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Biomedical subjects

D Szolar

Publications and source records attributed to D Szolar.

At least 19 recordsLinked to original sources
PubMed2001

Multislice CT-image-guided endoscopic sinus surgery using an electromagnetic tracking system.

Our objective was to assess the practicability and accuracy of a computer-assisted multislice CT-guided frameless electromagnetic tracking for endoscopic sinus surgery. Eighty-two patients with various paranasal sinus diseases were evaluated. Prior to surgery, axial multislice spiral-CT scans with 2.5-mm collimation, 0.8-mm reconstruction increment, and a pitch of 3 were acquired. After Ethernet transfer of the CT data set to the guidance system, coronal and sagittal images were reconstructed. For intraoperative navigation the Insta Trak System (Visualization Technology, Boston, Mass.) was used. Navigational procedures are described in detail in the paper. Accuracy was assessed by means of visual landmarks which could be clearly identified endoscopically as well as on CT images. A second parameter for accuracy was calculated by the system itself as the root mean square (RMS). The system was able to display the position of the aspirating tip relative to anatomical structures with an average accuracy of 0.70 +/- 0.40 mm. Root mean square values showed a mean value of 0.40 +/- 0.20 mm. During surgical procedures the Insta Trak System provides the surgeon with additional image-based information to the endoscopic view. The device accuracy is high and the system proves to be practicable and efficient in ENT surgery.

Adolescent↗
PubMed2001

Peripheral primitive neuroectodermal tumour of the kidney: CT findings.

Peripheral primitive neuroectodermal tumour in the kidney is a rare entity with high malignant potential. The distinctive demographic, clinical and radiological findings, as described in the present case, should suggest this aggressive tumour in the differential diagnosis of renal neoplasms in adolescents.

Adolescent↗
PubMed2001

Cystic adventitial degeneration of the popliteal artery-the diagnostic value of duplex sonography.

Cystical adventitial degeneration of the popliteal artery is a disorder which is difficult to diagnose, due to the similarity of the symptoms of people presenting with peripheral arterial occlusive disease (PAOD) or popliteal entrapment syndrome. The only thing that differs from patients suffering from PAOD is the lack of typical risk factors for arteriosclerosis. Typical diagnostic procedures like conventional angiography or magnetic resonance Imaging angiography can be negative, too and therefore misleading. The only which is crucial in the diagnosis of cystic adventitial degeneration of the popliteal artery is to know the morphological background of this disorder, namely that it is a cyst of the adventitia of the artery which leads to a dynamic exercise-dependent flow inhibition. We present a 57-year old white male who had a week's history of intermittent claudication in his left calf. He was lacking of typical risk factors for arteriosclerosis and on first examination all pulses in both lower extremities were palpable and Doppler index on both legs was >1. Only duplexsonography revealed a cystic formation impressing the left popliteal artery in the hight of the rift in the popliteal joint.

Arterial Occlusive Diseases↗
PubMed2000

Small-bowel disease: comparison of MR enteroclysis images with conventional enteroclysis and surgical findings.

PURPOSE: To investigate if magnetic resonance (MR) enteroclysis can be performed routinely and to compare MR enteroclysis findings with those of conventional enteroclysis or surgery. MATERIALS AND METHODS: MR enteroclysis was prospectively performed in 30 patients with symptoms of inflammatory bowel disease or small-bowel obstruction (SBO). A methylcellulose-water solution was used to distend the small bowel. To monitor dynamic changes in the small bowel, a single-shot fast spin-echo T2-weighted sequence was applied. For morphologic assessment, breath-hold T2-weighted fast spin-echo and coronal T1-weighted gradient-recalled-echo MR images were obtained without and with gadolinium enhancement. Image quality and degree of small-bowel distention were graded. MR imaging findings and degree of SBO were compared with findings at conventional enteroclysis (n = 25) or surgery (n = 5). RESULTS: MR enteroclysis was well tolerated and provided adequate image quality and sufficient small-bowel distention. SBO grade based on MR enteroclysis images (n = 10) was identical to that based on conventional enteroclysis images (n = 6) or surgical findings (n = 4). There was exact agreement between MR enteroclysis and retrospective findings in all five patients who underwent surgery, and MR findings were identical to those at enteroclysis in 18 patients, superior in six patients, and inferior in one patient. CONCLUSION: MR enteroclysis can be performed routinely with adequate image quality and sufficient small-bowel distention. The functional information provided by MR enteroclysis is identical to that provided at conventional enteroclysis.

