Expandable tubular stents for treatment of arterial occlusive diseases: experimental and clinical results. Work in progress

The balloon-expandable vascular prosthesis consists of a flexible, knitted tantalum wire mesh tube. To demonstrate its pliability, this prosthesis was tested experimentally in 10 mongrel dogs by implanting it into the proximal femoral arteries. The maximum follow-up time was 1 year. On the basis of the experimental results, in which there was no relevant stenosis, occlusion, or migration of the vascular prosthesis, nine patients were treated: one with iliac artery occlusive disease and eight with superficial femoral artery (SFA) occlusive disease (four reocclusions after angioplasty and four unsatisfactory primary angioplasty results). One SFA lesion was treated with the crossover method from the contralateral side. All implants remained patent without hemodynamically significant stenoses, with the longest observation time being 6 months. Flexible, expandable vascular prostheses are promising adjuncts to angioplasty.     

Automated breast sonography using a 7.5-MHz PVDF transducer: preliminary clinical evaluation. Work in progress

Breast ultrasound imaging performed with an automated machine was carried out in 89 patients, and images obtained with a conventional ceramic single-focus 4-MHz transducer and a 7.5-MHz polyvinylidene fluoride (PVDF) transducer were compared. The 7.5-MHz PVDF transducer improved overall image quality in 77% of patients and had equal penetration in 83%. It yielded greatly increased diagnostic information in 43% of 81 masses and improved visualization of calcification in 57% of 14 lesions in which calcium was visible on mammograms.     

冠状动脉搭桥术后磁共振桥血管成像的初步探讨

目的 以ＭＲ成像评价桥血管开通及功能,探讨适用于国人冠状动脉搭桥（ＣＡＢＧ）术后的影像学随访手段,方法 用１．５ＴＭＲ机检查２７例ＣＡＢＧ术后患者的７４支桥血管,行屏气快速场回波（ＦＦＥ）序列扫描观察桥血管的开通。其中１６例４２支桥血管行相位对比磁共振血流成像（ＰＳＭＲＡｆｌｏｗ）,得出血流速度和流量曲线,对桥血管的开通进行再评价。结果 本组桥血管ＦＦＥ成像开通率为８９．２％（６６／７４）。以ＰＳ     

Ovarian cysts in postmenopausal women: preliminary results with transvaginal alcohol sclerosis. Work in progress.

Seven patients with a recurrent ovarian cyst after transvaginal needle aspiration underwent alcohol sclerosis of the cyst. The cysts had the appearance of simple cysts at ultrasound (US). Sclerosis, an outpatient procedure, was performed with a transvaginal approach under continuous endovaginal US guidance. After aspiration of the cyst contents, approximately two-thirds of the aspirated fluid was replaced with 100% alcohol that was left in place for 20 minutes and then aspirated. No complication was observed. Four cysts had not recurred at follow-up examinations performed 2, 5, 7, and 12 months, respectively, after sclerosis. One patient underwent surgery because mucinous material was found on analysis of the specimen, which was proved to be a benign cystadenoma. The two other cysts recurred, and one patient underwent surgery. Alcohol sclerosis of ovarian cysts may have a role in the treatment of postmenopausal women with ovarian cysts with a low risk of malignancy.     

Expandable metallic biliary endoprostheses: preliminary clinical evaluation

A biliary endoprosthesis constructed of self-expanding metallic "Z" stents was placed in 23 patients with obstructive jaundice. The biliary obstruction was due to a malignant neoplasm in 21 patients and a postoperative biliary stricture in two patients. The lesions affected the intrahepatic biliary ducts in 13 patients. Twelve patients had undergone radiation therapy before stent placement. The endoprostheses consisted of 196 expandable metallic biliary stents placed singly (n = 10) or in tandem (n = 186). As many as 18 stents were used to relieve an obstruction in one patient. A transhepatic approach was employed in all patients except one in whom stents were placed through a T-tube tract. Within 1 week after placement, all stents expanded to at least 90% of their original diameter. Three misplaced, two deformed, and two dislodged stents caused no obvious clinical problems. At follow-up, which ranged from 2 to 59 weeks, five patients experienced recurrent jaundice. Two patients with recurrent jaundice due to obstruction of the bile duct containing the stent were treated with external catheter drainage. The expandable biliary endoprosthesis is suggested as an effective treatment for benign and malignant biliary obstruction.     

Fetal imaging by nuclear magnetic resonance: a study in goats. Work in progress

Nuclear magnetic resonance proton imaging was used to obtain images of goat fetuses in utero. The long T1 relaxation time of amniotic fluid makes it appear black on proton density images when examined using the Aberdeen imager, and so allows very good discrimination of the position and structure of the fetus. Some fetal internal tissues can be seen on T1 images. These findings suggest that NMR imaging has great potential in pregnancy studies.     

