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Biomedical subjects

Hans-Peter Dinkel

Publications and source records attributed to Hans-Peter Dinkel.

At least 19 recordsLinked to original sources
PubMed2005

Importance of extracolonic findings at IV contrast medium-enhanced CT colonography versus those at non-enhanced CT colonography.

To compare the clinical importance of extracolonic findings at intravenous (IV) contrast-enhanced CT colonography versus those at non-enhanced CT colonography. IV contrast medium-enhanced (n=72) and non-enhanced (n=30) multidetector CT colonography was performed in 102 symptomatic patients followed by conventional colonoscopy on the same day. The impact of extracolonic findings on further work up and treatment was assessed by a review of patient records. Extracolonic findings were divided into two groups: either leading to further work up respectively having an impact on therapy or not. A total of 303 extracolonic findings were detected. Of those, 71% (215/303) were found on IV contrast-enhanced CT, and 29% (88/303) were found on non-enhanced CT colonography. The extracolonic findings in 25% (26/102) of all patients led to further work up or had an impact on therapy. Twenty-two of these patients underwent CT colonography with IV contrast enhancement, and four without. The percentage of extracolonic findings leading to further work up or having an impact on therapy was higher for IV contrast-enhanced (31%; 22/72) than for non-enhanced (13%; 4/30) CT scans (P=0.12). IV contrast-enhanced CT colonography produced more extracolonic findings than non-enhanced CT colonography. A substantially greater proportion of findings on IV contrast-enhanced CT colonography led to further work up and treatment than did non-enhanced CT colonography.

Adenocarcinoma↗
PubMed2005

Optimization of MDCT of the wrist to achieve diagnostic image quality with minimum radiation exposure.

OBJECTIVE: This study tests various acquisition and reconstruction protocols for MDCT of the wrist to determine the optimal protocol for obtaining diagnostic image quality with minimal radiation exposure. MATERIALS AND METHODS: Thirty anatomic specimens were examined with an MDCT collimation of 4.0 x 1.0 mm and 2.0 x 0.5 mm (80, 120, and 140 kV; 80, 100, 130, 160, and 200 mA; rotation time, 0.5 0.75, 1.0 sec; pitch, 1.0, 1.3, 1.5, and 2.0). Coronal images were reconstructed using a slice thickness of 0.5, 1.0, and 2.0 mm with 60% overlap. Three observers evaluated all images independently for gross and fine anatomic detail. Diagnostic confidence was tested using Shrout-Fleiss intraclass correlation coefficients. Interobserver agreement was assessed by Kappa statistics and the Kruskal-Wallis test. RESULTS: Fine anatomic detail was best presented in 0.5-mm or 1.00-mm reconstructions based on a 2.0 x 0.5 mm acquisition. A rotation time of > or = 0.75 sec resulted in fewer artifacts; a significant dose reduction was achieved with 80 kV and 100 mA at the expense of somewhat increased noise, but without significant loss of anatomic detail in bone presentation. Artifacts were tolerable with a pitch of 1.5 or less. CONCLUSION: MDCT at the described optimal settings allows significant dosage reduction without sacrificing image quality. An acquisition and reconstruction thickness of 0.5 mm results in the best depiction of anatomic detail. A reconstruction thickness of 1.0 mm with a reconstruction interval of 0.5 mm represents a good trade-off between noise and resolution when using low-dose protocols.

Aged↗
PubMed2004

Combined surgical and endovascular approach to treat a complex aortic coarctation without extracorporeal circulation.

Various therapeutic approaches have been proposed to treat complex coarctation of the aorta (eg, recoarctation, which requires repetitive interventions, or coarctation with a hypoplastic aortic arch). Resection followed by end-to-end anastomosis or by graft interposition is technically demanding and exposes the patient to considerable perioperative risks. Cardiopulmonary bypass and deep hypothermic circulatory arrest may be necessary to control the distal aortic arch. The role of stent technology in treating this type of lesion has not yet been defined. We present a 21-year-old woman with a recurrent coarctation of the aorta associated with a hypoplastic aortic arch and a pseudoaneurysm of the proximal descending aorta. She had undergone 4 previous interventions. Treatment consisted of a combined surgical and endovascular approach without cardiopulmonary bypass and included extraanatomic aortic bypass, partial debranching of the supraaortic vessels, and stent-graft insertion to exclude the aneurysm.

