PubMed Health⌕ Search

Biomedical subjects

Hilmar Kühl

Publications and source records attributed to Hilmar Kühl.

17 recordsLinked to original sources
PubMed2006

A cemented caval vein filter: case report.

STUDY DESIGN: Case report. OBJECTIVE: To present a previously undescribed complication of bone cement use during spinal surgery. SUMMARY OF BACKGROUND DATA: Surgical cement reaching the circulation is a frequently described complication. The placement of caval vein filters is a routine measure in specific patients to prevent thrombotic material, usually from deep venous thrombosis in the lower extremities, from reaching the pulmonary circulation. A case of bone cement getting trapped in the caval filter rendering it unremovable has not been published. METHODS: A 66-year-old patient underwent dorsal spondylodesis of the lumbar spine for superinfected metastasis with instability. Because of deep venous thrombosis of both femoral and iliac veins, a caval filter had been placed before surgery. Bone cement from the surgical procedure migrated into the venous bloodstream and got caught in the caval filter, thus rendering the filter unremovable. RESULTS: Surgical removal of the filter was necessary. CONCLUSION: If caval filters are present in patients undergoing surgery involving the use of bone cement, the possibility of cement being caught by the filter must be considered.

Aged↗
PubMed2006

Feasibility of real-time magnetic resonance-guided stent-graft placement in a swine model of descending aortic dissection.

AIMS: To evaluate the pre-clinical feasibility of real-time magnetic resonance imaging (rtMRI) to guide stent-graft placement for experimental aortic dissection (AD) and to alleviate disadvantages of ionising radiation and nephrotoxic contrast media. Endovascular stent-graft placement for thoracic aortic disease is usually performed under X-ray guidance. The feasibility of rtMRI-guided stent-graft placement is currently not known. METHODS AND RESULTS: By using a catheter-based technique, dissections of the descending thoracic aorta were successfully created in eight domestic pigs. Subsequent implantation of commercially available, nitinol-based stent-grafts was performed entirely under rtMRI guidance. By pre-interventional MRI, the mean minimal true-lumen diameter was 0.9 (0.825-0.975) cm. rtMRI permitted not only the successful and safe device navigation within the true lumen from the iliac arteries to the thoracic aorta, but also the precise positioning and deployment of the stent-graft and safe withdrawal of the delivery catheter in seven of eight pigs. This was achieved without any other complications. After the stent-graft placement, MRI demonstrated complete obliteration of the false lumen, which was confirmed at autopsy. All stent-grafts were well expanded resulting in an increase in the size of the true-lumen diameter to 2.05 (1.925-2.1) cm (P=0.066 vs. baseline). CONCLUSION: In experimental AD, rtMRI-guided endovascular stent-graft placement is feasible and safe and has the potential for mitigating radiation and contrast-related side effects. Additionally, it allows not only pre-interventional diagnosis and detailed anatomic diagnosis, but also permits immediate post-interventional, anatomical, and functional delineation of procedure success that may serve as a baseline for future comparison during follow-up.

Aortic Dissection↗
PubMed2006

Endovascular stent-graft treatment of penetrating aortic ulcer: results over a median follow-up of 27 months.

BACKGROUND: Penetrating aortic ulcer (PAU) is increasingly acknowledged as a pathological variant of classic false-lumen aortic dissection with a high incidence of bleeding complications and rupture in up to 40% of patients. The objective of this study was to investigate the results of endovascular stent-graft placement for the treatment of patients with PAUs. METHODS: Between July 1999 and December 2004, endovascular stent-graft repair of PAU was performed in 22 patients (69.1 +/- 7.8 years, 16 men), 3 (14%) of whom had contained aortic rupture. Stent-graft placement was performed in the cardiac catheterization laboratory with the patient under general anesthesia, using a surgical access. RESULTS: Procedural success was achieved in all but 1 patient (technical success rate 96%). Postoperatively, 1 (5%) patient had minor stroke with transient amentia. There were no other inhospital complications or deaths. During a median follow-up of 27 (range 1-62) months, 1 patient underwent adjunctive stent-graft placement for type I endoleak. Three patients died unrelated to the aortic disease late during follow-up. Overall survival rates were 100% at 30 days, 100% at 1 year, 82.5% +/- 11.3% at 2 years, and 61.9% +/- 20.0% at 5 years. CONCLUSIONS: Endovascular stent-graft treatment is an effective treatment for patients with PAU and is associated with low procedural morbidity. Both acute and midterm mortality of this novel treatment concept appear to be favorable compared with the natural course of the disease.