Adult↗
PubMed2000

Osteomyelitis of the spine and abscess formation in the left thigh after stent-graft implantation in the superficial femoral artery.

PURPOSE: To present a rare case of abscess formation around a covered stent in the superficial femoral artery. METHODS AND RESULTS: Two weeks after balloon dilation of a left superficial femoral artery (SFA) occlusion, during which a Hemobahn covered stent had been placed to treat dissection, a 77-year-old nondiabetic male developed intolerable pain and swelling of his left thigh. An abscess had formed around the stent, which was patent; intravenous antibiotic therapy quelled the symptoms, and the patient discontinued his oral antibiotic regimen weeks after discharge. General septicemia ensued. Acute lower limb ischemia and excruciating back pain prompted readmission. The SFA stent-graft occlusion required femoropopliteal bypass; the abscess and spondylodiskitis that had developed in the T12 and L1 vertebrae responded to intravenous antibiotics. The patient is without signs of infection at 6 months. CONCLUSIONS: Local and systemic infections associated with intraluminal prostheses are rare, and prophylactic antibiotic therapy is not commonly employed. Balloon- or device-induced arterial injury may expose the arterial wall to bacterial colonization, suggesting that patients receiving lengthy stents or experiencing arterial injury during angioplasty should receive antibiotics as a precautionary measure.

Abscess↗
PubMed1999

Contrast-enhanced MR imaging of two superparamagnetic RES-contrast agents: functional assessment of experimental radiation-induced liver injury.

The purpose of this study was to compare liver contrast-enhancing characteristics of two superparamagnetic reticuloendothelial system (RES)-directed agents with different particle sizes, polycrystalline iron oxide nanocompounds (PION) and carboxydextran-coated maghemite (DDM128N/389, later referred to as DDM128), in an experimental model of focal radiation-induced hepatitis. PION, for the small particle size (31 nm), and DDM128, for the large particle size (59 nm), RES-directed agents were compared for liver enhancement after radiation-induced liver injury. A single x-irradiation exposure varying from 10 to 60 Gy was delivered to one side of the liver. T2-weighted spinecho magnetic resonance imaging was performed 3 days after x-irradiation at 30 minutes post-contrast. Using the RES-directed PION, the normal, non-irradiated portion of the liver decreased in signal intensity with a maximum negative enhancement of -66%, while the irradiated portion of the liver decreased in signal intensity by -24% (60 Gy). The signal intensity decline of irradiated liver tissue using PION was dose dependent, but was found at all radiation dose levels (10-60 Gy). The difference in signal intensity between irradiated (-63%) and non-irradiated (-82%) portions was also statistically different using DDM128 at 60 Gy. However, lower irradiation doses (10 and 30 Gy) failed to produce a statistically significantly different enhancement in the irradiated and non-irradiated portion of the liver. Sensitivity of liver enhancement with RES-directed agents is size dependent. The smaller particle (PION) is more sensitive for detection of radiation-induced hepatitis than the larger particle (DDM128). The relative insensitivity of DDM128 enhancement for diffuse liver injury will be clinically advantageous for detecting focal lesions in the presence of diffuse hepatic injury.

Animals↗
PubMed1999

Renal masses--evaluation by amplitude coded colour Doppler sonography and multiphasic contrast-enhanced CT.

