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Biomedical subjects

S H Duda

Publications and source records attributed to S H Duda.

At least 91 records · Page 5Linked to original sources
PubMed1994

Localized MR 1H spectroscopy reveals alterations of susceptibility in bone marrow with hemosiderosis.

A noninvasive investigation of the structure of hemopoietic bone marrow is based on the determination of the magnetic field distribution within small volume elements in vertebral bodies by localized 1H MR spectroscopy. In patients with hematological diseases the status of the bone marrow was found to considerably influence the homogeneity of the magnetic field in trabecular bone in vivo. The line widths of the 1H signals were evaluated in follow-up studies during initial chemotherapy of eight patients with leukemia. Intraindividual comparison revealed significant broadening of the field distribution after a few weeks of cytotoxic treatment in five of the patients. Additionally, 19 patients after bone marrow transplantation showed significantly broader field distributions in the lipid signals than 13 matched healthy volunteers. These alterations of the microscopic field homogeneity were not caused by trabecular density effects. Iliac crest biopsies revealed high amounts of hemosiderin in the cases with broadened line widths. Ten of the 19 patients after bone marrow transplantation showed high amounts of hemosiderin and broad lines in the spectra. The content of hemosiderin of the other patients was not significantly increased.

Acute Disease↗
PubMed1994

Adenosine antagonist theophylline prevents the reduction of glomerular filtration rate after contrast media application.

Radiographic contrast media (CM) can induce renal failure and this may serve as an experimental model of acute renal failure (ARF). One vasoactive factor likely to be involved in ARF is adenosine. In a double-blind, placebo-controlled study we investigated the effect of theophylline (TP), an adenosine receptor antagonist, regarding changes in renal hemodynamics induced by CM. Thirty-nine patients who received 100 ml of a non-ionic low osmolar CM (iopromide) were studied for changes in GFR and RPF by continuous inulin and PAH clearance before and until four hours after CM application. Forty-five minutes before the application of CM, patients were randomized and received either theophylline (5 mg/kg body wt) or the vehicle and placebo (saline) intravenously in a blinded manner. We additionally measured the creatinine clearance on the day before and two days after CM application. Sodium excretion, N-acetyl-beta-glucosaminidase (NAG) excretion, plasma renin activity (PRA) and aldosterone levels were also measured before and after CM application. Theophylline levels were within the therapeutic range in patients of the theophylline group during and four hours after CM application (59.0 +/- 10.6 mumol/liter and 40.1 +/- 10.9 mumol/liter). GFR, measured by inulin clearance significantly declined under CM application in patients without TP application (N = 19; 88 +/- 40 to 75 +/- 32 ml/min/1.72 m2; P < 0.01). In the group of patients receiving theophylline (N = 18) the GFR remained constant (75 +/- 26 vs. 78 +/- 33 ml/min/1.72 m2).(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Kidney Injury↗
PubMed1994

[The MR tomography of focal liver lesions with the superparamagnetic contrast agent AMI-25 at 1.5 tesla].

Superparamagnetic iron oxide particles (AMI-25) were evaluated as a liver contrast agent in high-field MR imaging (1.5 T). 16 patients with up to 5 presumed focal liver lesions (liver metastases n = 8, HCC n = 5, Klatskin tumours n = 2, FNH n = 1) received 15 mumol Fe/kg BW intravenously and were examined via standard T1- and T2-weighted spin-echo sequences. Quantitative image analysis showed a post-contrast increase of the contrast-to-noise ratio (C/N) from 1.6 to 7.4 on SE 2,500/15 images (p < .05). However, C/N was in the same range on plain SE 2,500/90 scans. Blind evaluation by two independent readers revealed that AMI-25-enhanced images did not provide a significantly increased number of lesions. Two patients reported minor, self-limited side-effects (flush, back pain). We conclude that in contrast to reports at mid-field MR imagers, the use of AMI-25 at 1.5 T does not significantly improve the detection of focal liver lesions on conventional SE images.

