Feasibility of MRI in the diagnosis of acute diverticulitis: initial results

PURPOSE

The purpose of this study was to evaluate MRI as a diagnostic tool in patients with suspected acute sigmoid diverticulitis. Furthermore, we sought to develop an optimal imaging protocol in these patients.

PATIENTS AND METHODS

Eleven patients with suspected acute diverticulitis were included in the study. All patients were imaged in a 1.0 T clinical scanner using a body-array coil. Imaging sequences were single-shot TSE, HASTE-, STIR- and TrueFisp- sequence. All were obtained in the frontal plane. The diagnosis was verified by a single experienced investigator, using ultrasound, and overall clinicopathological outcome.

RESULTS

MRI enabled visualization of signs of an acute diverticulitis in all patients. However, the diagnosis of acute diverticulitis was obtained in 10 patients only. The mean imaging time was 17.5+/-5.5 min. STIR- and TrueFisp-sequences alone displayed all findings, e.g pericolonic exsudation, edema and segmental narrowing, whereas SSTSE and HASTE-sequences showed no additional information. Therefore, it appeared that the imaging protocol could be restricted to STIR- and TrueFisp-sequences.

CONCLUSION

MRI is feasible as a fast, accurate and investigator-independent diagnostic tool in patients with suspected acute diverticulitis. To prove its value in comparison to computed tomography or ultrasound, further studies are needed.

MRI versus arthroscopy in the diagnosis of scapholunate ligament injury

In a prospective study 103 patients with clinically or radiologically suspected tears of the scapholunate interosseous ligament were investigated with magnetic resonance imaging (MRI) and wrist arthroscopy. MRI was performed with the conventional technique in 72 cases and after intravenous injection of contrast medium in the remaining 31 patients. The correct diagnosis was made by MRI in 75% of cases and its overall sensitivity and specificity were 63% and 86% respectively. There was no statistical difference in the accuracy of MRI for acute or chronic tears and the use of intravenous contrast medium did not improve its accuracy. In conclusion, MRI is not recommended for the diagnosis of scapholunate ligament injury.

In vivo evaluation of an intravascular receiver coil for MRI at 1.0 Tesla

BACKGROUND

Evaluation of the applicability of intravascular radiofrequency receiver coils by means of a pig in-vivo-experiment for the detection of vessel wall structures at 1.0 Tesla.

MATERIALS AND METHODS

The intravascular receiver coil was constructed according to a well evaluated single-loop-design, which was mounted onto a balloon catheter for angioplasty. Under fluoroscopy control the balloon catheter was placed in the common carotid artery of a porcine. Images were obtained in a 1.0 Tesla clinical scanner using a fast-spin-echo-, a gradient-echo- and a high resolution spin-echo-sequence. Histological examinations were obtained to detect any vessel wall damage associated with the use of the receiver coil.

RESULTS

High quality images with a resolution up to 0.16*0.12 mm2 could be acquired in aquisition times of about 5 minutes. Subtle intra- and extra-vascular structures such as the balloon, irregularities of the vessel wall or bordering structures could be visualized. The histological examination showed no vessel damage due to the application of the intravascular receiver coil.

CONCLUSIONS

The application of intravascular receiver coils for the visualization of the vessel wall is feasible at 1.0 Tesla without histologically detectable trauma to the vessel wall.

Standardisation of imaging in neuroendocrine tumours: results of a European delphi process

In 1998 and 1999, a delphi consensus procedure was performed to establish guidelines for standardised diagnostic imaging of neuroendocrine tumours. The procedure included four consecutive workshops of a European group of experts in neuroendocrine tumours as well as feedback given by specialists from the departments of radiology, nuclear medicine, surgery and internal medicine of the according home institutions. Diverging approaches among the centres, which became apparent during the discussion, reflect a lack of controlled studies specifically for rare subgroups of neuroendocrine tumours. This paper summarises the standards for diagnostic imaging as developed during the delphi process. In particular, the diagnostic workflows as well as the technical properties of different imaging modalities are described in detail.

