Biomedical subjects

Jens Ricke

Publications and source records attributed to Jens Ricke.

25 records · Page 2Linked to original sources

PubMed2003

Dual-energy chest radiography with a flat-panel digital detector: revealing calcified chest abnormalities.

OBJECTIVE: The aim of this study was to assess the value of dual-energy chest radiography obtained using a cesium iodide flat-panel detector in addition to standard posteroanterior chest radiography for the detection of calcified chest abnormalities. MATERIALS AND METHODS: The study included 20 patients with a total of 37 calcified chest lesions (16 pulmonary nodules, 17 mediastinal calcifications, and four pleural calcifications) as confirmed on CT. Twenty-eight locations in the chests of the same patients who were free of lesions were used as negative controls. Four radiologists reviewed posteroanterior chest radiographs in a blinded manner alone and in conjunction with dual-energy soft-tissue and bone images. We calculated sensitivity, specificity, the negative predictive value (NPV), and the positive predictive value (PPV) for lesion prediction. The Wilcoxon's and the Brunner and Langer's tests were performed for statistical analysis. RESULTS: For posteroanterior chest radiography, sensitivity was 36%, the PPV was 64%, and the NPV was 47%. When dual-energy images were added, sensitivity increased significantly to 66% (p < 0.05), the PPV to 76%, and the NPV to 62%. The specificity remained constant at 73%. Brunner and Langer's test revealed a highly significant difference between posteroanterior chest radiography and dual-energy imaging in the detection of calcified chest abnormalities (p < 0.01). CONCLUSION: Dual-energy images added to standard posteroanterior chest radiographs significantly improve the detection of calcified chest lesions.

Aged↗

PubMed2002

Prospective evaluation of contrast-enhanced MRI in the depiction of peritoneal spread in primary or recurrent ovarian cancer.

The purpose of this study was to assess the accuracy of MRI in the staging of intra-abdominal tumor seeding of ovarian carcinoma. Fifty-seven patients with suspected primary or recurrent ovarian carcinoma were included in this study. All patients received laparotomy within 8 weeks after MRI. The MRI protocol included fat-saturated T1-weighted spin-echo (SE) sequences pre- and post i.v. application of gadopentetate dimeglumine. The criteria for tumor manifestation was contrast enhancement of intra-abdominal soft tissue lesions or peritoneum. The image review was performed by a blinded radiologist, a specialist in gynecological and abdominal MR imaging. Results were compared with findings during laparotomy. Sensitivity, specificity, positive and negative predictive values, and corresponding 95% confidence intervals were calculated for single intra-abdominal locations and for groups of locations defined according to surgical strategies for intra-abdominal cytoreduction. Laparotomy and histopathology confirmed 251 abdominal tumor locations. Sensitivity was high in lower pelvis locations (73-83%) except for ureter or bladder infiltration (40%). Bowel or mesentery locations displayed sensitivity values from 73 to 77%. Sensitivity was very low for pelvic lymph nodes (28%), greater omentum (38%), and lesser sac (43%). Magnetic resonance imaging based on contrast-enhanced fat-saturated T1 SE sequences improves planning of cytoreduction preceding chemotherapy in advanced primary or relapsed ovarian carcinoma.

Abdominal Neoplasms↗

PubMed2002

Flat panel digital radiography compared with storage phosphor computed radiography: assessment of dose versus image quality in phantom studies.

RATIONALE AND OBJECTIVE: To assess and quantify the dose reduction by use of a CsI-flat panel digital radiography (DR)-system compared with digital computed radiography (CR). MATERIALS AND METHODS: A TCDD-test using the CDRAD-phantom was performed at mAs-values of 5, 4, 2.5, 2, 1, and 0.5 mAs for both digital systems. Entrance surface doses were recorded for all images. Images were presented to four independent observers. For quantitative comparison the image quality figure (IQF) was calculated. Statistical analysis was performed using the Pearson correlation and the Wilcoxon test. A ROC analysis was performed using the TRG-phantom. Settings of 4, 2.5, 2 mAs for both systems were used. In addition, 1 and 0.5 mAs were used for the DR system only. Statistical significance was evaluated using Student test. RESULTS: The DR system provided equivalent results compared with CR with respect to high frequency information and superior results with respect to low contrast details. Compared with computed radiography, the flat panel detector demonstrated significantly lower IQFs, ensuring a better image quality with respect to contrast and detail detectability. IQFs for DR and CR were equal at a surface dose reduction of 87% for DR. ROC analysis revealed significantly higher values under the curve for DR up to a surface dose reduction of 70%. CONCLUSIONS: Image quality of DR proved to be far superior to CR in particular for low contrast details. The image quality of CR is similar to that of DR only at high dose levels.

Phantoms, Imaging↗

PubMed2002

Prospective evaluation of pancreatic tumors: accuracy of MR imaging with MR cholangiopancreatography and MR angiography.