Aged↗
PubMed2006

Percutaneous repair of abdominal aortic pseudoaneurysm by catheter-based delivery of thrombin.

PURPOSE: To present a case in which thrombin was injected percutaneously to treat an aortic pseudoaneurysm. CASE REPORT: A 63-year-old man developed a large pseudoaneurysm in the abdominal aorta after surgical fenestration and patch aortoplasty for acute type B aortic dissection with malperfusion syndrome. Transcatheter delivery of 1500 units of thrombin resulted in complete thrombosis of the pseudoaneurysm sac. No complications occurred. Twelve months after the procedure, the pseudoaneurysm was completely resolved on computed tomography. CONCLUSION: Thrombin continues to prove its safety and efficacy for the treatment of pseudoaneurysms at numerous anatomical sites, including the abdominal aorta.

Aneurysm, False↗
PubMed2006

Whole-body 18F-FDG PET/CT in the presence of truncation artifacts.

UNLABELLED: We investigated the effect of CT truncation in whole-body (WB) PET/CT imaging of large patients, and we evaluated the efficacy of an extended field-of-view (eFOV) correction technique. METHODS: Two uniform phantoms simulating a "torso" and an "arms-up" setup were filled with (18)F-FDG/water. A third, nonuniform "body phantom was prepared with hot and cold lesions. All 3 phantoms were positioned in the center of the PET/CT gantry with >or=10% of their volume extending beyond the maximum CT FOV. An eFOV algorithm was used to estimate complete CT projections from nonlinear extrapolation of the truncated projections. CT-based attenuation correction (CT AC) of the phantom data was performed using CT images reconstructed from truncated and extended projections. For clinical validation, we processed truncated datasets from 10 PET/CT patients with and without eFOV correction. RESULTS: When using truncated CT images for CT AC, PET tracer distribution was suppressed outside the transverse CT FOV in phantom and patient studies. PET activity concentration in the truncated regions was only 10%-32% of the true value but increased to 84%-100% when using the extended CT images for CT AC. At the same time, the contour of phantoms and patients was recovered to the anatomically correct shape from the uncorrected emission images, and the apparent distortion of lesions near the maximum CT FOV was reduced. CONCLUSION: Truncation artifacts in WB PET/CT led to visual and quantitative distortions of the CT and attenuation-corrected PET images in the area of truncation. These artifacts can be corrected to improve the accuracy of PET/CT for diagnosis and therapy response evaluation.

Algorithms↗
PubMed2005

Respiration artifacts in whole-body (18)F-FDG PET/CT studies with combined PET/CT tomographs employing spiral CT technology with 1 to 16 detector rows.

PURPOSE: Co-registration accuracy in combined whole-body (WB) PET/CT imaging is impaired by respiration-induced mismatches between the CT and the PET. Furthermore, PET/CT misregistration may bias the PET tracer distribution following CT-based attenuation correction (CT-AC). With the introduction of multi-row CT technology of up to 16 detector rows into PET/CT designs, we investigated the incidence of respiration artifacts in WB PET/CT examinations of patients who were unable to follow any breath-hold instructions. METHODS: A total of 80 WB studies from six international sites operating PET/CT tomographs with 1-, 2-, 4-, 6-, 8-, and 16-row spiral CT were included. PET/CT examinations were acquired with the patients breathing normally during both the CT and the PET scan, and CT-AC was performed routinely. All studies were anonymized and reviewed independently by three radiologists and three nuclear medicine specialists. We report the frequency and severity of artifacts on CT and PET for the thorax and the abdomen. RESULTS: In WB PET/CT imaging of normally breathing patients, significant gains in diagnostic image quality can be expected from employing CT technology with six or more detector rows. In our study, fewer PET images appear distorted than corresponding CT images, which is due to the limited propagation of only mild CT image artifacts after the resampling of the CT-based attenuation map during CT-AC. CONCLUSION: In whole-body PET/CT imaging of normally breathing patients, respiration-induced artifacts are reduced in both magnitude and prominence for PET/CT systems employing CT components of six or more detector rows.

