity approximate (3 mm). In constrained pronation, the anterior concavity of the carpus flattens emphasizing the role of the anterior retinaculum. The LRUJ is very unstable: in free pronation, the ulnar head moves dorsally, firmly pressing the posterior part of the sigmoid notch, responsible for fracture of a postero-medial fragment in Colles fracture. The quadratus pronatus is a very important muscle to coapt this joint. We propose the "screwing (or unscrewing) test" in the diagnosis of arthrosis or instability of the LRUJ. We define the notion of "rotational shift" to appreciate the quality of the pronation/supination torque transmission. In constrained pronation/supination, this rotational shift is 5 degrees in the radio-carpal joint. This is very important to appreciate the quality of the wrist prosthesis. In free pronation/supination, the rotational shift is 45 degrees between radius and metacarpal bases. In constrained pronation/supination, it becomes 10 degrees. The wrist ligaments are unable to resist the wrist rotational shift and favor the torque transmission. The tendinous caging of the wrist is the main factor for maintaining rigidity of the carpus and transmitting the torque as muscles are contracted. The wrist can be compared with a fluid drive clutch, whose pedal is muscular contraction.

[Retro-aortic left brachiocephalic venous trunk. A rare anomaly: 2 cases]

Two cases of a rare anomaly of the trajectory of the left brachiocephalic venous trunk were detected by CT scan imaging. In both patients the trunk passed under the aortic arch before emptying into the superior vena cava. One patient presented, in addition, a complex anomaly of the aortic arch.

[Value and limitations of puncture guided by x-ray computed tomography in hematology]

Interpretable cytologic data were obtained in 63% of a series of 68 punctures, for biopsy of hematologic affections, guided by CT scanning. The frequency of puncture of post-therapy residual masses (44 cases) explains the high incidence of non-significant examination results after lymph node puncture. The technique was most effective (78% of punctures exploitable) when used for thoracic masses and visceral localizations. The method is very safe: lack of serious incidents and minor reactions, mainly during thoracic puncture, in only 4.4%. The method is simple in use and should be employed, within certain limits that should be recognized, very widely in hematologic diseases.