MR hydrometry to assess exocrine function of the pancreas: initial results of noninvasive quantification of secretion

PURPOSE

To evaluate magnetic resonance (MR) hydrometry, a method of quantifying fluid amounts by using MR imaging, for assessing the exocrine function of the pancreas after stimulation with secretin.

MATERIALS AND METHODS

Images were obtained with a single-shot turbo spin-echo sequence by using a 1.0-T magnet with a quadrature body coil. Image postprocessing and evaluation were performed at an external workstation by using a specially designed histogram algorithm that translates the MR signal intensity of duodenal filling into an actual amount of duodenal fluid. This algorithm was tested in vitro and in vivo. Finally, MR hydrometry results in five patients were correlated with those of the secretin-cerulein test.

RESULTS

The phantom measurements showed a high correlation (r = 0.99) between the actual amount of fluid in the imaging volume and the calculated results. In vivo, the ability of MR hydrometry to enable exact quantification of fluid amounts was demonstrated. In correlating the signal intensity of duodenal filling with the exact amount of additional fluid in the duodenum in volunteers, a coefficient of 0.043 gray tones per pixel per milliliter was calculated. The correlation (r) between secretin-stimulated duodenal fluid output estimated by using tube aspiration and that estimated by using MR hydrometry was 0.946 (P <.05).

CONCLUSION

MR hydrometry is a promising noninvasive method of assessing fluid output as a measure of exocrine pancreatic function.

[A review of molecular radiology. I: Gene therapy]

The term molecular radiology intermediate region between radiological imaging and interventional radiology on the one side and molecular biology on the other. In the field of imaging methods are currently being developed by which molecular processes, i.e., gene expression and protein function, can be visualized in vivo. These techniques open new perspectives for research and clinical diagnosis and will be presented in the second part of this review. The present part provides a survey of current developments in gene therapy from a radiological point of view and highlights the part that our specialty may play in this field.

Feasibility of C-arm-supported CT fluoroscopy in percutaneous abscess drainage procedures

PURPOSE

Evaluation of C-arm-supported CT fluoroscopy to facilitate percutaneous abscess drainage procedures.

METHODS

Prospectively, 40 percutaneous drainage procedures were performed either with C-arm-supported CT fluoroscopy or with CT fluoroscopy alone. Hybrid imaging was performed on the CT couch after complementing a CT fluoroscopy scanner with a C-arm fluoroscopy unit. Procedure times, drainage revisions during follow-up, and postinterventional drainage periods were analyzed.

RESULTS

When compared with exclusive CT fluoroscopic guidance, a median procedure time of 9 +/- 3.7 min versus 14.8 +/- 7.3 min was required for C-arm-supported CT fluoroscopy (p < 0.005, t-test). During follow-up, eight drainage catheters had to be revised within the exclusive CT fluoroscopy group, while only two revisions were necessary within the C-arm-supported CT fluoroscopy group. With C-arm-supported CT fluoroscopy, postinterventional drainage periods were reduced (median 13 vs 19 days; p < 0.001, t-test).

CONCLUSION

Compared with exclusive cross-sectional image guidance, C-arm-supported CT fluoroscopy seems to improve placement of abscess drainage catheters to possibly reduce procedure times, drainage catheter revisions, and postinterventional drainage periods.