Adult↗
PubMed1994

[Peripheral pulsed laser angioplasty--4-year clinical experience].

In 134 patients, 21 iliac, 91 femoropopliteal and 22 crural arterial occlusions were treated by percutaneous laser-assisted angioplasty and in 32 patients femoropopliteal occlusions by conventional balloon angioplasty. Laser angioplasty could be performed in 126 patients following initial guide wire recanalisation using 9.7 and 4.5-F multifiber catheters, respectively. In 72 patients a 308-nm excimer laser and in 54 patients a 504-nm pulsed day laser was used. Luminal opening by laser angioplasty was obtained in 102 of 126 (81%) procedures (9 incomplete catheter passages, 15 persistent occlusions). 95% of iliac, 90% of femoropopliteal and 77% of crural recanalizations including supplemental balloon dilatations (n = 105) and stent implantations (n = 24) succeeded technically. Clinical success rates at 1 (2) years after angioplasty were 95% (89%) for iliac, 66% (63%) for femoropopliteal and 57% (50%) for crural treatments. Technical and clinical results of laser-assisted femoropopliteal recanalizations showed no significant differences in comparison to the results of conventional balloon angioplasty. The use of pulsed lasers for the treatment of peripheral arterial occlusive disease would require further technical improvements.

Adult↗
PubMed1994

[CT-guided percutaneous lumbar sympathicolysis in peripheral arterial occlusive diseases].

Between June 1991 and November 1992, 36 patients with peripheral arterial occlusive disease were treated by CT-guided percutaneous lumbar sympathicolysis. Three months after the procedure, 39% claimed subjective improvement, 53% were unchanged and 8% were worse. Walking distance increased significantly from 86 to 167 m (p = 0.02). There was a comparable increase in walking distance between diabetics and non-diabetics. Comparison of one and two level procedures (each 50%) also showed similar increase in walking distance. There were no serious complications. The results justify the use of CT-guided percutaneous lumbar sympathicolysis in patients with peripheral arterial occlusive disease who are unsuitable for treatment by revascularisation. The procedure can be carried out on an outpatient basis and on otherwise inoperable patients and therefore has significant advantages compared with surgical sympathectomy.

Adult↗
PubMed1994

[Transvenous sonography of the peripheral arterial vessels. The initial clinical results].

Intravascular ultrasound with 20 MHz/6.2-French transducer systems was used for arterial imaging via a transvenous approach. In 20 patients suffering from chronic arterial occlusive disease, 15 iliac arteries were evaluated during diagnostic angiography and 5 femoropopliteal arteries during balloon angioplasty (n = 3) and laser-assisted angioplasty (n = 2), respectively. Transvenous sonography did not allow differentiation of arterial wall layers and determination of vessel diameters as is usually possible during intraarterial sonography. Visualisation of iliac arteries was incomplete. In femoropopliteal vessels, guide wires could be detected within the arterial lumen but not in complete occlusions. Delivery of pulsed laser energy induced bright echoes near the catheter tip within a distance of 1-2 cm. Transvenous sonography is insufficient for monitoring of peripheral angioplasty; however, improved imaging quality might be possible at lower frequencies.

Aged↗
PubMed1994

[The chemoembolization of hepatocellular carcinoma: the computed tomographic findings and clinical results in prospective repetitive therapy].

Between April 1989 and March 1993 162 transarterial chemoembolizations (TACE) were performed repeatedly (mean interval: 2.9 months) in 52 patients with hepatocellular carcinoma (HCC): An emulsion of Lipiodol and epirubicin was injected as selectively as possible in a dosage proportional to liver function and tumour size. Before and after each TACE the size of tumours and ratio of tumour volume containing Lipiodol (RTVCL) were determined in CT and the grade of tumour vascularisation was assessed angiographically. The RTVCL increased from 58% after the first treatment to 73% after the third treatment. RTVCL and Lipiodol retention were higher in responders than in non-responders. Tumours with expansive growth pattern showed a higher response rate (56%) than infiltrating tumours (20%). Mean survival of these patients was different (19 and 8 months; p < 0.01), respectively. Survival rates of all patients were 54, 22, and 11% after 1, 2 and 3 years, respectively. Repeated TACE shows local effectiveness. Three treatments during a period of one year are recommended for patients with Child-Pugh class A cirrhosis.

