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H B Gehl

Publications and source records attributed to H B Gehl.

At least 19 recordsLinked to original sources
PubMed2004

Renal perfusion imaging using contrast-enhanced phase-inversion ultrasound.

AIMS: We evaluated different techniques of contrast-enhanced phase-inversion ultrasound to visualize renal perfusion in native kidneys and kidney transplants. MATERIALS AND METHODS: Contrast-enhanced phase inversion ultrasound with different levels of mechanical index and frame rate was performed in 20 kidneys of 13 healthy volunteers. In addition, five dysfunctioning kidneys of patients with chronic renal failure, five functionally intact kidney transplants, three kidney transplants with compensated renal failure, and two kidney transplants with acute rejection were studied. Analysis using a software algorithm for time-resolved perfusion imaging was compared to single-image analysis performed by three independent radiologists. RESULTS: Optimal depiction of renal perfusion was achieved only by using a mechanical index, which was high enough to destroy the microbubbles of the contrast agent (burst imaging) combined with a low frame rate (0.5 images/second). Renal cortex and medulla showed a homogeneous enhancement in kidneys of healthy volunteers and functionally intact renal transplants. Dysfunctioning kidneys of patients with chronic renal failure as well as kidney transplants with compensated renal failure or acute rejection showed a significantly reduced level of enhancement. Computer-assisted time-resolved perfusion analysis was not superior to single-image analysis. CONCLUSION: Renal perfusion patterns of normal and abnormal tissue can be visualized using contrast-enhanced phase-inversion ultrasound imaging.

Adult↗
PubMed2003

Changes of fascia and muscles before and 12 months after successful treatment of recalcitrant venous leg ulcers by shave therapy.

BACKGROUND: In chronic venous insufficiency (CVI) III typical changes of skin, subcutaneous tissue, fascia and muscle can be found. It was believed, that the thickening of the fascia is irreversible and it has been postulated that the degeneration of muscles is causative for the persistence of recalcitrant leg ulcers. PATIENTS AND METHODS: By computed tomography (CT) and magnetic resonance imaging (MRI) 8 patients with therapy resistant venous ulcers were examined. Changes of fascia and muscles were determined preoperatively and 12 months after successful shave therapy. RESULTS: By CT a thinning of the preoperatively thickened fascia could be demonstrated in all patients one year after surgery. Before shave therapy MRI showed that the fascia was not only thickened and blurred, but also had fluid accumulations perifascial. 12 months after therapy the fascia was thinner and sharply demarcated. The fluid was either absent or distinctively reduced. Referring to the thickness of fascia an average decrease of 0.084 cm (0.03-0.17 cm) was observed. Before surgery the muscles showed a fatty degeneration as a sign of atrophy; with CT and MRI no changes could be demonstrated after one year in all patients. CONCLUSION: The results after one year demonstrate for the first time, that the changes of the fascia in CVI III are reversible and that there is no direct correlation between the degeneration of muscles and the persistence of venous leg ulcers.

Aged↗
PubMed2001

Off-site evaluation of liver lesion detection by Gd-BOPTA-enhanced MR imaging.