Quantitative human in vivo evaluation of high resolution MRI for vessel wall morphometry after percutaneous transluminal angioplasty

Visualization of the vessel wall after transluminal angioplasty is important to monitor the restenosis progress. Intravascular ultrasound proved its capabilities as an invasive procedure in many studies. The aim of this study was to evaluate the feasibility of high-resolution MRI as a non-invasive tool for follow-up after PTA. High-resolution magnetic resonance images (pixel size: 0.49 * 0.49 mm(2)) were acquired on a 1.0 T clinical scanner. Morphometry was conducted after conversion of DICOM images into TIFF format using ScionImage on a PC. In-vitro studies using a polyvinylchloride tube were evaluated by two independent investigators. Goldstandard was a caliper rule and direct radiography. Five patients were monitored before and 24 h, six weeks, three months and six months after PTA. In vivo measurements promised a good concordance for both investigators for area as well as for diameter measurements. Area measurements showed correlations up to r = 0.86 (p < 0.001) whereas the correlations of diameters were slightly inferior (r between 0.58 and 0.84; p < 0.005). Relocation of the same slice position in the follow up studies could be guaranteed using anatomic landmarks in the images. As a non-invasive tool to assess restenosis after PTA high-resolution MRI promises to be a reproducible technique. It is easy to identify the same vascular region in different studies due to neighboring anatomic landmarks. Progression of disease as well as success of pharmacologic treatment to prevent restenosis may be monitored.

Imaging procedures in neuroendocrine tumours

PURPOSE

To give recommendations for diagnostic imaging workflow in suspected neuroendocrine tumours.

MATERIALS AND METHODS

Recommendations for imaging workflow were elaborated by consensus of researchers in neuroendocrine tumours.

RESULTS

Workflow charts are presented for: (1) nonfunctional and functional endocrine tumours of the pancreas (except insulinoma); (2) insulinoma; (3) ECL cell tumour; (4) assessment of unknown primaries in functional and nonfunctional neuroendocrine tumours of the gut; (5) assessment of metastases in functional and nonfunctional neuroendocrine tumours of the gut.

CONCLUSIONS

The workflow charts facilitate diagnosis of neuroendocrine tumours as well as the design of controlled studies.

Magnetic resonance colonography and virtual magnetic resonance colonoscopy with the 1.0-T system: a feasibility study

RATIONALE AND OBJECTIVES

An ex vivo study and a clinical, prospective, patient study were undertaken to evaluate the feasibility of magnetic resonance (MR) colonography with a 1.0-T system.

METHODS

An ex vivo colon model was scanned. A cleaned pig colon was prepared with six simulated sessile polyps (diameters of 4-12 mm) and one simulated pedunculated polyp (diameter of 5 mm). Subsequently, five patients (aged 39-81 years; four women, one man) were examined with MR colonography, immediately followed by endoscopic colonoscopy. After preparation for colonoscopy, the colon was filled with a Gd-DTPA/water solution (1:100). A breath-hold 3D gradient-echo sequence was acquired in both the prone and supine positions and after intravenous Gd-DTPA administration. Images were analyzed interactively by using multiplanar projections, maximum-intensity projection, and a virtual endoscopic view. The MR results were compared with the findings of the fiberoptic endoscopy.

RESULTS

All seven simulated lesions of the colon model could be detected by MR imaging. In one patient, an advanced colon cancer as well as an additional small polyp was depicted. In the other four patients, single polyps with a diameter of 1 to 2.5 cm and a large adenoma were visualized by MR colonography. Contrast enhancement of the polyps was noted only after subtraction.

CONCLUSIONS

The 1.0-T system is feasible for MR colonography. Reduced requirements for hardware could contribute to establish the novel technique as a screening method for colorectal polyps.

Are covered stents really effective at closing esophagotracheal fistulas? Results of an animal study

PURPOSE

To determine whether covered self-expanding metal stents successfully exclude experimentally created esophagotracheal fistulas.

METHODS

Esophagotracheal fistulas were surgically created in the upper third of the esophagus in 12 minipigs and immediately sealed by implantation of a covered self-expanding metal stent (20 mm expanded diameter) in the esophagus. Before the animals were killed, after 3, 7, 14, 28, 30, and 36 days, the position of the stent and the sealing of the fistula were monitored fluoroscopically. The esophagus, trachea, and both lungs were examined histologically.