Adult↗
PubMed2004

Prospective comparison of contrast enhanced CT colonography and conventional colonoscopy for detection of colorectal neoplasms in a single institutional study using second-look colonoscopy with discrepant results.

BACKGROUND: Colorectal cancer is the second leading cause of death from cancer in Western countries. Early detection by colorectal cancer screening can effectively cut its mortality rate. CT colonography represents a promising, minimally invasive alternative to conventional methods of colorectal carcinoma screening. AIMS: The purpose of this prospective single institutional study was to compare the abilities of routine clinical CT colonography and conventional colonoscopy to detect colorectal neoplasms using second-look colonoscopy to clarify discrepant results. PATIENTS AND METHODS: CT colonography was performed in 100 symptomatic patients using contrast enhanced multidetector CT followed by conventional colonoscopy on the same day. If results were discrepant, a second-look colonoscopy was performed after unblinding. CT colonographic findings were compared with those of conventional colonoscopy. RESULTS: Conventional colonoscopy found 122 colorectal neoplasms in 49 patients. The overall sensitivity of CT colonography at detecting patients with at least one polyp 6 mm or larger was 76% and its specificity was 88%. Its by-patient sensitivity for polyps 10 mm or larger was 95% and its specificity was 98%. By-polyp sensitivities were 71% for polyps 10 mm or larger, and 61% for polyps 6 mm or larger. A second-look colonoscopy was performed in 19 patients and two initial false-positive findings of CT colonography were reclassified as true-positive. For conventional colonoscopy, this produced a by-polyp sensitivity of 94% for detection of lesions 6 mm and larger. CONCLUSIONS: CT colonography had both a high by-patient sensitivity and specificity for detection of clinically important colorectal neoplasms 10 mm or larger. This suggests that CT colonography has the potential to become a valuable clinical screening method for colorectal neoplasms.

Adult↗
PubMed2004

Grading airway stenosis down to the segmental level using virtual bronchoscopy.

OBJECTIVE: To assess the sensitivity of noninvasive virtual bronchoscopy based on multirow detector CT scanning in detecting and grading central and segmental airway stenosis using flexible bronchoscopic findings as the reference standard. MATERIALS AND METHODS: In a blinded controlled trial, multirow detector CT virtual bronchoscopy and flexible bronchoscopy were used to search for and grade airway stenosis in 20 patients. CT scan data were obtained with a multirow detector CT scanner using 4 x 1 mm collimation. Flexible bronchoscopy findings were graded by a pulmonologist and served as the reference standard for 176 central airway regions (ie, trachea, main bronchi, and lobar bronchi) and 302 segmental airway regions. The extent of airway narrowing was categorized as grade 0 (no narrowing), grade 1 (< 50%), or grade 2 (> or =50%). RESULTS: Flexible bronchoscopy revealed 30 stenoses in the central airways and 10 in the segmental airways. Virtual bronchoscopy detected 32 stenoses in the central airways (sensitivity, 90.0%; specificity, 96.6%; accuracy, 95.5%) and 22 in the segmental airways (sensitivity, 90.0%; specificity, 95.6%; accuracy, 95.5%). The number of false-positive findings was higher in the segmental airways (13 false-positive findings) than in the central airways (5 false-positive findings), which caused a lower positive predictive value for the segmental airways (40.9%) than for the central airways (84.4%). Flexible and virtual bronchoscopic gradings correlated better for central airway stenosis (r = 0.87) than for segmental airway stenosis (r = 0.61). CONCLUSION: Although a high sensitivity was found for the detection of both central and segmental airway stenosis, the number of false-positive findings was higher for segmental airways. However, noninvasive multirow detector CT virtual bronchoscopy enables high-resolution endoluminal imaging of the airways down to the segmental bronchi.