The AFL penetrometer study: Work in progress

Five hundred and seventy one matches in the Australian Football League [AFL] had ground hardness measured using a Penetrometer, over the period 1997-2000. The method used was 3 drops at each of 20 locations over the playing field on the morning before games. Anterior Cruciate Ligament [ACL] injuries were recorded using an ongoing injury surveillance system. There was a non-significant trend towards a higher risk of ACL injury when the 3-drop average of the Penetrometer was less (harder) than 4.5cm, RR 2.36 (95% CI 0.90-6.24). When the first drop average of the Penetrometer was less (harder) than 2.5cm, the relative risk was 2.60 (95% CI 0.94-7.20). There was also a nonsignificant trend towards an increased risk of ACL injury in games where the predominant grass type was couch (Bermuda) grass, as opposed to rye grass, RR 2.37 (95% CI 0.89-6.36). This study confirms previous findings from the AFL that early season matches and matches played at northern (warmer) venues have a higher risk of ACL injury. It is likely that ground-related variables are partially responsible for these observations, but to date, the relative contributions of ground hardness, grass type, shoe-surface traction and other confounding factors are not certain. There was a significant fall in the number of ACL injuries in the AFL (to approximately half the previous level of incidence) during seasons 1999 and 2000. It is possible that reaction to this study and related publicity has led to the preparation of ground conditions in the AFL that are less likely to produce ACL injuries.     

Treatment of autonomous thyroid nodules with percutaneous ethanol injection: preliminary results. Work in progress

Eight patients with autonomous thyroid nodules 2.4-4.3 cm in diameter received percutaneous ethanol injections (PEIs) under guidance by means of ultrasound (US). Sterile ethanol at 95% was injected with a 22-gauge needle and a 7.5-MHz probe with a guide device. Each patient received one or two treatments, with 1-3 mL of alcohol (depending on the nodule size) per treatment, each week for a total of three to six injections per lesion. After a total of 36 injections in all eight patients, there were no complications. Follow-up ranged from 2 to 10 months. After therapy, symptoms subsided and hormonal levels became normal or reached the range of subclinical hypothyroidism. Scintigrams showed that the previously suppressed thyroid tissue had resumed functioning. At US, all nodules had shrunk. PEI was risk free and easy to perform. If these preliminary results are confirmed in a larger study with longer follow-up, the new treatment may become an alternative to surgical or radioiodine ablation of autonomous thyroid nodules.     

Percutaneous placement of a balloon-expandable intraluminal graft for life-threatening subclavian arterial hemorrhage.

A balloon-expandable intraluminal graft was percutaneously deployed in the left subclavian artery of a 43-year-old woman. This graft was made of a stainless steel, 30-mm Palmaz balloon-expandable iliac stent completely covered with a thin coat of silicone. The procedure was successful in managing and preventing life-threatening hemorrhage as a large-bore catheter was removed from the subclavian artery via its subcutaneous tunnel. Surgical repair of the high brachial-axillary sheath insertion site was required after percutaneous deployment of the graft. However, the grafting procedure succeeded in obviating a thoracotomy. At follow-up of 6 months, despite diminution in brachial pulse volume recordings, the patient is asymptomatic at rest. She experiences mild fatigue with extremes of upper extremity exercise and declines angiographic follow-up and further intervention.     

Urokinase-mediated thrombolysis: a dose-response relationship in cats. Work in progress.

A cat model was developed to study thrombolytic agents. The infrarenal aorta was surgically exposed, all side branches were ligated, and both ends of the segment were occluded. After preformed clot was injected into the segment, proximal flow was restored and a distal stenosis was created. Urokinase was infused at rates varying from 4,000 to 250,000 U/h. Amount of remaining clot was quantified every 15 minutes with cine angiography. Pre- and postinfusion measurements of prothrombin time, partial thromboplastin time, thrombin time, and levels of fibrinogen and fibrin degradation products were obtained. A graph of thrombolysis rate versus infusion rate was obtained yielding maximal thrombolytic activity at 126,000 U/h and 90% of maximal activity at an infusion rate of 70,000 U/h. Levels of fibrin degradation products did not change. Prothrombin, partial thromboplastin, and thrombin times increased with increasing infusion rates, leveling off at 100,000 U/h, while fibrinogen levels decreased, with a plateau at 50,000 U/h.     

Pulmonary asbestosis: CT study of subpleural curvilinear shadow. Work in progress

High-resolution computed tomographic scans of 19 patients with pulmonary asbestosis revealed a subpleural curvilinear shadow (SCLS) parallel to the inner chest wall in the lungs of 15 (78.9%) patients. Most (46.7%) SCLS measured greater than 5 cm but less than 10 cm in length and occurred less than 1 cm from the inner chest wall in all cases. SCLS was distributed mainly in the lower lobe in patients with mild pulmonary fibrosis and in segments where fibrosis was mild in patients with honeycomb shadows. This may reflect initiation of pulmonary fibrosis leading to the formation of a honeycomb shadow. Radiologic-pathologic correlation, achieved in one postmortem specimen, seemed to indicate that SCLS was associated with the initial change of fibrosing bronchioloalveolitis, which is characteristic of pulmonary asbestosis.     