RESULTS

Creation of an esophagotracheal fistula was successful in all cases. All fistulas were widely patent at autopsy. The technical success rate for stent deployment and initial sealing of the fistula was 100%. During follow-up, five stents migrated distally, but none into the stomach. Therefore, the fistula was no longer excluded in five animals. In seven animals the stent sealed the fistula until the death of the animal. Tracheal narrowing necessitated additional tracheal stenting in three animals. Two minipigs died due to aspiration of food. Histologic examination showed signs of aspiration in all animals with stents in place for longer than 2 weeks.

CONCLUSION

This experimental animal study revealed worse results for sealing of esophagotracheal fistulas with covered self-expanding metal stents than have been reported for the clinical use of these devices.

Mid-term follow-up after percutaneous hydrodynamic thrombectomy in lower limb ischemia: initial experience with two-dimensional MR imaging and three-dimensional MR angiography

PURPOSE

To assess noninvasively mid-term patency, reocclusion, and mid-term changes of the arterial wall after percutaneous hydrodynamic thrombectomy in patients with acute lower limb ischemia using magnetic resonance (MR) imaging/MR angiography (MRA).

MATERIALS AND METHODS

Arterial wall and luminal changes were evaluated in 16 patients (10 men, six women; mean age, 70 years), with a minimum follow-up of 12 months after percutaneous thrombectomy with a hydrodynamic catheter for acute lower limb ischemia (embolic, n = 5; thrombotic, n = 11). Adjunctive PTA was performed in 44%. The mean follow-up was 23 months +/- 7.6 (range, 12-33 months). MR imaging and MRA were performed on a 1.0 T system using an extremity coil and two-dimensional (2D) time-of-flight, turbo spin echo, 2D gradient echo, and contrast enhanced three-dimensional (3D) gradient echo sequences.

RESULTS

In one patient, a complete reocclusion was noted and, in two patients, a hemodynamically insignificant restenosis (< or = 50%) was identified with MR imaging. This was in accordance with color flow duplex sonography, physical examination, ankle/brachial index measurements, and the treadmill test. The MR morphometry documented an increase of the entire vessel area from 48.9 mm2 +/- 3.3 (control segments) to 55.5 mm2 +/- 2.8 at the treated segments (+13.3%; P < .05). The vessel wall area increased from 31.7 mm2 +/- 1.8 to 39.4 mm2 +/- 2.3 (+24.4%; P < .05). The mean area stenosis grade was 12%.

CONCLUSION

MR imaging with use of morphometric analysis is a possible tool to noninvasively determine the mid-term patency and restenosis/reocclusion and remodeling process after percutaneous thrombectomy and other interventional procedures.

Prospective comparison of magnetic resonance sialography and digital subtraction sialography

We sought to compare the diagnostic utility of magnetic resonance sialography (MRS) and digital subtraction sialography (DSS) in patients with suspected sialolithiasis or sialadenitis. Sixteen consecutive patients (4 female and 12 male, mean age 51+/-16 years) with suspected sialolithiasis or sialadenitis underwent DSS by a standard technique and MRS. MRS was obtained with a T2-weighted single-shot TSE sequence (TR/TE 2800/1100 msec, acquisition time 7 seconds) using a quadrature head (n = 16) and a surface coil (n = 8). Nineteen symptomatic glands were investigated with DSS: eight submandibular glands in 6 patients (two bilateral) and unilateral parotid glands in 11 patients. MRS was always carried out to visualize gland ducts bilaterally. The ductal system was visualized in all glands examined by MRS. DSS depicted the ductal system in all 11 parotid glands, but only 4 of the 8 submandibular glands (50%). Sialolithiasis was diagnosed in three cases (one parotid, two submandibular glands) by MRS and in two cases by DSS. DSS demonstrated tertiary branching ducts and MRS secondary branching ducts. MRS is able to visualize the ductal system of the parotid and submandibular gland noninvasively and is thus not dependent on successful cannulation of the orifice of the ductal system. Our preliminary data indicate that MRS is useful for diagnosing sialolithiasis. MRS allows diagnosis of sialadenitic changes, but DSS achieves a better diagnostic performance due to higher spatial resolution.