Aged↗
PubMed2004

Multidetector CT angiography versus digital subtraction angiography for aortoiliac length measurements prior to endovascular AAA repair.

PURPOSE: To assess observer variation between calibrated-catheter digital subtraction angiography (DSA) and software-enhanced multidetector computed tomography angiography (CTA) in measuring vessel length prior to endovascular aortic aneurysm repair (EVAR). METHODS: Thirty patients (25 men; mean age 65 years, range 61-85) scheduled for EVAR underwent CTA in 4x2-mm collimation using advanced vessel analysis software. CTA measurements were performed twice by 2 blinded readers in random order with at least a 4-week interval between readings. Nine patients were found unsuitable for endovascular repair after the CTA, so DSA was performed in 21 patients for morphometric evaluation of the abdominal aorta and the iliac arteries. The following segments were measured: H1 (aneurysm neck), H2 (lower renal artery to distal aspect of the aneurysm), H3 (lower renal artery to aortic bifurcation), and H4a/H4b (lower renal artery to iliac bifurcations). Length measurements on DSA were made by (1) following the catheter path in the aortic lumen and (2) dividing tortuous vessel anatomy into segments and measuring each segment along an idealized centerline. Addition of the various segments allowed comparison with data obtained from CTA measurements. RESULTS: CTA was performed with good intraobserver agreement for all length parameters except H3 in reader 2 (p<0.05). While good interobserver agreement was demonstrated for CTA over long aortoiliac distances (H4a, H4b), higher interobserver agreement was obtained with DSA for shorter segments (H1, H2). Considerable differences were observed between CTA and DSA for the lengths H2 and H4b. CONCLUSIONS: CTA produces better intra and interobserver correlations in measuring vessel length than DSA. It has the potential to replace DSA as an imaging method before EVAR.

Aged↗
PubMed2004

Virtual colon dissection with CT colonography compared with axial interpretation and conventional colonoscopy: preliminary results.

OBJECTIVE: The aim of this study was to determine whether a new virtual colon dissection 3D visualization technique for CT colonography has a shorter analysis time and better sensitivity for detection of colonic polyps than interpretation of axial CT images. SUBJECTS AND METHODS. CT colonography was performed in 22 patients using 4-MDCT followed by conventional colonoscopy on the same day. The CT colonography data sets were analyzed by virtual colon dissection, which virtually bisects and unfolds the colon along its longitudinal axis to inspect the inner colonic surface for polyps. The same CT data sets were independently evaluated using axial interpretation. All data sets were independently interpreted by two radiologists in a blinded manner. RESULTS: Conventional colonoscopy revealed 31 colonic lesions in 20 patients. Twenty two of the lesions were smaller than 10 mm; nine were 10 mm or larger. Two of the original 22 patients were excluded, one because of residual stool and fluid and the other because of an impassable stenosing rectal wall cancer. For virtual colon dissection, the per-lesion sensitivity was 42% for observer 1 and 68% for observer 2; for axial interpretation, the respective sensitivities were 48% and 61%. For polyps 10 mm or larger, the respective sensitivities were 67% and 89% for virtual colon dissection and 89% and 100% for axial interpretation. The average time for reconstruction and analysis of virtual colon dissection was 36.8 min versus 29.2 min for axial images. Virtual colon dissection was feasible in both the supine and the prone positions in 45.5% of colonic segments, in either the supine or the prone position in 24.5%, and in neither position in 30% of segments. CONCLUSION: Although virtual colon dissection may facilitate detection of colonic polyps in isolated cases, its detection rate is not superior to axial interpretation, which is mainly attributable to failed rendering of insufficiently distended colonic segments or regions with residual feces. Virtual colon dissection is also the more time-consuming of the two procedures. With further improvement of path-finding and image segmentation, however, virtual colon dissection has the potential to be a useful interpretation tool for CT colonography.

