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Biomedical subjects

T J Vogl

Publications and source records attributed to T J Vogl.

At least 19 recordsLinked to original sources
PubMed2004

Traumatic injuries of the pelvis and thoracic and lumbar spine: does thin-slice multidetector-row CT increase diagnostic accuracy?

The objective is to evaluate different multidetector-row CT (MDCT) strategies for adequate classification of spinal and pelvic injuries. Seventy intubated patients after multiple trauma underwent conventional radiography (CR) and MDCT. Examinations included the pelvis (P), the lumbar spine (LS) and the thoracic spine (TS). Conventional radiographs, 3-mm (CT5) and 5-mm scans (CT3) and 3-mm and 5-mm scans combined with MPR (CT3R/CT5R) were compared to surgery, autopsy and clinical course. MDCT led to significantly better results than CR (P<0.01). Correlation coefficients were r=1.0 (CT3R), r=0.96 [TS] to r=1.0 [P/LS] (CT5R), r=0.8 [P] to r=1.0 [TS] (CT3), r=0.80 [P] to r=0.86 [TS] (CT5) and r=0.3 [TS] to r=0.69 [P] (CR). Fractures were identified by CT3R in 100% of cases, by CT5R in 95%, by CT3 in 90% [P]-100% [TS], by CT5 in 83.3% [LS]-90% [P] and by CR in 57.1% [TS]-87.2% [P]. Unstable fractures were identified in 100% by CT3R, CT5R and CT3, 85.7% [TS]-100% [P/LS] by CT5 and 57.1% [TS]-80% [P] by CR. Only overlapping thin-slice multiplanar reformation allows for an adequate classification of spinal and pelvic injuries and thus is highly emphasized in patients after severe blunt trauma.

Adult↗
PubMed2004

[Modern diagnosis of lung nodules].

Despite numerous technical improvements, modern diagnosis of lung nodules can still be divided into three partially overlapping stages: (1) detection, (2) characterization, and (3) follow-up and management. With respect to these steps, this article reviews the diagnostic significance of different modalities. New and not definitively evaluated techniques are considered. Furthermore, methods that are not routinely applied but have been published and are thought to have some value in the characterization of pulmonary lung nodules are discussed. Statistical data are included to assist the classification of the results of imaging. Remarks on biopsy of lung nodules to obtain histopathologic correlation complete this overview. The authors are convinced that the established methods (radiography for detection, spiral CT for characterization), after thorough evaluation, will soon be replaced by magnetic resonance imaging (MRI). Recent experience with MRI points to its potential for detection and characterization of pulmonary nodules while avoiding ionizing radiation. The development of indications for MRI of the lung (e.g. paediatric radiology) will be fascinating to observe.

Humans↗
PubMed2004

[Laser-induced thermotherapy of lung metastases and primary lung tumors].

We present laser-induced thermotherapy (LITT) of primary and secondary lung tumors analysing indications and technical concepts. Thirty patients with lung metastases of different primary tumors (n=24) as well as localized lung tumors (n=6) were prospectively treated in 41 sessions using laser-induced thermotherapy (LITT). An MR-compatible puncture system was used with direct puncture technique. The puncture was performed via CT guidance in care vision technique. Eight patients were thermoablated using MR tomographical monitoring, 22 patients using CT monitoring. Local therapy effects, tumor control rate, side effects, complications, and survival were evaluated. In 74% of cases (28/38 lesions) of 24 patients with lung metastases and in all cases of the 6 patients with lung carcinoma a complete local ablation could be achieved. The complication rate (pneumothorax) was 9,8%. One patient with bronchial carcinoma had to be thoracotomized and resected. 93% of the patients are still alive. Percutaneous LITT of lung tumors permits a complete ablation of lung metastases and lung carcinomas with a low complication rate. Indications for the procedure were defined for patients with no more than 5 metastases up to 3 cm in size.

Adult↗
PubMed2004

[Remote access to a web-based image distribution system].

PURPOSE: To assess different network and security technologies for remote access to a web-based image distribution system of a hospital intranet. MATERIALS AND METHODS: Following preparatory testing, the time-to-display (TTD) was measured for three image types (CR, CT, MR). The evaluation included two remote access technologies consisting of direct ISDN-Dial-Up or VPN connection (Virtual Private Network), with three different connection speeds of 64, 128 (ISDN) and 768 Kbit/s (ADSL-Asymmetric Digital Subscriber Line), as well as with lossless and lossy compression. RESULTS: Depending on the image type, the TTD with lossless compression for 64 Kbit/s varied from 1 : 00 to 2 : 40 minutes, for 128 Kbit/s from 0 : 35 to 1 : 15 minutes and for ADSL from 0 : 15 to 0 : 45 minutes. The ISDN-Dial-Up connection was superior to VPN technology at 64 Kbit/s but did not allow higher connection speeds. Lossy compression reduced the TTD by half for all measurements. CONCLUSIONS: VPN technology is preferable to direct Dial-Up connections since it offers higher connection speeds and advantages in usage and security. For occasional usage, 128 Kbit/s (ISDN) can be considered sufficient, especially in conjunction with lossy compression. ADSL should be chosen when a more frequent usage is anticipated, whereby lossy compression may be omitted. Due to higher bandwidths and improved usability, the web-based approach appears superior to conventional teleradiology systems.