The aim of this study was to determine the efficacy of Gd-BOPTA-enhanced MRI in liver lesion detection in comparison with unenhanced MRI and dynamic CT. The image sets of 148 of 151 patients enrolled in a multicenter German phase-III trial were evaluated by two independent radiologists unaffiliated with the investigating centers. Patients underwent a routine MRI protocol comprising T2- and T1-weighted spin-echo and T1-weighted gradient-echo (GE) sequences pre and 1 h post 0.1 mmol/kg Gd-BOPTA (Bracco-Byk Gulden, Konstanz, Germany). Additionally, a serial T1-weighted GE scan was performed after administration of the first half of the dose. All patients underwent dynamic contrast-enhanced CT. The evaluation was performed with regard to the number and size of lesions detected per patient by each modality or sequence. Furthermore, all pre CM and pre + post CM image sets were analyzed for number of lesions per patient. Both readers detected significantly more lesions in the contrast-enhanced image set compared with the unenhanced image set (32 and 39 %, respectively; p < 0.0001). While contrast-enhanced CT detected a similar number of lesions to unenhanced MRI, it was clearly inferior to contrast-enhanced MRI (reader 1: p = 0.0117; reader 2: p = 0.0225). Of the T1-weighted scans performed, the dynamic and late T1-weighted GE exams contributed most to the increased lesion detection rate (reader 1: p = 0.0007; reader 2: p = 0.0037). The size of the smallest lesion detected by means of MRI was significantly larger in the pre-CM image sets than in the pre + post CM image sets (reader 1: p = 0.001; reader 2: p < 0.0001). Gd-BOPTA-enhanced MRI detected significantly smaller lesions than contrast-enhanced CT (reader 1: p = 0.0117; reader 2: p = 0.0925). Gd-BOPTA-enhanced MR imaging improves liver lesion detection significantly over unenhanced MRI and dynamic CT.

Adult↗
PubMed2001

Enhancement of cerebral diseases: how much contrast agent is enough? Comparison of 0.1, 0.2, and 0.3 mmol/kg gadoteridol at 0.2 T with 0.1 mmol/kg gadoteridol at 1.5 T.

RATIONALE AND OBJECTIVES: To determine the clinical dose of gadoteridol (ProHance, Bracco-Byk Gulden) to use for the assessment of blood-brain barrier breakdown on low-field magnetic resonance (MR) scanners that corresponds to a standard dose of gadoteridol on high-field MR scanners. METHODS: This prospective study was carried out at four centers. A total of 138 patients with suspected or known brain diseases underwent a routine head scan comprising precontrast T2-weighted turbo spin-echo and T1-weighted spin-echo sequences on a 1.5-T MR scanner. After administration of a standard dose of 0.1 mmol/kg gadoteridol, the T1-weighted scan was repeated after a delay of 15 to 20 minutes. For continuing the examination on a 0.2-T MR scanner (Magnetom OPEN, Siemens), a standard-dose T1 spin-echo sequence was started within 30 to 50 minutes of the first injection. Then two additional T1-weighted low-field sequences were each started 5 minutes after two additional doses of 0.1 mmol/kg gadoteridol. Eighty patients with enhancing lesions underwent an intraindividual comparison. Evaluation of the overall numbers of lesions detected and of lesion size and character was performed on-site as well as off-site by two independent readers. RESULTS: The single-dose, low-field sequence detected significantly fewer enhancing lesions (80/95 lesions; P < 0.05), particularly metastases and infarctions, than did the standard-dose, high-field sequence. No statistically relevant differences (reader 1: P = 1; reader 2: P = 0.8) were found between the double- and triple-dose, low-field sequences and the standard-dose, high-field sequence. Primary brain tumors were detected by all postcontrast sequences irrespective of the dose. CONCLUSIONS: At low field, the clinically equivalent dose to 0.1 mmol/kg gadoteridol at high field is 0.2 mmol/kg. A dose of 0.1 mmol/kg gadoteridol is less effective and cannot be recommended for use on extremely low-field scanners.

Adult↗
PubMed2001

Anatomical accuracy in medical 3D modeling.

In complex surgery, medical modeling has become an accepted tool for diagnosis, simulation and the planning of surgical interventions [1]. However, the question concerning the accuracy of the model, i.e. the equivalence between the model itself on the one hand and the original anatomical situation on the other hand, remains unanswererd in the current literature.

Cephalometry↗
PubMed1999

Acquired thromboatheromatous coarctation of the aorta: acquired coarctation of the aorta.

BACKGROUND: Atheromatosis of the thoracic aorta and aortic arch is a well established source of systemic embolism. Acquired atheromatous coarctation of the aortic arch is a rare finding and not well documentated so far. CASE REPORT AND FINDINGS: Two patients presenting with intermittent claudication of the lower extremities were identified as having thromboatheromatous coarctation of the aortic arch as visualized by magnetic resonance tomography, fast CT scan, transesophageal echocardiography, cardiac catheterization and aortography. All findings including invasive hemodynamics resembled congenital coarctation of the aorta. One patient was treated surgically, while the other refused surgery and received long-term anticoagulation. CONCLUSION: Atheromatosis of the thoracic aorta and aortic arch not only cause systemic embolism, but may lead to the clinical and hemodynamic picture of coarctation of the aortic arch.