Adolescent↗
PubMed2005

Liver transplantation for hepatocellular carcinoma in cirrhosis: is clinical tumor classification before transplantation realistic?

BACKGROUND: The decision of whether to proceed with transplantation in patients with hepatocellular carcinoma (HCC) in cirrhosis is based on clinical and imaging findings. The purpose of our study was to evaluate the accuracy of the current system. MATERIALS AND METHODS: We evaluated data of 70 patients with HCC who underwent liver transplantation (LTx) at our center. We specifically analyzed the correlation between preoperative imaging studies and postoperative anatomopathologic findings. Tumor-node-metastasis, Milan, and University of California San Francisco (UCSF) classifications were used. Patients were divided in 2 groups: (1) Patients undergoing live-donor LTx (LDLTx, n=35) and (2) patients undergoing cadaveric LTx (CLTx, n=35). RESULTS: Only 10 (14.3%) of the 70 patients considered had tumor diameter that was correctly identified by pretransplant radiologic examinations. Twenty-four (34.2%) patients had correct identification of the number of tumors present. Fifty (71.4%) patients had incorrect measurements of tumor diameter of more than 1 cm. Sensitivity of radiologic imaging was especially poor for tumors between 1 and 2 cm and less than 1 cm (21% and 0%, respectively). Best accuracy of 60% was found for both the Milan and UCSF criteria. No significant difference was found between the two patient groups concerning the accuracy of the various systems/criteria of classification. CONCLUSIONS: Current imaging techniques have a high incidence of false-negative and false-positive results when evaluating HCC in cirrhosis. A critical appraisal of patient characteristics together with great caution when interpreting imaging studies is recommended to determine candidacy for transplantation.

Carcinoma, Hepatocellular↗
PubMed2005

Endovascular stent-graft treatment of aortic dissection: determinants of post-interventional outcome.

AIMS: To investigate the results of endovascular stent-graft placement for the treatment of patients with type B aortic dissection (B-AD). METHODS AND RESULTS: A total of 38 patients (62+/-10 years, 32 male) with acute (n=10) and chronic (n=28) type B-AD were treated with endovascular stent-grafts. The implantation procedure was successful in all patients. Peri-procedural non-fatal complications occurred in four (11%) patients. Overall, 4/38 (11%) patients died during the in-hospital period. Patients undergoing stent-graft placement for acute AD had a significantly higher in-hospital mortality than patients with chronic AD (40 vs. 0%, P=0.001). During a median follow-up of 18 (1-57) months, there were six additional deaths. Overall survival rates were 97.4+/-2.6% at 30 days, 80.4+/-6.7% at 1 year, 73.2+/-7.8% at 2 years, and 54.9+/-16.9% at 4 years. Patients with a poor clinical health status (ASA class > 3) had a significantly reduced life expectancy compared with patients with only moderate co-morbidities (ASA class </= 3) (1-year survival rate 28.6+/-17.1 vs. 92.6+/-6.7%, P=0.0001). Multivariable analysis revealed that a poor clinical health status (ASA>3) pre-operatively (HR=29.5, 95% CI 1.5-581.9, P=0.026) and increased age (HR=1.1, 95% CI 0.9-1.2, P=0.084) were independent determinants of post-interventional mortality. CONCLUSION: Endovascular stent-graft treatment is a safe alternative for patients with AD. The pre-operative clinical health status of the patient is the most important determinant of post-interventional outcome. Careful patient selection is thus of particular importance.

Acute Disease↗
PubMed2005

Endovascular stent-graft placement for acute and contained rupture of the descending thoracic aorta.