Nitric oxide inhibits the basic fibroblast growth factor-stimulated migration of bovine vascular smooth muscle cells in vitro

BACKGROUND

The purpose of this study was to evaluate the effect of nitric oxide (NO) on basic fibroblast growth factor (bFGF)-stimulated migration of bovine VSMC in vitro.

METHODS

For the migration assay 50,000 cells from passages 4 to 8 were put into a migration chamber and stimulated with 10 ng bFGF/ml (control group). For another experiment, the NO donator sodium nitroprusside (SNP) (10(-6), 10(-8), 10(-10) M), the second messenger of NO 8-bromo-cGMP (10(-6), 10(-8), 10(-10) M) and 100 U of superoxide dismutase (SOD) were added. Migration of cells was quantified after fixing and staining of the cells by means of light microscopy.

RESULTS

Cell migration was significantly inhibited by SNP in a dose dependent manner (p < 0.01 with t-test). This effect was mirrored by 8-bromo-cGMP and not significantly inhibited by SOD, confirming this to be an NO mediated effect and excluding side-effects of superoxide-derived oxidation products.

CONCLUSION

Nitric oxide inhibits the basic fibroblast growth factor stimulated migration of bovine vascular smooth muscle cells in vitro.

[X-rays taken by radiologists! Influence on a continuous quality improvement process?]

PURPOSE

To evaluate how the training of radiology residents in taking radiographs influences the work of radiographers and the established quality standards.

METHODS

A first year radiology resident was trained for 4 weeks in focusing and exposure techniques by radiographers. In a second period the resident took 582 radiograms, which were compared with those taken by technicians for error estimation on a daily basis. During a third period the radiographs were produced in a contest between the resident and a skilled radiographer. Errors were analyzed by two independent experts according to established guidelines of the German Medical Association.

RESULTS

At the beginning of the second period the average error rate of the resident was 11.9% as compared to 8.9% in the technicians team, in the following month 9.2% versus 15.9%. In the third period no relevant difference in errors could be observed. Finally, unexpected quality improvements were implemented like an improved standardization of focusing and exposure techniques as well as dose reduction.

CONCLUSIONS

Radiology residents easily learn focusing and exposure techniques and achieve comparable results as radiographers within a short period of time. The additionally achieved knowledge improves the technical process of taking radiographs. We recommend to include a two plane radiography training period in the curriculum of radiology residents. It reinforces the radiologist's role in continuous quality improvements of the diagnostic process.

Comparison of C-arm CT fluoroscopy and conventional fluoroscopy for percutaneous biliary drainage procedures

PURPOSE

To conduct a prospective randomized evaluation of C-arm computed tomography (CT) fluoroscopy for external biliary drainage procedures in comparison with conventional fluoroscopic guidance to reduce the number of transhepatic punctures as a primary endpoint.

MATERIALS AND METHODS

In 18 patients with biliary obstructions, 20 external percutaneous biliary drainage procedures were prospectively performed with use of either C-arm CT fluoroscopy or conventional fluoroscopy alone. The number of hepatic punctures, procedure time, and fluoroscopy time, were analyzed separately for both methods.

RESULTS

C-arm CT fluoroscopy resulted in a reduced number of transhepatic punctures, with decreased procedure and fluoroscopy times (P < .05; t test). When compared with conventional external biliary drainage procedures, a mean of 1.8+/-1 versus 4.8+/-2.8 hepatic punctures at a fluoroscopy time of 3.4+/-1.5 versus 11.4+/-7.4 minutes was required for C-arm CT fluoroscopy, while procedure times were 11+/-3.6 versus 16.2+/-9.3 minutes.