Aged↗
PubMed1999

Results of a prospective multicenter study for evaluation of the diagnostic quality of an open whole-body low-field MRI unit. A comparison with high-field MRI measured by the applicable gold standard.

OBJECTIVE: To evaluate the diagnostic quality of an open whole-body low-field MRI scanner compared to high-field scanners. MATERIALS AND METHODS: Over a period of 3 months, 401 patients with diseases of the kidney (n = 78), the shoulder (n = 122), the spine (n = 105) and the cerebrum (n = 96) were prospectively evaluated in four participating centers. They all underwent clinical evaluation, low-field and high-field MRI examination and surgical or follow-up confirmation of diagnosis. Clinical, histopathologic, high-field and low-field MRI diagnoses were recorded in standardized questionnaires that were centrally evaluated. Statistical evaluation comprised two parts: ROC analysis assessed accuracy of MRI and clinical diagnoses; furthermore rates of concordance of high- and low-field MRI diagnosis were calculated. RESULTS: We found no statistically relevant difference in high-field MRI diagnosis compared to low-field MRI diagnostic accuracy measured by clinical or surgical gold standard in three of the four regions examined; in cerebral examinations there was a small yet significant advantage for the high-field systems (P = 0.01). CONCLUSION: We conclude that the open low-field scanner we evaluated using clinical and surgical gold standard as reference is able to achieve comparable diagnostic accuracy compared to high-field scanners at lower costs and greater patient comfort. Limitations due to field strength (signal-to-noise ratio, resolution, scan time) seem to be relevant only in a very small number of cases that warrant high-field examination.

Adult↗
PubMed1999

Familial pontocerebellar hypoplasia type I with anterior horn cell disease.

We report the association of pontocerebellar hypoplasia and anterior horn cell disease in three female siblings. One child presented with the classical clinical and neuropathological features of pontocerebellar hypoplasia with associated anterior horn cell disease, described by Barth as pontocerebellar hypoplasia type I. This patient showed polyhydramnios, congenital contractures, respiratory insufficiency, hypotonia, areflexia, listlessness and myoclonic seizures. Postmortem examination revealed a loss of neurons and reactive gliosis in the pontocerebellum and in addition anterior horn cell atrophy resembling Werdnig-Hoffmann disease. Another sibling demonstrated the same clinical symptoms. However neuropathological findings showed evidence for pontocerebellar hypoplasia only. The third sibling was examined after induced fetal abortion because of prenatally diagnosed arthrogryposis. Anterior horn cell disease was obvious histologically whereas pontocerebellar hypoplasia could not be demonstrated due to cerebral autolysis. The similar clinical and neuropathological findings in the three reported siblings suggest a common genetic defect with different patterns of pontocerebellar hypoplasia and associated anterior horn cell disease. The gene defect of this rare disorder is still unknown. The 'survival motor neuron' gene of spinal muscular atrophy was not found in these three siblings.

Abnormalities, Multiple↗
PubMed1999

Ferric ammonium citrate as a positive bowel contrast agent for MR imaging of the upper abdomen. Safety and diagnostic efficacy.