Adult↗
PubMed1994

Intravascular ultrasound: value of electronic and mechanical devices for quantifying mild to moderate atherosclerosis.

To define the accuracy of electronic and mechanical ultrasound (US) devices for determining the thickness of intima and media, 32 fresh normal and atherosclerotic human femoral arteries were obtained at necropsy. The samples were imaged with a 64-element array and a mechanically rotating US transducer at 20 MHz. The mean thickness of the intimal and medial layer was measured with electronic calipers followed by histopathologic and micromorphometric analysis. Morphometric correlation for intima showed r = 0.64 for the electronic and r = 0.58 for the mechanical US device. The correlation between ultrasonic and histologic measurement of medial thickness in normal and diseased specimens was r = 0.79 for the multielement and r = 0.76 for the mechanical transducer. In conclusion, multielement array transducers are equivalent to mechanically driven probes in the quantitative assessment of peripheral arterial wall layers. Both systems lack sufficient accuracy in the determination of mild to moderate intimal thickening.

Arteriosclerosis↗
PubMed1994

[Therapeutic interventional radiology procedures in hepatocellular carcinoma].

Interventional treatment of hepatocellular carcinoma is indicated if surgical treatment is impossible. Selection of the individual method of interventional treatment is determined by the size, location and number of tumors and by the grade of tumor vascularization. Tumors below 5 cm in diameter are well-suitable for aethanol ablation. In larger tumors and in tumors with high-grade vascularization transarterial chemoembolization is probably more effective. In patients with more than 3 tumor nodules chemoembolization is the treatment of choice. On the other hand chemoembolization shows reduced efficacy in tumors with low-grade hypervascularization and the aethanol ablation as a stand-alone procedure or supplemental treatment seems to be valuable. Until now there is no generally accepted opinion in terms of the indications for different methods of interventional treatment. Further comparative studies including aethanol ablation, chemoembolization and resection are necessary.

Carcinoma, Hepatocellular↗
PubMed1994

Transvenous and intra-arterial ultrasound monitoring of laser-assisted angioplasty.

To evaluate the effects of peripheral laser angioplasty in vivo, two new applications of intravascular ultrasound have been tested. Sonography of iliac and femoropopliteal arteries using 6.2-French/20-MHz transducers via a transvenous approach was technical feasible, however, spatial resolution of images was not equivalent to intra-arterial sonography. Catheters and guide wires could be observed in normal and moderate stenotic segments but not in occlusions. Using a combined 9-French multifiber-laser-ultrasound-catheter sonographic analysis of arterial stenoses revealed a reduction of the degree of stenoses from 84 +/- 8% before to 47 +/- 10% after laser angioplasty. Both imaging modalities detected bright echoes during pulsed laser energy delivery with a focal appearance within the occlusion material and a diffuse pattern involving the distal arterial lumen. Probably these effects are caused by optico-mechanical plaque disruptions and ejections of gaseous products during the laser ablation. Further development of combined catheter devices to guide energy delivery by continuous imaging might improve the results of laser angioplasty.

Aged↗
PubMed1993

Posttransplant renal artery stenosis--outpatient intraarterial DSA versus color aided duplex Doppler sonography.

