Biomedical subjects

Thomas C Lauenstein

Publications and source records attributed to Thomas C Lauenstein.

41 records · Page 3Linked to original sources

PubMed2002

Optimization of contrast dosage for gadobenate dimeglumine-enhanced high-resolution whole-body 3D magnetic resonance angiography.

RATIONALE AND OBJECTIVES: To determine the optimal dose of gadobenate dimeglumine for diagnostic high-resolution whole-body 3D-MR angiography. METHODS: Ten healthy volunteers were examined three times with an ascending dose of Gd-BOPTA (0.1/0.2/0.3 mmol/kg BW). Three-dimensional data sets were collected with a rolling table platform (AngioSURF; MR-Innovation GmbH, Essen, Germany) which integrates the torso surface coil, using a 3D FLASH sequence at five stations from carotid arteries to the trifurcation vessels in 72 seconds. SNR- and contrast-to-noise-values were calculated for 30 segments per patient. For qualitative evaluation a 4-point-visualization scale was used. RESULTS: Overall, significantly (P < 0.05) higher signal-to-noise values and CNR values were determined for Gd-BOPTA at a dose of 0.2 and 0.3 mmol/kg compared with 0.1 mmol/kg. Similarly, the qualitative analysis demonstrated image quality to be superior with 0.2 and 0.3 mmol/kg compared with 0.1 mmol/kg (P < 0.05). Qualitative and quantitative assessment failed to demonstrate a statistically significant difference between 0.2 and 0.3 mmol/kg BW (P > 0.05). CONCLUSION: A dose of 0.2 mmol/kg BW Gd-BOPTA rendered diagnostic image quality in all vascular segments of all volunteers.

Adult↗

PubMed2002

Contrast-enhanced magnetic resonance imaging (MS-325) in a murine model of systemic lupus erythematosus.

RATIONALE AND OBJECTIVES: To investigate whether inflammatory activity can be evaluated by MRI with an intravascular compound (MS-325) in Desoxyribonuclease I (Dnase1)-deficient mice, which show classical symptoms of systemic lupus erythematosus. METHODS: Dnase1-deficient and normal mice (both groups n = 10) underwent MRI with a body weight adapted dose of MS-325 on a 1.5 T whole body scanner equipped with a dedicated surface coil. MR images of the kidneys and the aorta and signal to noise ratios prior and post contrast administration were compared with histopathology in all animals. RESULTS: Dnase1-knockout mice demonstrated aortic-wall enhancement and inhomogeneous-renal enhancement with significantly higher SNR values corresponding to microscopically proved inflammatory changes (P < 0.05). CONCLUSION: MS-325-enhanced MRI appears to be a sensitive tool for the detection of renal and vascular involvement in this animal model. In addition, this method may facilitate assessment of therapeutic approaches in patients with SLE in the future.

Animals↗

PubMed2002

MR colonography with barium-based fecal tagging: initial clinical experience.

PURPOSE: To assess a strategy for fecal tagging with barium sulfate as an inexpensive tagging agent in conjunction with magnetic resonance (MR) colonography in patients suspected of having colorectal lesions. MATERIALS AND METHODS: Twenty-four patients suspected of having colonic lesions because of rectal bleeding, positive fecal occult blood test results, or altered bowel habits underwent MR colonography and subsequent conventional colonoscopy. A 200-mL dose of a barium sulfate-containing contrast agent was ingested with each of four low-fiber meals, beginning 36 hours before the examination. For MR colonography, the colon was filled with tap water. Gadobenate dimeglumine was injected intravenously. Images were acquired 75 seconds after gadobenate dimeglumine administration by using only a T1-weighted three-dimensional gradient-echo sequence. Images were reviewed by two radiologists blinded to conventional colonoscopic data. By using colonoscopy as the reference standard, sensitivity and specificity of MR colonography were determined for detecting colorectal masses. RESULTS: On the basis of MR colonography, 15 polyps of 5-20 mm and 10 carcinomas were detected and later confirmed with conventional colonoscopy. Conventional colonoscopy depicted three additional lesions less than 8 mm in diameter. Thus, sensitivity of MR colonography was 89.3% (25 of 28) for lesions and 91.7% (22 of 24) for patients. CONCLUSION: Barium-tagged MR colonography obviates bowel cleansing and depicts all lesions exceeding 8 mm in diameter.

Adult↗

PubMed2002

Three-dimensional volumetric interpolated breath-hold MR imaging for whole-body tumor staging in less than 15 minutes: a feasibility study.

OBJECTIVE: The purpose of our study was to evaluate the feasibility and accuracy of three-dimensional (3D) volumetric interpolated breath-hold whole-body MR imaging using CT and nuclear medicine techniques as the standard of reference in patients with metastases. CONCLUSION: The 3D volumetric interpolated breath-hold whole-body MR imaging examination for metastases screening correlates well with CT and scintigraphy. The use of the rolling table platform permits rapid whole-body imaging in an average of 11 min. The preliminary results indicate that the described technique has the potential to emerge as an all-encompassing alternative to conventional multimodality tumor staging strategies.

Adult↗

PubMed2002

Interstitial MR lymphography with MS-325: characterization of normal and tumor-invaded lymph nodes in a rabbit model.

OBJECTIVE: The aim of our study was to evaluate the performance of a new blood-pool contrast agent, MS-325, in depicting regional lymph nodes when injected interstitially and in allowing the subsequent classification of the lymph nodes as normal or tumor-bearing (VX2 tumor). MATERIALS AND METHODS: Six New Zealand white rabbits underwent adapted fast three-dimensional (3D) MR imaging before implantation of VX2 tumor cells in the flank and again 3 weeks after the implantation. For each imaging session, 0.5 mL of undiluted MS-325 was injected subcutaneously into both dorsal foot pads. For more than 120 min, the rabbits underwent repeated 3D MR imaging. The size of the individual lymph nodes and the amount of contrast agent uptake in the nodes were measured 5, 10, 15, 30, 60, and 120 min after the injection. After the rabbits had been sacrificed, their lymph nodes were removed and histopathologically analyzed. RESULTS. In normal as well as tumor-bearing hindlegs, the subcutaneous administration of MS-325 resulted in rapid delineation of popliteal, inguinal, iliac, and paraaortal lymph nodes. Tumor invasion into lymph nodes presented as circumscribed signal voids in the areas infiltrated by tumor, whereas the surrounding residual lymphatic tissue showed enhancement identical to that of normal nodes. CONCLUSION: In addition to providing a safe means of displaying the normal lymphatic system, MS-325-enhanced 3D MR lymphography depicts direct tumor invasion in lymph nodes.

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