PURPOSE: To evaluate the safety and diagnostic efficacy of two different doses of ferric ammonium citrate as a paramagnetic oral contrast agent for MR imaging of the upper abdomen. MATERIAL AND METHODS: Ninety-nine adult patients referred for MR imaging for a known or suspected upper abdominal pathology were included in this randomized multicenter double-blind clinical trial. Imaging was performed with spin-echo (T1- and T2-weighted) and gradient-echo (T1-weighted) techniques before and after administration of either 1200 mg or 2400 mg of ferric ammonium citrate dissolved in 600 ml of water. Safety analysis included monitoring of vital signs, assessment of adverse events, and laboratory testing. Efficacy with regard to organ distension, contrast distribution, bowel enhancement and delineation of adjacent structures was graded qualitatively. RESULTS: No serious adverse events were reported for either of the two concentrations. A total of 31 minor side effects were noted, of which significantly more occurred in the higher dose group (p<0.01). The diagnostic confidence in defining or excluding disease was graded as better after contrast administration for 48% of all images. Marked or moderate enhancement of the upper gastrointestinal tract was achieved at both doses in 69.5% of cases with no evident difference between the two doses. The higher dose tended to show better results in terms of the contrast assessment parameters. CONCLUSION: Ferric ammonium citrate is a safe and effective oral contrast agent for MR imaging of the upper abdomen at two different dose levels. The higher dose showed a tendency toward better imaging results while the lower dose caused significantly fewer side effects. Therefore the 1200 mg dose can be recommended in view of the risk-to-benefit ratio.

Abdomen↗
PubMed1998

[MRI-controlled biopsies].

Biopsies were the first "intervention" under MR guidance. After initial difficulties concerning ferromagnetic biopsy instruments and the design of MR scanners, the latest technological improvements rendered MR guidance for biopsies more feasible. In this article we illustrate present-day clinical experience in the field of abdominal, breast and bone biopsy. Important aspects regarding the different designs of "interventional" MR scanners and the visualization of instruments for biopsy are discussed.

Abdomen↗
PubMed1998

Shave therapy is a simple, effective treatment of persistent venous leg ulcers.

BACKGROUND: Leg ulcers in deep venous insufficiency, especially the postthrombotic type, are often resistant to therapy. OBJECTIVE: The purpose of this study was to evaluate short-term and long-term effects of shave therapy in persistent or recurrent venous ulcers. METHODS: From January 1994 to October 1997, 80 patients with 105 chronic leg ulcers were treated by shave therapy. This method involved removing ulcers together with the surrounding lipodermatosclerosis and covering the wounds with meshed split-skin graft. Fifty-nine patients with 76 ulcers were examined after 3 months for assessment of short-term results. The first 18 patients with 26 ulcers from the years 1994 and 1995 were evaluated for long-term results. RESULTS: The short-term healing rate after 3 months in 59 patients was 79%. Of 8 patients from 1995 (follow-up period, 1 year and 8 months), 7 patients had complete healing and 1 patient had a small ulcer. Of 10 patients from 1994 (average follow-up period, 2 years and 8 months), 8 patients had complete healing and 2 patients showed small superficial ulcerations within the transplanted areas. From these results, a long-term healing rate of 88% was calculated in 18 patients. Two of the 3 patients with recurrences had stopped compression therapy after good short-term results. CONCLUSION: For patients with recalcitrant leg ulcers in deep venous insufficiency and/or postthrombosis, shave therapy is a simple, quick, and effective surgical method with favorable short-term and long-term results.

Adult↗
PubMed1998

[Comparative magnetic resonance imaging of renal space-occupying lesions with a high and low field MRI system].

PURPOSE: A prospective study of the diagnostic accuracy and image quality of two MRI systems in the detection of renal tumors was investigated. MATERIALS AND METHODS: 34 patients with the clinical suspicion of a space-occupying renal lesion were examined by MRI with a low field (0.2 Tesla magnet) and a high field (1.5 Tesla magnet) for comparison. An "informed" and a "blind" observer evaluated all of the MR images. In addition, the signal-to-noise and contrast-to-noise ratios were evaluated as second quality parameters. RESULTS: In 29 cases the results could be compared with a confirmed release diagnosis. Diagnostic accuracy was comparable with both systems (Sensitivity for both observer on LF apparatus: 83%, HF apparatus: 81%) although the signal-to-noise and contrast-to-noise ratios were significantly poorer at low field. CONCLUSIONS: The low field system in comparable to the high field MRI for detection and differentiation of renal space-occupying lesions.