Internet↗
PubMed2004

[Grading of carotid artery stenosis using high resolution dynamic magnetic resonance angiography in comparison to intraarterial digital subtraction angiography. Are stenoses over 70% reliably detectable?].

PURPOSES: Evaluation of high resolution dynamic magnetic resonance angiography (ceMRA) in detection and graduation of carotid artery stenosis in comparison to intraarterial digital subtraction angiography. MATERIALS AND METHODS: Magnetic resonance angiography and intraarterial digital subtraction angiography was performed in 65 patients with suspected carotid artery stenosis by ultrasound examination. Detection and graduation of carotid artery stenosis by magnetic resonance angiography were compared to those of intraarterial digital subtraction angiography after stenosis grading according to NASCET criteria. RESULTS: All magnetic resonance angiographies were of excellent quality, with 46 stenoses type I and II and 12 stenoses type III NASCET correctly identified and classified by magnetic resonance angiography. Overestimation was found in 4 cases and underestimation in 2 cases. Both modalities detected 13 occlusions. Sensitivity and specificity of ceMRA were 92%. The positive predictive value was 86% and the negative predictive value 96%. CONCLUSION: High resolution dynamic magnetic resonance angiography is suitable in detecting and classifying carotid artery stenoses over 70% with high sensitivity and specificity in comparison to intraarterial digital subtraction angiography. Intraarterial digital subtraction angiography should only be performed in critical cases.

Aged↗
PubMed2004

[Reference values of MRI flow measurements of the pulmonary outflow tract in healthy children].

PURPOSE: To provide reference values for MRI-based flow measurements in the main pulmonary artery in healthy children. MATERIALS AND METHODS: In 98 healthy children (age: 3 - 17 years, median: 11 years), the main pulmonary artery was examined using MRI-based flow measurements with high temporal resolution (9.6 ms per cardiac phase). RESULTS: The acceleration time revealed a distinct age dependency and varied between 90 and 155 ms (mean: 124 ms +/- 14). The relative acceleration time (related to the RR-interval) varied between 12.7 and 27 % (mean: 18 % +/- 2.6). The mean values and the standard deviations for the determined values were as follows: cardiac output (5.4 l/min +/- 1.4), cardiac output normalized to the body surface area (4.2 [l/min]/m(2) +/- 0.8), average systolic flow velocity (66 cm/s +/- 12), maximum systolic flow (309 ml/s +/- 79), mean flow (110 ml/s +/- 30), distensibility of the wall of the main pulmonary artery (79 % +/- 26), peak velocity (96 cm/s +/- 15), pressure gradient along the pulmonary valve (3.8 mm Hg +/- 1.2), stroke volume (63.2 ml +/- 17.9), acceleration volume (23.7 ml +/- 8.7), maximum acceleration of flow (4924 ml/s(2) +/- 1431), and reverse volume (0.2 ml +/- 0.3). CONCLUSIONS: The acquired values of reference are applicable to all pediatric patients and serve as a framework for the communication between the radiologist and the pediatric cardiologists. High temporal resolution of the measurement sequence is mandatory. Noticeable deviations of these values should induce additional (probably invasive) evaluation.

Adolescent↗
PubMed2003

Infarct remodeling after intracoronary progenitor cell treatment in patients with acute myocardial infarction (TOPCARE-AMI): mechanistic insights from serial contrast-enhanced magnetic resonance imaging.

BACKGROUND: Experimental and initial clinical studies suggest that transplantation of circulating blood- (CPC) or bone marrow-derived (BMC) progenitor cells may beneficially affect postinfarction remodeling processes after acute myocardial infarction (AMI). To relate functional characteristics of the infused cells to quantitative measures of outcome at 4-month follow-up, we performed serial contrast-enhanced MRI and assessed the migratory capacity of the transplanted progenitor cells immediately before intracoronary infusion. METHODS AND RESULTS: In 28 patients with reperfused AMI receiving either BMCs or CPCs into the infarct artery 4.7+/-1.7 days after AMI, serial contrast-enhanced MRI performed initially and after 4 months revealed a significant increase in global ejection fraction (from 44+/-10% to 49+/-10%; P=0.003), a decrease in end-systolic volume (from 69+/-26 to 60+/-28 mL; P=0.003), and unchanged end-diastolic volumes (122+/-34 versus 117+/-37 mL; P=NS). Infarct size, measured as late enhancement (LE) volume, decreased significantly, from 46+/-32 to 37+/-28 mL (P<0.05). There was a significant correlation between the reduction in LE volume and global ejection fraction improvement. The migratory capacity of transplanted cells as assessed ex vivo toward a gradient of vascular endothelial growth factor for CPCs and stromal cell derived factor-1 for BMCs was closely correlated with the reduction of LE volume. By multivariate analysis, migratory capacity remained the most important independent predictor of infarct remodeling. CONCLUSIONS: Analysis of serial contrast-enhanced MRI suggests that intracoronary infusion of adult progenitor cells in patients with AMI beneficially affects postinfarction remodeling processes. The migratory capacity of the infused cells is a major determinant of infarct remodeling, disclosing a causal effect of progenitor cell therapy on regeneration enhancement.