OBJECTIVES: To identify determinants of postinterventional death after endovascular stent-graft placement for acute rupture of the descending thoracic aorta, an emerging therapeutic modality for this highly life-threatening condition. METHODS: Between July 1999 and November 2004, 17 patients (14 males; mean age, 65+/-16 (25-83) years) underwent stent-graft repair of the descending thoracic aorta for acute rupture from a thoracic aneurysm (TAA, n=6), acute aortic dissection (AAD, n=6), penetrating aortic ulcer (PAU, n=3), or blunt chest trauma (n=2). Immediate, 30-day, 1-year, and 3-year mortality was assessed. Twenty-one clinical and procedural variables were evaluated in a post-hoc analysis regarding their influence on mortality. Of these, four preprocedural factors with the greatest impact were used to construct a rupture score with a scale from 0 (no adverse prognostic factors present) to 4 (all four adverse factors present). RESULTS: Stent-graft placement was technically feasible in all patients. Complete exclusion of the ruptured aortic pathology could be achieved in only 11 (65%) patients, despite implantation of 1.6+/-0.9 stent-grafts per patient, with a median length of 130 mm. There was one procedure-related early complication (bleeding at the access site). One patient died immediately following the procedure because of progressive mediastinal hematoma, although the rupture site was effectively sealed. Overall survival rates were (76.5+/-10.3)% at 30 days and (52.9+/-12.1)% at 1 year and remained at (52.9+/-12.1)% at 3 years. The four most important preprocedural denominators of death were (1) TAA or AAD as the underlying etiology of aortic rupture (P=0.024), (2) maximum aortic diameter>5 cm (P=0.024), (3) presence of mediastinal hematoma (P=0.056), and (4) an estimated lesion length requiring >1 stent-graft to be covered (P=0.009). Furthermore, residual leakage at the conclusion of the procedure (P=0.009), postprocedural need for dialysis (P=0.004), and prolonged ventilation (P=0.043) were significantly associated with postprocedural death. Using a threshold of >or=3, the rupture score constructed on the basis of the four preprocedural denominators of death was found to be well suited to discriminate postprocedural death (1-year survival: (20.0+/-12.7)% in patients with a rupture score>or=3 vs. 100% in patients with a rupture score<3, P=0.001). CONCLUSION: Endovascular stent-graft placement in patients with acute aortic rupture was technically feasible, albeit still associated with high mortality. A simple risk score constructed in retrospect, on the basis of preprocedural prognostic factors, appeared to provide a useful separation of candidates who are likely to benefit from a straightforward endovascular procedure and should be tested prospectively in future studies.

Acute Disease↗
PubMed2004

Unknown primary tumors: detection with dual-modality PET/CT--initial experience.

PURPOSE: To retrospectively evaluate fused positron emission tomography (PET)/computed tomography (CT) in depicting the primary lesion in cancer of an unknown primary tumor, compared with PET, CT, and PET and CT side-by-side evaluation. MATERIALS AND METHODS: Institutional review board approval and informed consent were obtained. Forty-five patients (26 men and 19 women) with metastatic cervical adenopathy (n = 18) or extracervical metastases (n = 27) of unknown primary tumor were included. The mean age of the patients was 57 years (range, 29-95 years). PET/CT imaging was performed in all patients 1 hour after administration of 350 MBq of fluorodeoxyglucose with a whole-body field of view. Contrast agents were administered orally and intravenously in all patients to ensure diagnostic CT data. PET/CT data sets were evaluated for the primary tumor, and imaging results were compared with those of CT, PET, and PET and CT side-by-side evaluation. Differences in diagnostic performance were assessed by using the McNemar test with Bonferroni correction, which accounts for multiple comparisons. RESULTS: PET/CT depicted the primary tumor in 15 (33%) of 45 patients. In 30 (67%) patients, the primary tumor site remained occult (P > .05). PET and CT side-by-side evaluation depicted 13 (29%) of 45 tumors (P > .05). PET alone revealed the primary tumor in 11 (24%) of 45 patients (P > .05), while CT alone helped in the correct diagnosis in eight (18%) of 45 patients (P > .05). There were no significant differences between the diagnostic accuracies of PET/CT and the other imaging modalities. CONCLUSION: PET/CT was able to depict more primary tumors, though not significantly, than either of the other imaging modalities, but larger patient cohorts are required to finally judge its value for revealing the primary tumor site.

Adult↗
PubMed2004

Coronary artery calcium score: influence of reconstruction interval at 16-detector row CT with retrospective electrocardiographic gating.

In 30 patients, Agatston and volumetric scores were assessed by using retrospectively gated multi-detector row computed tomography (CT). For each patient, 10 data sets were created at different times and were evenly spaced throughout the cardiac cycle. For each reconstruction, patients were assigned a percentile that described the level of cardiovascular risk. Nineteen (63%) of 30 patients could be assigned to more than one risk group depending on the reconstruction interval used. Agatston and volumetric scores both proved highly dependent on the reconstruction interval used (coefficient of variation, < or =63.1%) even with the most advanced CT scanners. Accurate and reproducible quantification of coronary calcium seems to require analysis of multiple reconstructions.