Diagnostic Errors↗
PubMed1997

Overview of MnDPDP as a pancreas-specific contrast agent for MR imaging.

PURPOSE: To describe and discuss previous and ongoing clinical and experimental studies with MnDPDP (Teslascan) as a pancreas-specific contrast agent for MR imaging. MATERIAL AND METHODS: All results, both experimental and clinical, applying MnDPDP as a pancreas-specific contrast agent for MR imaging, were collected. RESULTS: An increase of up to 100% in signal intensity was seen in normal pancreatic parenchyma, reaching its maximum approximately 25 min after the beginning of MnDPDP administration. Maximal enhancement was sustained for 4 h. Enhancement was only seen in the T1-weighted images. No enhancement was observed in tumours and an increase in contrast-to-noise of about 200% was obtained. The uptake of MnDPDP in pancreatitis compared with normal pancreatic parenchyma was decreased in an animal model. CONCLUSION: Improved depiction and demarcation of pancreatic tumours with MR imaging were obtained after administration of MnDPDP. MR imaging with and without MnDPDP might be valuable for staging of pancreatitis.

Acute Disease↗
PubMed1996

Fetal intracerebral hemorrhage in the second trimester: diagnosis by sonography and magnetic resonance imaging.

Germinal matrix intraventricular hemorrhage has rarely been observed in the fetus. In most cases the etiology is clear. We report one case of prenatal diagnosis of a periventricular hemorrhage of uncertain etiology in a fetus of 22 weeks' gestation. For confirmation of the ultrasound diagnosis, antenatal magnetic imaging was performed. A male child was delivered in good condition at 37 weeks by Cesarean section. Postnatal ultrasound examination showed a cystic lesion in the right frontal lobe (10 x 10 mm) connecting with the right lateral ventricle. The development of the child at 18 months of age has been normal without any neurological impairment.

Adult↗
PubMed1996

[Technique of MRT-guided core biopsy in the abdomen using an open low-field scanner: feasibility and initial clinical results].

PURPOSE: Due to high soft-tissue contrast and multiplanar imaging capabilities MRI is an interesting modality to perform image-guided biopsies. We checked on the feasibility of MR-guided core biopsies of abdominal masses with an open low-field scanner (0.2 Tesla; vertical field axis). METHODS: 9 patients underwent MR-guided biopsies of abdominal target lesions (6 focal liver lesions, two adrenal masses, one pelvic mass). Different MR-compatible core biopsy instruments were used (needle diameters 14G-18G). MR scans during the procedures were obtained applying T1-weighted gradient echo sequences suitable for breath-hold imaging. RESULTS: In each case, needle guidance was reliable, so that the biopsy instrument could be positioned correctly. Multiplanar imaging capabilities enabled even angled approaches to upper abdominal masses to be realized safely. The combination of magnet design and table design offered suitable access to the patient. CONCLUSION: Using an open low-field scanner, MR-guided core biopsies of abdominal masses are practicable.

Abdomen↗
PubMed1996

[A technic of MRT-guided abdominal drainage with an open low-field magnet. Its feasibility and the initial results].

PURPOSE: To test the practicality of MRT-aided drainage using an open low-field magnet and to report on the early clinical results. METHODS: So far seven patients have been treated (four subphrenic abscesses, two psoas abscesses and one pancreatic pseudocyst). The planning of the approach and catheter insertion were carried out under MRT control (Magnetom Open, 0.2 T). Subsequent treatment was controlled by CT and fluoroscopy. Initial puncture was carried out with a non-magnetic 18 gauge Chiba needle. The drainage catheter was introduced by Seldinger's technique in six cases and with a trocar in one patient. RESULTS: In all seven patients drainage could be started successfully. The design of the magnet and coils permitted adequate accessibility of the patient. There were no problems in visualising the puncture needle. Controlling the position of the catheter by MRT was, however, difficult. CONCLUSION: The first two steps in abscess drainage (planning the approach and inserting the catheter) can be carried out under MRT control. For further catheter control and observing the course of the disease we presently prefer CT or fluoroscopy.

Abdomen↗