A prospective trial was conducted to assess the accuracy of color aided duplex Doppler (CADD) sonography to rule out transplant renal artery stenosis (TRAS) and to determine feasibility and safety of intraarterial digital subtraction angiography (DSA) in hypertensive renal allograft recipients on an outpatient basis. All patients were hypertensive (n = 18, mean age: 42 +/- 11 years) and underwent CADD and an i.a. DSA with 4F catheters. There was a 4 hour rest post DSA. Duplex Doppler measurements of maximum velocity were obtained. Absolute values of > or = 100 cm/s were considered indicative to suspect TRAS. DSA revealed severe TRAS in 4 patients (22%). The stenoses were located near the iliorenal anastomosis (n = 2) and at the bifurcation of the renal artery (n = 2). Duplex Doppler classified twelve (67%) renal artery pedicles normal (maximum velocity: 79 +/- 23 cm/s). TRAS was suspected in 6 patients with a maximum velocity of 159 +/- 48 cm/s (P < 0.01). False positive CADD diagnoses were due to tortuous graft vessels and a postbiopsy arteriovenous fistula. Sensitivity of CADD was 100%, specificity 86%. There were no DSA related complications. No impairment of graft function occurred. CADD allows renal angiography to be reserved to clarify an inconclusive ultrasound study and for definite diagnosis of angiomorphology and lesion classification. Intraarterial DSA of renal grafts in outpatients may be performed without an increased risk of procedure-related complications.

Adult↗
PubMed1993

The double-line sign of osteonecrosis: evaluation on chemical shift MR images.

The MR appearance of osteonecrosis was assessed on selective fat and water images to further evaluate the features of the double-line sign of osteonecrosis. Conventional T1- and T2-weighted spin-echo and frequency selective chemical shift images of eight patients with avascular necrosis of the femoral head and three patients with bone infarcts were retrospectively reviewed. Eight of 11 patients showed a double-line sign on T2-weighted spin-echo images. In these cases correlation with selective water images revealed that a chemical shift artifact contributed to the appearance and location of the hyperintense line. The double-line sign was not seen in three patients with radiologically and clinically proven osteonecrosis. It is concluded that chemical shift imaging improves our understanding of the nature of the double-line sign.

Adult↗
PubMed1992

[Role of current diagnostic procedures in gastroenterology: MRI].

The diagnostic value of magnetic resonance imaging (MRI) in gastroenterology has not been definitely defined. In focal liver lesions MRI has a high sensitivity and aids in the differential diagnosis. In pathologies of the gall bladder and the pancreas, MRI currently has no clinical relevance. MRI diagnosis of pelvic fistulas and abscesses in chronic inflammatory bowel disease is both sensitive and specific. MRI is superior to CT in detecting and differentiating recurrent rectal cancer.

Diagnosis, Differential↗
PubMed1992

In vitro and clinical feasibility study with an over-the-wire delivery system for pulsed dye laser angioplasty.

The suitability of a pulsed dye laser (504 nm) in experimental and clinical angioplasty was investigated. In an experimental study, the ablation thresholds were 3 J/cm2 +/- 8 (mean +/- standard deviation) for fibrofatty plaque and 25 J/cm2 for calcified tissues under saline. At a radiant exposure of 10 J/cm2 the etch rates were 1.7 microns per pulse +/- 0.3 for media, 2.8 microns/pulse +/- 0.4 for normal intima, and 3.9 microns/pulse +/- 1.1 for fibrofatty plaque (P less than .05). Pressure wave effects with a separation of tissue layers were predominantly localized at the internal elastic lamina. Thermal injury with vacuolations extended 15 microns +/- 6 into adjacent tissue. For clinical study, laser-assisted balloon angioplasty was performed in 10 patients (64 years +/- 14) with occlusions of peripheral arteries using a 9-F multifiber ring catheter. Lesion length ranged from 2 to 12 cm (mean, 7 cm). Laser angioplasty with an 80 mJ/pulse decreased the mean stenosis from 100% to 58% +/- 12% (P less than .005). The ankle-brachial index rose from a median of 0.48 to 0.88 (P less than .001). In 33% of patients, there were subintimal dissections after laser angioplasty. After a mean follow-up of 10.2 months, the overall clinical success was 70% with a primary patency of 78%. The over-the-wire approach with a pulsed dye laser may constitute a safe and feasible tool in laser angioplasty.