Cell Movement↗
PubMed2003

Upload capacity and time-to-display of an image Web system during simultaneous up- and download processes.

The aim of this study was to assess the up- and download performance of an image Web system (IWS) during simultaneous up- and download procedures. Following preparatory tests, the upload capacity (UC) with and without simultaneous download and the time-to-display (TTD) with and without simultaneous upload were determined for different image, server and compression types, and with up to 16 concurrent clients. The UC varied between 1.7-5.5 Gigabyte per hour (GB/h) and was slightly influenced by a simultaneous download; however, the TTDs were substantially prolonged during an upload and only below 5 s with up to four to six concurrent clients. The choice of image and server type had a strong impact on UC and TTD. Lossy primary compression proved slightly superior. An effective UC of approximately 4.0 GB/h or 96 Gigabyte per day (GB/day) can be achieved, which appears suitable even for large institutions. Because of its substantial influence on UC and TTD during simultaneous up- and download, the server hardware should be equipped with two processors and 1 GB RAM. Lossy primary compression may be used with slight performance benefits when full-resolution images are not required. The upload is a time-demanding process, and it is possible that during peak hours the waiting times are unacceptable for clinicians.

Data Compression↗
PubMed2003

Performance of Web-based image distribution: server-oriented measurements.

The aim of this study was to assess the performance of Web-based image distribution when multiple personal computers (PCs) are downloading images simultaneously for different server hardware configurations. Using specially developed software, the time-to-display (TTD) of different image types was measured with up to 16 concurrent PCs for various combinations of processor, random access memory (RAM), network connection and image compression. The TTD increased linearly with the number of concurrent PCs but remained under 5 s in most of the cases, even with 16 concurrent PCs. Only with a 10-Mbit/s network connection or with lossy compression were TTDs above 5 s obtained. Two processors instead of one led to a slight and constant improvement of the TTD. Reducing the amount of RAM increased the TTD mainly for computed radiography (CR) images. There was no difference between a 200- and 100-Mbit/s network, but 10 Mbit/s proved significantly worse. When increasing the number of clients lossless compression performed substantially better than lossy. A standard off-the-shelf server provides an appropriate download performance even with 16 concurrent clients. Processor speed and RAM amount are of minor importance, but it is highly recommended to use a 100-Mbit/s network connection and to avoid the application of on-demand lossy compression in a local area network.

Internet↗
PubMed2003

Performance of Web-based image distribution: client-oriented measurements.

The aim of this study was to define a clinically suitable personal computer (PC) configuration for Web-based image distribution and to assess the influence of different hard- and software configurations on the performance. Through specially developed software the time-to-display (TTD) for various PC configurations was measured. Different processor speeds, random access memory (RAM), screen resolutions, graphic adapters, network speeds, operating systems and examination types (computed radiography, CT, MRI) were evaluated, providing more than half a million measurements. Processor speed was the most relevant factor for the TTD; doubling the speed halved the TTD. Under processor speeds of 350 MHz, TTD mostly remained above 5 s for 1 CR or 16 CT images. Here Windows NT with lossy compression were superior. Processor speeds of 350 MHz and over delivered TTD <5 s. In this case Windows 2000 and lossless compression were preferable. Screen resolutions above 1280 x 1024 pixels increased the TTD mainly for CR images. The RAM amount, network speed and graphic adapter did not have a significant influence. The minimum threshold for clinical routine is any standard off-the-shelf PC better than Pentium II 350 MHz, 128 MB RAM; hence, high-end PC hardware is not required.

Computers↗
PubMed2003

Phase II study of the efficacy and safety of cisplatin-epinephrine injectable gel administered to patients with unresectable hepatocellular carcinoma.