Adult↗
PubMed2004

Noninvasive visualization of coronary artery bypass grafts using 16-detector row computed tomography.

OBJECTIVES: The aim of this study was to evaluate the diagnostic accuracy of a 16-detector row computed tomography (CT) scanner for the assessment of coronary artery bypass grafts. BACKGROUND: A new generation of multislice spiral CT scanners, equipped with more and thinner detector rows, allows for reliable noninvasive detection of obstructive coronary artery disease. METHODS: The study included 51 consecutive patients. Three patients had to be excluded from the study due to arrhythmias or fast heart rates despite beta-blockade. A total of 48 patients with 131 coronary artery bypass grafts (internal mammary artery, n = 40; venous grafts, n = 91) were examined by computed tomography angiography (CTA) and by invasive coronary angiography (ICA) using a 16-detector row CT scanner. For cardiac protocols, only the 12 inner detector rings are applied. All CT examinations were performed with retrospective electrocardiogram gating at a mean heart rate of 64 +/- 5 beats/min; 120 ml of Xenetix 300 (Guerbert GmbH, Sulzbach, Germany) were continuously injected. The bypass graft patency and the presence of stenoses as well as the proximal and distal anastomoses were evaluated by two experienced readers. RESULTS: All bypass grafts and 74% of the distal bypass anastomoses could be visualized by CTA; 21 bypass graft occlusions and 1 significant stenosis were detected by CTA and confirmed by ICA. Five false positive and one false negative finding resulted in a sensitivity of 96%, a specificity of 95%, a positive predictive value of 81%, and a negative predictive value of 99%. CONCLUSIONS: Sixteen-detector row CT scanner technology allows for the reliable visualization of coronary bypass grafts. Dysfunctional bypass grafts can be detected with high diagnostic accuracy. This technology can be used as a noninvasive test for patients with suspected graft dysfunction.

Aged↗
PubMed2004

Importance of adrenal incidentaloma in patients with a history of malignancy.

BACKGROUND: Adrenal incidentaloma presents a frequent finding in patients with a history of malignancy. This study was carried out to determine whether imaging techniques can discriminate between a malignant and a benign adrenal tumor and subsequently select candidates for adrenal surgery. METHODS: Beginning in July 1995, oncologic patients with adrenal incidentaloma underwent abdominal ultrasonography, computed tomography (CT), magnetic resonance imaging (MRI), and [ 18 ]fluoro-2-deoxy-D-glucose positron emission tomography (18-FDG-PET). Consecutively in all patients adrenalectomy was performed. Histologic findings were compared with the imaging results. RESULTS: In 42 patients, 33 to 79 years old (mean age, 58 years), 44 adrenal lesions were detectable. Two patients presented with bilateral adrenal masses. At operation, 43 adrenal resections and 3 biopsies were performed. Histologic examination revealed 31 metastases (71%) and 13 adrenal adenomas (29%). In metastases the sensitivity of ultrasonography, CT, MRI, and 18-FDG-PET was 66%, 81%, 100%, and 100%, respectively. For adrenal adenoma, the sensitivity of ultrasonography, CT, MRI, and 18-FDG-PET was 46%, 39%, 100%, and 54%, respectively. CONCLUSIONS: In oncologic patients with indeterminate adrenal tumors MRI and 18-FDG-PET provide accurate differentiation between metastases and benign adenomas. Positive results of these 2 imaging modalities are highly suggestive for metastatic disease. In cases of negative MRI and 18-FDG-PET results the adrenal lesion corresponds to a benign adenoma that needs no surgical intervention.

Adenoma↗
PubMed2002

Right-lobe living related liver transplantation: evaluation of a comprehensive magnetic resonance imaging protocol for assessing potential donors.