CONCLUSIONS

C-arm CT fluoroscopy is associated with decreased procedure and fluoroscopy times, while fewer transhepatic punctures are required to establish external biliary drainage.

[Angiography detection of closed palmar arcs]

PURPOSE

Angiographic evaluation of the prevalence of an anastomosis between the superficial and deep palmer arcs in our patients.

MATERIALS AND METHODS

Between January 1st 1991 and December 31st 1997, all selectively performed angiographies of the upper extremities were evaluated retrospectively with special focus on an anastomosis between the superficial palmer arc (SPA) and the deep palmer arc (DPA). The indications for performing a selective angiography of the upper extremity were presurgical planning of a skin/muscle transplantation (n = 42), creation of a hemodialysis fistula (n = 4) and evaluation of vascular diseases such as vasculitis (n = 9), peripheral occlusive disease (n = 3) and M. Winiwarter-Buerger (n = 8).

RESULTS

66 selective angiographies of the palm of 60 patients (39 male, 21 female, mean age 52 years old) could be used for evaluation. Angiographies of both hands were performed in 6 patients. Closed superficial palmar arcs and closed deep palmar arcs were detected in 31.8% and 84.8% of the patients, respectively.

CONCLUSIONS

The rates of anastomosed superficial and deep palmar arcs in our study are comparable with those of former angiographic investigations, but they are considerably lower than the rates based on anatomical or sonographical studies. Reasons for the discrepancy are discussed.

Differential gene expression of vascular smooth muscle cells. Detection by RNA arbitrarily primed polymerase chain reaction

BACKGROUND

Vascular smooth muscle cells (VSMC) play an important role in the development of restenotic lesions. However, regulation of proliferation, migration, and matrix synthesis of these cells is still poorly understood. The aim of this study was to analyze gene expression of differently stimulated bovine VSMC.

MATERIAL AND METHODS

RNA was isolated from stimulated bovine VSMC after different time periods. For stimulation we used growth factors (platelet-derived growth factors PDGF-AA, PDGF-BB, basic fibroblast growth factor) and a nitric oxide donating drug (sodium nitroprusside). Gene expression of stimulated and control cells was analyzed by non-radioactive RNA fingerprinting (RNA arbitrarily primed polymerase chain reaction, RAP-PCR) and standard gel electrophoresis. Polymorphic fragments were sequenced and further characterized.

RESULTS

By RAP-PCR we detected changes in the RNA fingerprint pattern of stimulated cells compared with unstimulated cells. Sequences of five fragments out of 12 showed high homology to known human genes (serine-methyl-transferase, DUTT1, laminin B2, a newly cloned translational regulator (p97), and a human expressed sequence tag). For laminin B2 we could confirm an upregulation after stimulation with growth factors at 1 and 6 hours and after stimulation with SNP at 1 hour in comparison to controls. For p97 we could show a downregulation after stimulation with SNP, bFGF and PDGF-BB but not PDGF-AA.

CONCLUSION

RAP-PCR is well suited for analysis of VSMC gene expression in vitro. The laminin B2 and p97 gene are differently expressed after growth factor stimulation in bovine VSMC.

Combination therapy with octreotide and alpha-interferon: effect on tumor growth in metastatic endocrine gastroenteropancreatic tumors

OBJECTIVE

We investigated the antiproliferative efficacy of the addition of alpha-interferon to the somatostatin analogue octreotide in patients with metastasized gastroenteropancreatic tumors unresponsive to octreotide monotherapy.

METHODS

In an open prospective trial, 21 patients with metastasized neuroendocrine gastroenteropancreatic tumors (nine patients with carcinoid syndrome, eight with nonfunctioning tumors, four with gastrinoma) were treated with 5 x 10(6) IU alpha-interferon tiw in addition to 200 microg of octreotide tid. All patients, including 16 patients with preceding monotherapy with 200 microg of octreotide tid, had tumor progression documented by computed tomography before entering the study. Growth response (computed tomography documented) and biochemical response were assessed at 3-month intervals.