Angioplasty, Laser↗
PubMed1992

Noninvasive procedures for diagnosis of renovascular hypertension in renal transplant recipients--a prospective analysis.

The purpose of this study was to clarify the selectivity and specificity of noninvasive procedures for diagnosis of clinically suspected posttransplant renovascular hypertension. We prospectively investigated 25 renal transplant recipients with arterial hypertension and clinically suspected stenosis of the graft artery (8 female and 17 male patients; ages 45 +/- 15 years). We performed a captopril test with 25 mg captopril (n = 25), renography with technetium-99m diethylene triamine penta-acetic acid (99mTc-DTPA) before and after angiotensin-converting enzyme (ACE) inhibition with determination of glomerular filtration rate (GFR) and effective renal plasma flow (ERPF) (n = 23) and color-coded duplex ultrasonography of the transplant kidney vessels (n = 24). Renal transplant artery stenosis (RTAS) was excluded by renal arteriography in 20 patients and by operative evaluation or clinical follow-up in 5 patients. We identified 4 patients with RTAS and renovascular hypertension. The noninvasive methods showed the following results (sensitivity/specificity): (1) captopril test: 75%/67%; (2) renography combined with ACE-inhibition: 75%/84%; and (3) color-coded duplex ultrasonography: 100%/75%. We conclude that in patients with clinical evidence of RTAS most noninvasive diagnostic procedures are not sufficiently accurate to exclude the diagnosis. Only color-coded duplex ultrasonography did not fail to detect all patients with RTAS and may act as a screening test. Intraarterial renal angiography remains the most reliable and as-yet indispensable diagnostic test for transplant recipients to rule out RTAS.

Adult↗
PubMed1992

Comparison of pulsed laser-assisted angioplasty and balloon angioplasty in femoropopliteal artery occlusions.

The authors performed a prospective, comparative study of 96 patients (age, 41-87 years) with femoropopliteal artery occlusions. Laser-assisted angioplasty was performed in 64 patients with 9- and 7-F over-the-wire multifiber catheters. Supplemental balloon dilation was performed after laser angioplasty. Thirty-two patients underwent excimer laser angioplasty (ELA), and 32 underwent pulsed dye laser angioplasty (DLA). The remaining 32 patients underwent conventional balloon angioplasty (BA). The length of occlusions was 3-10 cm (mean, 6.3 cm). Lesion characteristics in the three patient groups were similar. Technical success rates were 84% for ELA, 78% for pulsed DLA, and 81% for conventional BA. The 1-year clinical success rate was 69% (22 of 32 patients) in the ELA group, 63% (20 of 32 patients) in the pulsed DLA group, and 66% (21 of 32 patients) in the BA group (differences were not significant). Laser-assisted angioplasty with multifiber catheters in femoropopliteal artery occlusions did not help improve the technical success rate and 1-year clinical success rate when compared with those of conventional BA.

Adult↗
PubMed1992

[Percutaneous transhepatic cholangioscopic color laser lithotripsy in bile duct calculi].

Tunable dye laser lithotripsy is an effective and low risk treatment in patients with bile duct stones in which transpapillary maneuvers failed. The percutaneous approach allows to introduce small caliber endoscopes (10.5 F) to fragment the calculi under vision. This technique was evaluated in 8 patients who had undergone a biliodigestive anastomosis or in whom the biliary calculi could not removed by standard retrograde treatment. Laser lithotripsy resulted in sufficient fragmentation in 7 patients. Bile duct clearance proved to be a particular problem with the percutaneous access. When a retrograde sphincterotomy is not possible an antegrade papillotomy must be attempted under fluoroscopic guidance. In bile duct strictures the implantation of expandable stents facilitates the passage of fragments and may prevent recurrent stricture and development of new stones.

Aged↗