Adult↗
PubMed2003

Percutaneous treatment of placenta percreta using coil embolization.

PURPOSE: To report the use of embolotherapy to avoid hysterectomy in rare placenta percreta. CASE REPORT: A pregnant 34-year-old woman (gravida 3, para 2) was admitted with premature rupture of membranes and vaginal bleeding in the 32nd week. Prenatal B-mode and Doppler ultrasound revealed marked hypervascularity of the placenta with disruption of the uterine-bladder interface consistent with placenta percreta. Since the patient insisted on uterine preservation, uterus and placenta were left in situ after caesarean section, which was followed by coaxial microcoil embolization of 6 pelvic arteries and postoperative methotrexate administration. Three months later, the patient had severe bleeding from the retained placenta, possibly under the influence of anticoagulation administered for pulmonary embolism. Emergent hysterectomy was performed. CONCLUSIONS: Coil embolization may avoid immediate hysterectomy and reduce peri-delivery blood loss in placenta percreta. However, retained placenta poses a serious risk, even after months, and secondary hysterectomy should be performed as an elective procedure after embolization.

Adult↗
PubMed2003

Endovascular treatment of malignant superior vena cava syndrome: is bilateral wallstent placement superior to unilateral placement?

PURPOSE: To report our experience with unilateral versus bilateral stent placement in the treatment of malignant superior vena cava syndrome (SVCS). METHODS: The records and films of 84 consecutive patients (69 men; mean age 64+/-10 years, range 39-79) referred for stent placement in malignant SVCS were reviewed for venous compromise, technical and clinical success, complications, and reocclusions. Wallstents were placed covering the SVC and both (bilateral technique) brachiocephalic veins (BCV) preferentially; unilateral stenting of only one BCV in addition to the SVC was performed based on operator preference or inability to access both sides. Technical success was defined as the ability to stent the SVC and at least one BCV; clinical success was the elimination of SVCS symptoms. RESULTS: Technical success was achieved in 83 (99%) patients, using the unilateral technique in 22 and bilateral stenting in 61 patients. The groups did not differ with regard to age, sex, underlying diseases, or location and extent of venous compromise. Immediate clinical success was achieved in 20 (91%) of 22 patients in the unilateral group and 55 (90%) of 61 patients in the bilateral group. Two patients suffered late occlusion in the unilateral group, while in the bilateral group, 8 patients had early occlusion and 9 had late occlusion. Thus, the total occlusion rate was significantly (p<0.05) lower in the unilateral group. There was 1 other complication (pericardial tamponade) in the bilateral group, for a 28% total complication rate, which was significantly higher (p=0.039) than the 9% in the unilateral group. The 1, 3, 6, and 12-month primary stent patency rates were 90%, 81%, 76%, and 69%, respectively. Patency tended to last longer in the unilateral group, but the difference was not significant (p=0.11). CONCLUSIONS: Although bilateral Wallstent placement achieved equal technical and clinical success, it tended to confer shorter-lived patency and caused more complications.

Adult↗
PubMed2002

Low-dose multislice CT of the thorax in follow-up of malignant lymphoma and extrapulmonary primary tumors.