RESULTS

Inhibition of tumor growth was observed in 14 patients (67%), 11 of whom had preceding octreotide monotherapy; complete regression was observed in one patient lasting for 49 months and stable disease (stand-still) in 13 patients lasting for 3 to 52 months (median, 12 months). Seven patients failing this combination therapy exhibited a significantly shorter overall survival (median, 23 months; range, 5 to 42 months) than the 14 patients responding to this regimen (median, 68 months; range, 12 to 112 months; p = 0.007). Two patients are still alive. Biochemical response was achieved in 69% of patients with functioning tumors: in three of four patients with gastrinoma and in six of nine patients with carcinoid syndrome.

CONCLUSIONS

These data suggest that the addition of alpha-interferon to octreotide has antiproliferative efficacy in a subgroup of patients with advanced metastatic disease unresponsive to octreotide monotherapy. Prolonged survival was seen in the responder group.

[Pulmonary, nodular cavernous, calcifying form of amyloidosis]

We report a rare case of pulmonary nodular amyloidosis featuring all typical morphologic alterations associated with this disease; multiple amyloidomas, calcification and cavernous transformation were present. Definite diagnosis was established histologically with CT-guided biopsy. The different types of pulmonary amyloidosis and their radiological appearances are described and discussed.

[Definition and specification requirements for PAC-systems (picture archiving and communication system). A performance index with reference to the standard "IEEE Recommended Practice for Software Requirement Specifications"]

PROBLEM

The formulation of requirements is necessary to control the goals of a PACS project. Furthermore, in this way, the scope of functionality necessary to support radiological working processes becomes clear.

METHOD

Definitions of requirements and specification are formulated independently of systems according to the IEEE standard "Recommended Practice for Software Requirements Specifications". Definitions are given in the Request for Information, specifications in the Request for Proposal. Functional and non-functional requirements are distinguished. The solutions are rated with respect to scope, appropriateness and quality of implementation.

RESULTS

A PACS checklist was created according to the methods described above. It is published on the homepage of the "Arbeitsgemeinschaft Informationstechnologie" (AGIT) within the "Deutsche Röntgengesellschaft" (DRG) (http://www.uni-marburg.de/mzr/agit).

CONCLUSION

The checklist provides a discussion forum which should contribute to an agreement on accepted basic PACS functionalities.

Effects of nitinol Strecker stent placement on vascular response in normal and stenotic porcine iliac arteries

PURPOSE

This experimental study was conducted to evaluate neointimal thickness, lumen diameters, and histologic changes in normal and stenotic porcine iliac arteries following placement of self-expanding nitinol Strecker stents.

MATERIALS AND METHODS

Neointimal trauma causing slight vascular stenosis was induced unilaterally within external iliac arteries of 12 swines by means of endothelial abrasion and high cholesterol diet. Nitinol Strecker stents were placed within the stenotic and the normal contralateral vascular segments. For histopathologic evaluation, the pigs were killed 12 or 24 weeks after stent placement and luminal diamters were evaluated angiographically.

RESULTS

Excluding one occlusion, 15% narrowing of the lumen diameter was induced unilaterally (P = .002). Initial luminal gain after stent placement was greater for stenotic than for normal arteries. The amount of neointima thickness was not different between stenotic and normal vessels (P > .05). Comparing vascular diameters before stent placement and at follow-up, luminal loss due to neointima proliferation was 22% within normal arteries (P = .0002), while a luminal gain by 15% was found within the stenotic arteries (P = .008). Maturation of neointima and endothelial coverage were complete after 24 weeks.

CONCLUSIONS

Even though nitinol Strecker stents induce excessive neointimal proliferation, stenotic arteries seem to profit from great early luminal gain resulting in 15% of vascular expansion at follow-up while slight stenosis is induced within normal iliac arteries.