The purpose of this study was to determine the practicability and diagnostic accuracy of a magnetic resonance (MR) protocol capable of replacing computed tomography, catheter angiography, and endoscopic retrograde cholangiopancreatography for the presurgical evaluation of potential liver donors before right hepatectomy. MR imaging (MRI) was performed on a 1.5 T scanner using a phased-array torso surface coil for signal reception. The following image sets were collected: axial two-dimensional (2D) T1-weighted fast low angle shot (FLASH), axial 2D T2-weighted half-Fourier acquisition single-shot turbo-spin-echo (HASTE) with fat saturation, coronal MR cholangio-pancreatography (MRCP) based on 2D multisection HASTE and single-section single-shot rapid acquisition with relaxation enhancement (RARE) imaging, dynamic contrast-enhanced three-dimensional (3D) FLASH, and contrast-enhanced T1-weighted FLASH. 3D FLASH data sets were collected before and after an intravenous administration of Multihance (gadobenate dimeglumine, Gd-BOPTA; Bracco, Milano, Italy), 0.2 mmol/kg of body weight. Thirty-eight potential liver donors were assessed by means of MRI. Twenty patients also underwent digital subtraction angiography (DSA). Of these, 16 patients underwent liver harvesting. MR angiography (MRA) data sets correlated with DSA results, and MRCP results correlated with intraoperative findings. Patients were excluded as potential donors based on insufficient liver mass of the left hepatic lobe (n = 5) or presence of hepatic pathological states (n = 9) seen at MRI, such as hemangiomas, focal nodular hyperplasias, or hepatic steatosis. MRCP showed the biliary system to the level of the first hepatic side branch. Dilated ducts were present in 4 patients. MRA depiction of hepatic arterial morphological characteristics correlated with catheter angiography results in all 20 patients: Three left hepatic arteries originating from the left gastric artery, three aberrant right hepatic arteries originating from the superior mesenteric artery, and two aberrant origins of both hepatic arteries and one common hepatic artery originating from the superior mesenteric artery were correctly identified on MRA. Similarly, the portal venous system was fully assessed on MRA. A comprehensive assessment of the hepatic parenchyma, biliary and pancreatic ductal system, and hepatic arterial, portal, and venous systems can be accomplished using the outlined protocol.

Adult↗
PubMedDate not supplied

Positron emission tomography/computed tomography--imaging protocols, artifacts, and pitfalls.

There has been a longstanding interest in fused images of anatomical information, such as that provided by computed tomography (CT) or magnetic resonance imaging (MRI) systems, with biological information obtainable by positron emission tomography (PET). The near-simultaneous data acquisition in a fixed combination of a PET and a CT scanner in a combined PET/CT imaging system minimizes spatial and temporal mismatches between the modalities by eliminating the need to move the patient in between exams. In addition, using the fast CT scan for PET attenuation correction, the duration of the examination is significantly reduced compared to standalone PET imaging with standard rod-transmission sources. The main source of artifacts arises from the use of the CT-data for scatter and attenuation correction of the PET images. Today, CT reconstruction algorithms cannot account for the presence of metal implants, such as dental fillings or prostheses, properly, thus resulting in streak artifacts, which are propagated into the PET image by the attenuation correction. The transformation of attenuation coefficients at X-ray energies to those at 511 keV works well for soft tissues, bone, and air, but again is insufficient for dense CT contrast agents, such as iodine or barium. Finally, mismatches, for example, due to uncoordinated respiration result in incorrect attenuation-corrected PET images. These artifacts, however, can be minimized or avoided prospectively by careful acquisition protocol considerations. In doubt, the uncorrected images almost always allow discrimination between true and artificial finding. PET/CT has to be integrated into the diagnostic workflow for harvesting the full potential of the new modality. In particular, the diagnostic power of both, the CT and the PET within the combination must not be underestimated. By combining multiple diagnostic studies within a single examination, significant logistic advantages can be expected if the combined PET/CT examination is to replace separate state-of-the-art PET and CT exams, thus resulting in significantly accelerated diagnostics.

Humans↗
PubMedDate not supplied

Hemangioendothelioma of the liver associated with a solitary extrahepatic lesion.

Epithelioid hemangioendothelioma of the liver is very uncommon and is quite difficult to distinguish from a cholangiocarcinoma or a metastatic liver disease by imaging diagnostics. However, the histological features are characteristic for this soft-tissue tumor. Although liver tumor is usually multifocal and a liver resection is not possible in most cases, we report a case of a multifocal epithelioid hemangioendothelioma of the liver that was completely resected. The tumor was associated with a solitary extrahepatic lesion, which was first discovered six months after the liver resection and which was also resected.

Adult↗