OBJECTIVE: To assess the efficacy of amplitude coded colour Doppler US (aCDS) in the evaluation of renal masses as shown by multiphasic contrast-enhanced CT. MATERIAL AND METHODS: Eighty patients (155 kidneys) with suspicion of renal masses underwent aCDS and spiral CT. The findings were classified into normal kidneys, kidneys with tumours, kidneys with cysts, and those with "other findings" (i.e. bleeding, calcifications, inflammation, parenchymal hypertrophy). The aCDS findings were compared to CT results and to histological findings or clinical, laboratory and follow-up data. RESULTS: Eighteen renal cell carcinomas and 8 other tumours were found; 78 kidneys had cysts, 12 polycystic kidneys and 10 fibrotic kidneys were detected, 20 kidneys showed other findings. Diagnostic aCDS data were obtained in 129 kidneys (83.2%) showing pathology with an accuracy of 94%. CT adequately showed pathology in all patients with some diagnostic uncertainty in the evaluation of complicated cysts. CONCLUSION: Though contrast-enhanced multiphasic spiral CT is the method of choice for evaluating renal masses, US including aCDS can provide valuable information, particularly in differentiating vascularized from non-vascularized lesions and in the evaluation of complicated renal cysts.

Adult↗
PubMed1997

[Evaluation of renal vascularization using amplitude-coded Doppler ultrasound].

PURPOSE: To evaluate the benefit of "Colour Doppler Energy" (CDE) or "Power Doppler" applications in healthy kidneys and in renal disease including paediatric assessment. PATIENTS AND METHOD: Ten healthy volunteers (range: neonate to adults) were studied using conventional colour Doppler sonography (CDS) and CDE in order to evaluate the visibility of intrarenal vasculature. In addition, ten children and ten adults with known renal disease were evaluated. The findings were compared to clinical, scintigraphic and biopsy results. RESULTS: CDE showed far better visualisation of intrarenal vasculature than CDS. CDE demonstrated focal and diffuse reduced cortical perfusion with an overall accuracy of 95% and a sensitivity of 88%. In 7 healthy volunteers cortical vasculature was visualised throughout the kidney. In 3 infants incomplete visualisation was obtained because of motion artifacts. In the diseased kidneys, CDE findings correlated well with clinical findings, scintigraphy results and biopsy findings. CONCLUSION: CDE can be successfully applied to adults and infants demonstrating renal vasculature in healthy kidneys and in kidneys with focally or diffusely altered perfusion.

Adolescent↗
PubMed1997

Postoperative radiotherapy in radically resected non-small cell lung cancer.

PURPOSE: To evaluate the value of adjuvant postoperative external-beam radiation (EBR) in patients with radically resected non-small cell lung cancer (NSCLC) pT1-3 pN0-2 compared to patients with resected NSCLC without adjuvant EBR. MATERIALS AND METHODS: In 155 patients (121 male, 34 female; mean age, 59 years) 105 lobectomies, 12 bilobectomies, and 38 pneumonectomies with radical lymph node dissection of the contralateral [corrected] side were performed. Postoperative staging was done according to the TNM system and was as follows: pT1 (n=38), pT2 (n=89), pT3 (n=28); pN0 (n=39), pN1 (n=67) and pN2 (n=49). Histopathologic study revealed 68 squamous cell carcinomas, 53 adenocarcinomas, 21 large cell carcinomas, 6 adenosquamous cell carcinomas, and 7 bronchioloalveolar cell carcinomas. All patients were randomly assigned into two treatment groups: 72 patients with no further treatment (control group), and 83 patients (EBR group) with adjuvant postoperative EBR of the bronchial stump and mediastinum (50 to 56 Gy, 8 or 23 MV photons, 2 Gy/d, 5 d/wk) beginning 4 to 6 weeks after surgery. RESULTS: The overall 5-year survival rate (median observation time, 43 months) of all patients was 24.1% (EBR group, 29.7%; control group, 20.4%; p>0.05, not significant). The relative risk of the EBR group was 0.85 with a two-sided confidence interval of 0.66 to 1.09. The overall 5-year recurrence-free survival was 20.6% (EBR, 27.1%; control group, 15.6%; p=0.07). The relative risk of the EBR group was 0.80 with a confidence interval of 0.63 to 1.01. The rate of local recurrences at the bronchial stump and/or mediastinum was significantly smaller in the EBR group (n=5) than in the control group (n=17) (p<0.01). Multivariate analysis (chi2 test) demonstrated an independent influence of postoperative EBR on the incidence of local recurrences. The incidence of distant metastases was slightly but not significantly higher in patients without EBR (38 patients) compared to those who had EBR (32 patients). CONCLUSION: High-dose postoperative EBR to the mediastinum significantly reduces the risk of local recurrence at the bronchial stump and/or mediastinum. Age, sex, histologic subtype, tumor size, surgical approach, or extent of lymph node involvement had no prognostic value--only postoperative EBR had an independent influence on the risk of local recurrence. The effect of postoperative EBR was on the verge of significance with respect to recurrence-free survival and showed the same tendency in overall survival, however with an attenuated relative risk.