PURPOSE: To study the efficacy and safety of percutaneous cisplatin-epinephrine (CDDP-EPI) injectable gel in patients with localized unresectable hepatocellular carcinoma (HCC). PATIENTS AND METHODS: Eligible patients had histologically proven HCC, no prior treatment except for surgery, and no more than three tumors (each measured < or = 7 cm, total tumor volume < or = 200 cm(3)). They were treated percutaneously under ultrasound or computed tomography (CT) guidance, with up to 10 mL of CDDP-EPI gel (1 mL contains 4 mg of CDDP and 0.1 mg of EPI) per treatment and four treatments in 6 weeks to a maximum of eight treatments. The primary end points were tumor response, defined by change of percentage of tumor necrosis according to CT criteria, and safety. Survival parameters were secondary end points. RESULTS: From June 1997 to April 2000, 58 patients (median age, 65 years) entered the study. All patients were assessable for safety, and 51 were assessable for efficacy. The median number of treatments was four (range, one to eight treatments). Objective response rate was 53% (27 of 51 patients), including 16 complete and 11 partial responses. Of the 27 responders, 14 (52%) subsequently developed progressive disease, but in most of them (93%), a new tumor arose at untreated liver sites. Median survival was 27 months (range, 18.4 to 35.7 months). The 1-, 2-, and 3-year survival rates were 79%, 56%, and 14% respectively. The procedure was well tolerated with only minor side effects. CONCLUSION: Percutaneous local ablation with CDDP-EPI injectable gel can induce significant tumor necrosis and local control for localized unresectable HCC, and the treatment is well tolerated.

Adult↗
PubMed2003

[Importance of CT and MRI in the follow-up of patients with rectal cancer].

INDICATION: Presentation and evaluation of diagnostic procedures for the follow-up in patients with suspected local recurrence of rectal cancer. METHODS: Follow-up usually is performed using endoscopy and endosonography. Imaging techniques applied are also contrast enema as well as helical CT,MR imaging (MRI), and positron emission tomography (PET). RESULTS: The results demonstrate the difficulty of all available modalities to differentiate between early tumor recurrences from post-therapeutic alterations. Especially the differentiation of scar tissue and local tumor recurrence, the detection of lymph node as well as pulmonary or hepatic metastasis requires a large diagnostic effort with employment of various imaging modalities. Values determined for sensitivity and specificity for CT are 84% and 91% with a positive predictive value (PPV) of 78%. For MRI and PET the sensitivity are 94% and 98%,and the specificity 92% and 90% with a PPV of 93% for the PET. CONCLUSION: The results demonstrate the increasing importance of CT and MRI in the follow-up of patients with rectal cancer and enable an accurate and early diagnosis through employment of new examination strategies and sequence protocols.PET remains an add-on examination in uncertain local lesions.

Aged↗
PubMed2003

[Diagnostic imaging and differential diagnosis of pathological processes of the sinus cavernosus].

To describe the different imaging modalities for the evaluation of pathological changes in the cavernous sinus as well as to compile criteria for differential diagnosis. Imaging of the cavernous sinus comprises the primary use of tomographic modalities such as CT or MRI. The continuing development of multislice-CT (MSCT) allows the depiction of bony structures of the cavernous sinus with a high resolution.Secondary reconstructions of the acquired data set allow a reliable evaluation especially of the bony topography including the foraminae of nerves and vessels. Uni- or bilateral structures can be visualized using contrast-enhanced CT.CT-angiography is capable of demonstrating the course of the internal carotid artery and its involvement in pathologies of the cavernous sinus, this recent achievement has only been made available by use of the current short scanning times. Contrast-enhanced MRI in axial and coronal orientation, optionally using fat saturation techniques as well as arterial and venous MRI-angiography (MRA) are used to depict the soft parts of the cavernous sinus. Care must be taken to cover all topographic detail including different signal intensities, as multiple inborn, neoplastic, infectious or traumatic changes can be present hampering the radiologic diagnosis of the cavernous sinus. Uni- and bilateral infiltration of the cavernous sinus as well as vascular involvement represent additional criteria leading to the differential diagnosis. The advent of dynamic sequences as well as diffusion and perfusion weighted MRI have broadened the spectrum of diagnostic modalities. Digital subtraction angiography as an invasive technique is used during therapeutic procedures such as the local treatment of aneurysms or carotid-cavernous fistulas.

Carotid Artery, Internal↗
PubMed2003

[Early detection of colorectal tumors: CT or MRI?].

Cancer screening is currently offered for the organs breast, prostate, cervix and colorectum. With progressing technique in computerized tomography (CT) and magnetic resonance imaging (MRI) the colorectum can be increasingly better assessed. Because in CT and MRI also other organs are imaged with the colorectum, a colorectal screening automatically becomes a multiorgan screening. CT and MRI protocols designed for early detection of colorectal tumors are presented and discussed with regard to monoorganscreening (in CT: low dose, no i.v. contrast) and multiorganscreening (in CT: diagnostic dose for neighboured organs with i.v. contrast). More information under http://www.multiorganscreening.org.

Colonic Polyps↗