Angioscopy of the inferior vena cava: preliminary observations in cases with involvement by neoplasm. Work in progress.

Angioscopy of the inferior vena cava (IVC) was performed in 10 patients. Tumor thrombus extending into the IVC was suspected in six patients, and direct invasion of the IVC wall was suspected in four, based on computed tomographic and venographic findings. In each case, a fiberscope was directed to the area of interest in the IVC via a transfemoral 5-F catheter. Blood displacement by means of a saline infusion enabled angioscopic observation of the IVC wall. The neoplasms were seen clearly in all patients but one. The color and texture of the tumor thrombi surface made it easy to distinguish from the healthy IVC wall. In the four patients believed to have direct invasion of the wall, there were no angioscopic differences between the suggestive areas and adjacent areas of normal IVC wall. In these four cases, the absence of direct invasion was confirmed at surgery. Thus, angioscopy helps make an accurate nonoperative or preoperative diagnosis of tumor thrombi possible and may aid in the exclusion of direct invasion.     

Vena caval filter to prevent pulmonary embolism: experimental study. Work in progress

A new inferior vena caval filter was tested in an experimental series of 23 dogs and in an in vitro study. The filter consists of a pliable basket and anchoring legs made of stainless steel. It can be inserted percutaneously in an antegrade or retrograde fashion through a 10-F Teflon catheter and can be retrieved with a snare or forceps. The filter is self-orienting in the inferior vena cava, becomes securely the inferior vena cava, becomes securely fixed to the wall, and has exhibited no tendency to migrate. It is highly effective in capturing small and large emboli. There was no significant elevation in upstream hydrostatic pressure following entrapment of emboli. Spontaneous thrombus formation within the basket was observed in two of six dogs who had short-term follow-up. In dogs who had long-term follow-up, the filter remained patent. Microscopically, the filter caused sclerosis of the intima where the wire was in contact with the vessel wall. Breakage of an anchor leg and separation at the fusion between anchor and basket were seen in the study. They were eliminated by improvement of the prototype, which is now ready for clinical application.     

Prostatic hyperplasia: radiological intervention. Work in progress

Benign prostatic hypertrophy is the most common cause for urethral obstruction in males over 50 years of age. Interventional radiologic dilatation under fluoroscopic control offers a nonoperative alternative for treatment of prostatic hyperplasia. Cadaver studies with the use of arteriographic balloon catheters indicated that manual injection pressure provides effective dilatation of the prostatic urethra. Evaluation of symptom relief will have to await patient studies.     

Osteomyelitis: detection with US. Work in progress

Ten patients with clinically suspected osteomyelitis were studied with ultrasound (US). Five patients had abnormalities detectable on sonograms. An abnormal fluid collection was demonstrated adjacent to the bone in three of these five. US-guided aspiration of the fluid in two of the three patients revealed purulent or infected fluid that was thought to represent an inflammatory exudate dissecting in a subperiosteal or extraperiosteal location. Findings from subsequent radiographic and scintigraphic studies confirmed the diagnosis of osteomyelitis in these three patients. The other two patients with abnormal sonographic results had collections of fluid that were separated from the bone by a variable amount of soft tissue. These collections were confined to the soft tissue and did not appear to arise from the bone. Aspiration revealed a soft-tissue abscess in one patient and a seroma in the second. Findings in this preliminary study suggest that fluid around the bone seen on sonograms may indicate acute osteomyelitis.     

Carotid bifurcation: MR imaging. Work in progress

To devise and implement an in-plane magnetic resonance angiography examination of the carotid bifurcation capable of producing high-resolution images, the authors examined 19 normal carotid arteries and 14 patients with angiographically documented disease with two flow-correction techniques: a three-gradient, velocity-refocused technique with spin-echo (SE) and gradient-echo sequences, and a four-gradient velocity- and acceleration-corrected SE technique. With use of three equal gradients in the read direction, velocity-related phase changes were minimized by placing the dephasing gradient after the 180 degree pulse and near the read gradient. Acceleration effects were minimized through the use of short echo times and cardiac gating. Both velocity- and acceleration-produced phase changes were corrected with the four-gradient scheme but at the expense of some limitations in spatial resolution. Both techniques consistently produced satisfactory images of the carotid bifurcation in healthy individuals. However, the results indicate that the present gradient-phase modulation techniques have several drawbacks, including susceptibility to patient motion, overlapping with the jugular vein, and inability to image carotid stenosis accurately due to turbulence.     

Percutaneous angioscopy. Work in progress

The cardiovascular applications of flexible fiber-optic technology are imminent because of recent advances in miniaturization. In the work described here, angioscopy, or vascular endoscopy, was performed in the cadaveric aorta and in the systemic and pulmonary circulations of the canine model and selected human patients. Subsequent to our development of percutaneous techniques, clinical trials have ranged from lower-extremity venoscopy to aortic-root arterioscopy. Angioscopy could be clinically useful because of relative or absolute contraindications to iodinated contrast material. The ability to see in color and three dimensions may afford some other advantages to angioscopy over conventional angiography.