PURPOSE: To prospectively assess accuracy of magnetic resonance (MR) imaging, MR cholangiopancreatography (MRCP), and MR angiography in patients suspected of having pancreatic tumors. MATERIALS AND METHODS: Sixty-six patients suspected of having pancreatic tumors underwent MR imaging (unenhanced and contrast material-enhanced MR, MRCP, and contrast-enhanced MR angiography). Two blinded readers prospectively analyzed the images by consensus, and results were correlated with surgery, biopsy, or follow-up findings. Results were tabulated in two-by-two tables. RESULTS: MR assessment of pancreatic lesion status (differentiation of benign vs malignant) resulted in 60 correct diagnoses (accuracy, 91%), and six (10%) false diagnoses. Among histologically proved malignant tumors, MR imaging yielded correct diagnoses in 42 of 44 patients (sensitivity, 95%; 95% CI: 85%, 99%), whereas 18 of 22 patients with benign findings were classified correctly. At MR imaging, findings in four patients with chronic pancreatitis were wrongly categorized as malignant tumors (specificity, 82%; 95% CI: 60%, 95%), and in one patient, a distal common bile duct carcinoma was not detected. In no patient with pancreatic adenocarcinoma was this tumor misdiagnosed as benign. In patients with malignant tumors who underwent resection, local-regional tumor growth and vascular infiltration were accurately classified in 89% and 94%, respectively. MR imaging depicted histologically proved synchronous hepatic metastases in 82%. The positive and negative predictive values for cancer nonresectability were 90% and 83%, respectively, and the accuracy, sensitivity, and specificity were 85%, 69%, and 95%, respectively. CONCLUSION: Unenhanced and contrast-enhanced MR imaging with MRCP and MR angiography offers potential as a noninvasive tool for assessment of patients suspected of having pancreatic tumors.

Adult↗

PubMed2002

[Using network planning techniques for work flow analysis in a clinical environment].

In the face of increasing financial pressure on our health care system, one way to reduce costs while maintaining or even improving outcome quality is to improve work flow efficiency. Network Planning Technique (NPT) is a tool for mapping and analyzing work flows. Designing a network plan requires four steps. Step 1 is concerned with the determination of the work flow structure. Step 2 deals with data acquisition. Based on the data retrieved a network plan is created in Step 3. Step 4 includes the calculation of the critical path and slack times under optimistic, realistic and pessimistic conditions. Applied to the ultrasound division in our department a total examination time of 34:14 minutes was calculated with 23:09 minutes total slack time for the technician under realistic conditions. Using NPT creates transparency in work flows and allows us to estimate resource demands. A comparison between two different divisions with a similar work flow structure but different resource allocation demonstrates this method's potential for improving work flows. Limitations of the NPT can be noted when considering cycle overlap in repetitive work flows and modeling non-regular activities.

Diagnosis-Related Groups↗

PubMedDate not supplied

Efficacy of contrast medium use for neuroimaging at 3.0 T: utility of IR-FSE compared to other T1-weighted pulse sequences.

As inversion-recovery (IR) technique improves T1 contrast at high field strength, signal enhancement by T1-shortening contrast media may be affected. To clarify the different enhancement properties at 3.0 T, the authors compared T1-weighted sequences. Twelve contrast-enhancing lesions were investigated by spin-echo (SE), inversion recovery fast spin-echo (IR-FSE), two-dimensional gradient-echo (2D GE), and magnetization-prepared three-dimensional gradient-echo (3D GE) sequences and evaluated by comparing signal-intensity enhancements within the lesions. In addition, signal-to-noise-ratios (SNR) and contrast-to-noise-ratios (CNR) were measured. On average, signal enhancement of the lesions amounted to 60% for SE, 57% for IR-FSE, 32% for 2D GE, and 35% for 3D GE images. CNR of gray matter versus white matter was significantly higher for IR SE and GE imaging than for genuine SE and 2D GE acquisitions (Wilcoxon test), while 2D GE imaging alone had an excellent SNR. As IR-FSE images provide an excellent CNR for gray and white matter in the brain and contrast enhancement performs almost similarly well compared with SE imaging, this technique appears to be well suited for T1-weighted neuroimaging without and with contrast enhancement at 3.0 T. However, the inherent blurring of the IR-FSE can lead to poor performance for very small lesions.

Adult↗

PubMedDate not supplied

Volume determination of intracranial aneurysms using 16-row multislice computed tomography angiography: a systematic in vitro analysis of different reconstruction methods.

OBJECTIVE: To assess multislice computed tomography (CT) angiography for volume determination of intracranial aneurysms. METHODS: Submillimetric 16-row multislice CT angiography was performed with optimized scan parameters on precision spheres and a soft carotid artery model harboring 3 aneurysms connected to a pulsatile circuit. The CT angiography images were produced using optimized techniques for axial, multiplanar reformation, maximum intensity projection, surface-shaded display, and volume-rendered images. Measurements were made with electronic precision calipers by segmentation according to the method of Cavalieri and by the use of automated volumetric analysis software. RESULTS: Segmentation resulted in precise and accurate volume estimates of aneurysms, but small volumes were underestimated and evaluation time was long (36:44 minutes). Automated volume evaluation from volume-rendered reconstructions also resulted in low measurement error, although the evaluation process was significantly faster (3:25 minutes; P < 0.0001). CONCLUSIONS: The use of an automated volume analysis tool on volume-rendered reconstructions is recommended for time-efficient volume assessment of intracranial aneurysms.

Carotid Arteries↗