Our objective was to study the impact of low-dose multislice thoracic CT on image quality and lesion conspicuity in follow-up of patients with malignant lymphoma and extrapulmonary primary tumors. Forty consecutive patients with a history of malignant lymphoma or extrapulmonary malignant primaries who had undergone previous standard-dose thoracic spiral CT (120 kVp, 150 mAs, 8 mm) were subjected to low-dose multislice CT (15 mAs/rotation, 120 kVp, pitch 1.5, 4x2-mm collimation reconstructed to contiguous 8-mm slices. Image quality and lesion conspicuity were classified independently by two readers on a four-point ordinal scale (1=poor, 4=excellent). Mean image quality was significantly lower for low-dose CT, 2.35, than for standard-dose CT, 3.25 ( p<0.001); however, all low-dose CT examinations were fully readable, none had to be repeated, and no lesions (including 51 lung lesions and 31 soft tissue lesions) remained undetected. Only in the apical lung did the lowered tube current significantly reduce lesion conspicuity. Even in pulmonary lesions smaller than 10 mm ( n=21) lesion conspicuity did not significantly differ between standard and low-dose scans. Low-dose thoracic multislice CT based on a 90% reduction in dose compared with standard-dose techniques was not associated with impaired detection of suspicious lesions and may be useful in follow-up of malignant lymphoma and extrapulmonary tumors.

Female↗
PubMed2002

Emergency percutaneous retrieval of a silicone port catheter fragment in pinch-off syndrome by means of an Amplatz gooseneck snare.

Rupture of a silicone Port-a-Cath catheter may occur, especially with costoclavicular pinch-off syndrome (POS), which is a typical consequence of fatigue when the catheter is introduced in the subclavian vein too medially. This case report describes the percutaneous retrieval of a fractured silicone port catheter fragment, which had migrated into the internal jugular vein. Extraction was complicated by the presence of an internal jugular vein stenosis and the fact that the catheter fragment was looped upon itself. Several retrieval devices failed before an Amplatz gooseneck snare finally allowed retrieval of the fragment. We recommend this device for extraction of silicone port catheter fragments. Rerupture of the port catheter occurred 7 months after surgical reinsertion at the same infraclavicular site, as a consequence of constant compression by POS. Alternative approaches should be used after catheter failure due to POS.

Journal Article↗
PubMed2002

Subtotal colectomy with primary ileorectostomy is effective for unlocalized, diverticular hemorrhage.

BACKGROUND: A large proportion of patients with acute colonic diverticular bleeding undergo emergency surgery without successful prior localization of the bleeding site. This study sought to determine the surgical techniques of choice for unlocalized, diverticular hemorrhage. METHODS: We reviewed the data on 42 consecutive patients (median age 76 years, range 44-91) with acute colonic diverticular bleeding operated on between November 1993 and December 2000. Mean follow-up was 4.1 years. RESULTS: Preoperative localization of the bleeding site was possible in six patients (14%), by colonoscopy in two and by angiography in four. Ten patients underwent segmental colectomy with primary anastomosis (5 "directed", 5 "blind") and 32 subtotal colectomy with primary ileorectostomy (1 "directed", 31 "blind"). Subtotal colectomy is the more extensive surgical procedure (longer resected bowel, greater blood loss), and although it was performed in older patients, there were no significant differences between segmental and subtotal colectomy with respect to operation time, morbidity, mortality, hospital stay, number of bowel movements, continence scores, rebleeding rate, or patient satisfaction. CONCLUSIONS: Subtotal colectomy with primary ileorectostomy for unlocalized colonic diverticular bleeding is a safe and effective surgical procedure providing complete bleeding control and preserving continence.

Adult↗
PubMed2002

Pulmonary arteriovenous malformations: embolotherapy with superselective coaxial catheter placement and filling of venous sac with Guglielmi detachable coils.

PURPOSE: To assess the value of superselective embolotherapy of pulmonary arteriovenous malformations (PAVMs) with coaxial microcatheters and 0.018-inch microcoils and to evaluate the technique of filling the venous sac with Guglielmi detachable coils (GDCs). MATERIALS AND METHODS: Six consecutive patients (three men, three women; mean age, 46 years, age range, 18-74 years) underwent arterial embolization of nine PAVMs with superselective catheterization with a 3-F coaxial catheter system and embolization with 0.018-inch microcoils. The PAVMs varied in size from 1 to 6 cm (mean, 2.5 cm). Five of the lesions were also treated by filling the venous sac with GDCs. Success and outcome were evaluated by means of a review of patient records, angiographic findings, and telephone interview results. RESULTS: Complete primary occlusion was achieved in eight of nine lesions; repeat embolization resulted in successful occlusion of one lesion. The superselective technique enabled successful embolization in one patient after a previous procedure performed with a 0.035-inch (Gianturco) coil had failed. Filling of the venous sac was performed in the presence of dilated draining veins and enabled successful occlusion of the feeding artery with microcoils in all cases. There were no complications. CONCLUSION: Superselective embolization with microcatheters allowed easy catheterization and safe coil deployment. Filling of the venous sac reliably prevented systemic migration of GDCs in PAVMs with a large venous component.