Adenocarcinoma↗
PubMed1996

Quantification of the extent of area at risk with fast contrast-enhanced magnetic resonance imaging in experimental coronary artery stenosis.

Fast magnetic resonance (MR) imaging techniques have the capability of demonstrating regions of ischemia caused by stenosis. The size of the potentially ischemic area determines the importance of the stenosis. The purpose of this study was to determine the relative values of relaxivity-enhancing and magnetic-susceptibility MR contrast media in detecting and sizing the area at risk in dogs. Eight dogs were subjected to critical left circumflex coronary artery (LCX) stenosis. Sixty sequential inversion-recovery- and driven-equilibrium-prepared fast gradient recalled echo images were acquired during bolus administration of 0.03 mmol/kg gadodiamide or 0.4 mmol/kg sprodiamide in basal and vasodilated (dipyridamole-stress) states. The size of the area at risk was measured and compared with that measured post mortem. In the basal state, gadodiamide and sprodiamide equivalently altered the signal intensities of nonischemic myocardium and the territory of stenosed coronary artery. Dipyridamole produced a significant increase in left anterior descending coronary artery flow with a decrease in LCX flow. The hypoperfused region was observed as a low-and high-signal intensity region after administration of gadodiamide and sprodiamide, respectively. The size of the hypoperfused region was slightly smaller with gadodiamide (37.4% +/- 2.8%) and sprodiamide (34.0% +/- 2.2%) than the true area at risk measured post mortem (41.8% +/- 2.2%; p < 0.05). Dipyridamole perfusion MR imaging with relaxivity or susceptibility contrast media is a noninvasive method to identify and quantify the area at risk in the territory of a stenotic coronary artery. Changes in myocardial signal intensity on fast gradient recalled echo images reflect the augmentation of flow and volume induced with dipyridamole and are consistent with the "steal phenomenon."

Animals↗
PubMed1996

Assessment of hemodynamic effects of angiotensin-converting enzyme inhibitor therapy in chronic aortic regurgitation by using velocity-encoded cine magnetic resonance imaging.