Adult↗
PubMed2002

Blunt renal trauma: minimally invasive management with microcatheter embolization experience in nine patients.

PURPOSE: To evaluate superselective embolization therapy for the management of arterial damage in patients with severe renal trauma. MATERIALS AND METHODS: Nine consecutive patients with renovascular injuries after blunt trauma underwent superselective embolization. Six patients had pseudoaneurysms or traumatic arteriovenous fistulas. Three patients had frank, uncontained extravasation (two shattered kidneys, one complete pedicle avulsion) and were treated immediately after admission. Two patients were hemodynamically unstable. All patients underwent embolization with 3-F coaxial microcatheters and polyvinyl alcohol particles (n = 2) or 0.018-inch platinum microcoils (n = 7). Procedural and medical success and complications (eg, postembolization syndrome, abscess, permanent serum creatinine elevation, hypertension) were retrospectively assessed from the patients' records. Mean clinical follow-up was 11.9 months (range, 1-50 months). RESULTS: In all cases bleeding was effectively controlled with superselective embolization in a single session. There was no procedure-related loss of renal tissue in eight cases; in one patient, a lower pole remnant of 20% of viable ipsilateral parenchyma was lost due to the procedure. In one patient, a coil migrated into a lumbar artery without causing clinical consequences. None of the patients developed abscess, hypertension, or procedure-related impairment of renal function. CONCLUSION: Superselective embolization may be used for effective, minimally invasive control of active renovascular bleeding.

Adult↗
PubMed2002

Emergent axillary artery stent-graft placement for massive hemorrhage from an avulsed subscapular artery.

PURPOSE: To report the successful endovascular repair of an acute axillary artery hemorrhage. CASE REPORT: An 87-year-old woman with Charcot-Marie-Tooth ataxia presented with an enormous shoulder hematoma and clinical signs of exsanguination after a fall. Angiography demonstrated complete avulsion of the right subscapular artery from the axillary artery, and active bleeding into a hematoma of at least 1500 mL. Endovascular repair with a balloon-mounted covered stent-graft was performed percutaneously, which controlled the bleeding and averted surgery. The patient recovered uneventfully and was without signs of recurrent bleeding or ischemia on the 6-month ultrasound examination; she reports no symptoms referable to her upper extremity after 14 months. CONCLUSIONS: Endovascular repair with stent-grafts is effective in controlling arterial bleeding from supra-aortic vessels even under emergency conditions.

Accidental Falls↗
PubMed2002

Fatal pericardial tamponade after Wallstent implantation for malignant superior vena cava syndrome.

PURPOSE: To report a rare, fatal complication of superior vena cava Wallstent implantation. CASE REPORT: A 59-year-old man presenting with superior vena cava syndrome caused by small-cell lung cancer underwent stent implantation of 2 kissing Wallstents >1.5 cm above the right atrium. Despite correct stent deployment, vessel perforation occurred in a section not encased by tumor, which led to fatal pericardial tamponade shortly after the procedure. Autopsy revealed perforation of a stent strut through the caval wall into the pericardial space. Anatomical and methodological reasons are discussed. CONCLUSIONS: The interventionist should be aware of this rare complication. Alternative stent designs avoiding the sharp ends of Wallstents and Palmaz stents should be considered.

Blood Vessel Prosthesis Implantation↗