Long-term treatment with angiotensin-converting enzyme (ACE) inhibitors has beneficial effects in patients with chronic aortic regurgitation by reducing left ventricular volumes and regurgitant fraction. Velocity-encoded cine magnetic resonance imaging can directly measure antegrade (forward stroke volume) and retrograde blood flow (regurgitant volume) in the ascending aorta. Velocity-encoded cine magnetic resonance imaging was used in 9 patients with moderate to severe aortic regurgitation (regurgitant fraction 49% +/- 17%) to measure regurgitant fraction, regurgitant volume, and forward stroke volume at baseline and 3 months after therapy with enalapril (mean dose 29 +/- 13 mg). Ten additional patients with aortic regurgitation without any drug therapy served as a control group. In the treatment group, systolic blood pressure slightly decreased from 132 +/- 20 mm Hg to 121 +/- 14 mm Hg (p = not significant), whereas diastolic blood pressure and heart rate (beats per minute) remained unchanged. Regurgitant fraction decreased in 6 patients (responders) from 49% +/- 19% to 39% +/- 20% (percentage change 24% +/- 14%, p = 0.002) and was unchanged in 3 patients (nonresponder, 49% +/- 19% vs 51% +/- 16%; p = not significant). In the responder group, forward stroke volume increased from 128 +/- 32 ml to 148 +/- 57 ml, whereas regurgitant volume remained unchanged (67 +/- 40 ml vs 65 +/- 51 ml). At baseline, the responder group had a significant higher total vascular resistance than the nonresponder group (998 +/- 538 dyne.sec.cm-5 vs 625 +/- 214 dyne.sec.cm-5; p < 0.05). With enalapril treatment, total vascular resistance in the responder group tended to decrease (891 +/- 576 dyne.sec.cm-5), but slightly increased in the nonresponder group (679 +/- 276 dyne.sec.cm-5). The control group showed no changes in regurgitant fraction, regurgitant volume, forward stroke volume, and total vascular resistance at follow-up.

Adult↗
PubMed1996

Acute hemodynamic effects of recently developed monomer and dimer magnetic resonance imaging contrast media: a comparative study.

RATIONALE AND OBJECTIVES: We evaluated and compared the acute cardiovascular effects of equiosmolar doses of recently developed nonionic monomer and macrocyclic dimer magnetic resonance (MR) imaging contrast media with the clinically available ionic and nonionic MR contrast media. METHODS: Normotensive adult Sprague-Dawley rats were divided into six groups of seven rats per group. Group 1 received the nonionic monomer Gd-CMPA-BMPA (500 mmol/l solution); group 2 received the nonionic dimer Gd(2)2(O)DO3A (500 mmol/l solution); group 3 also received Gd(2)2(O)DO3A but at a higher concentration (1,000 mmol/l solution); group 4 received gadopentetate dimeglumine (500 mmol/l solution); and group 5 received gadodiamide (500 mmol/l solution). Each rat received a rapid (1-2 sec) bolus intravenous injection of 0.1, 0.25, and 0.5 mmol/kg of each contrast agent. Group 6 was used to test the peak effects of quiosmolar glucose solutions (500, 1,000, and 2,000 mOsm/kg water). Data were acquired at baseline, 20 sec (peak effect) after injection, and 1, 3, 5, and 10 min after injection. Peripheral (systolic, diastolic, and mean) pressure, central venous pressure, left ventricular (LV) pressure (peak systolic and end diastolic) pressure, first derivative of left ventricular pressure (+/-dP/dt), rate pressure product, and heart rate were measured. RESULTS: Bolus administration (0.1, 0.25, and 0.5 mmol/kg) of Gd-CMPA-BMPA and gadodiamide (500 mmol/l) had no significant effects on the monitored cardiovascular parameters. Bolus injection of 0.25 and 0.5 mmol/kg Gd(2)2(O)DO3A (500 and 1,000 mmol/l) and gadopentetate dimeglumine (500 mmol/l) caused transient cardiovascular depression, including decreased peripheral blood pressure, LV systolic pressure, peak positive and negative dP/dt, and rate pressure product, but an increased LV end diastolic pressure. These cardiovascular effects were slightly less profound than those produced by gadopentetate dimeglumine. CONCLUSION: Gd-CMPA-BMPA and gadodiamide have no adverse cardiovascular effects. Gd(2)2(O)DO3A and gadopentetate dimeglumine cause vasodilation and reduced cardiac performance. Therefore, presuming similar effects, if Gd(2)2(O)DO3A and gadopentetate dimeglumine are to be used at high doses for the MR quantification of blood volume or as a bolus for perfusion study, appropriate consideration should be given to possible adverse physiologic changes.

Animals↗