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Thomas H Helbich

Publications and source records attributed to Thomas H Helbich.

27 records · Page 2Linked to original sources
PubMed2002

Histopathologic correlation of high-resolution magnetic resonance imaging of human cervical tissue samples at 3 tesla: validation of a technique.

RATIONALE AND OBJECTIVES: High-resolution magnetic resonance (HR-MR) images of human cervical tissue samples were correlated with low magnification histology to investigate the MR presentation of normal and pathologic anatomic structures in cervical tissue samples at 3T. METHODS: Tissue samples were obtained from five large loop excision of the transformation zone (LLETZ) cone biopsies and one surgical specimen. HR-MR images (3D-Spin Echo sequence: TR/TE: 1500/60 milliseconds, voxel size of 117 x 208 x 234 microm) and low magnification (5x) histology sections were acquired in the same anatomical planes and correlated. RESULTS: In vitro HR-MR imaging of cervical tissue samples correlated well with low magnification microscopic histology, demonstrating normal anatomy (epithelium and its mucus layer, connective tissue of the stroma, glands, blood vessels). In vitro HR-MR imaging adds information about tumor content and margins. CONCLUSIONS: High resolution MR imaging of cervical tissue samples assists in the identification of both normal structures and pathologic changes.

Biopsy↗
PubMed2002

3D versus 2D ultrasound: accuracy of volume measurement in human cadaver kidneys.

RATIONALE AND OBJECTIVES: Comparison of the accuracy of 3D and 2D ultrasound in assessing the volume of human cadaver kidneys. MATERIALS AND METHODS: Before autopsy the volume of 22 kidneys was assessed from a 3D data set after manually tracing organ contours (3D volumetry) and by applying a 3D ellipsoid formula both on a 3D data set and 2D images. Measurements by water-displacement served as the gold standard. RESULTS: 3D volumetry showed a mean absolute deviation of 31 mL (18.5%) compared with the mean gold standard measurement (168 mL), yielding a concordance correlation (Lin's rho(c) ) of 0.71. Calculation based on the ellipsoid formula revealed a mean absolute deviation of 37 mL (22.0%) when applied on the 3D data set (rho(c) = 0.65) and of 42 mL (25.0%) when applied on 2D images (rho(c) = 0.61). CONCLUSIONS: 3D volumetry showed a satisfactory concordance correlation and is superior to volume calculation based on the ellipsoid formula either applied to a 3D data set or to conventional 2D images in assessing the volume of human cadaver kidneys.

Aged↗
PubMed2002

Comparison of sitting versus prone position for stereotactic large-core breast biopsy in surgically proven lesions.

OBJECTIVE: Our purpose was to compare the two different body positions for stereotactic large-core breast biopsy with regard to sensitivity, specificity, and accuracy, as well as complication rate. SUBJECTS AND METHODS: Two hundred patients had large-core breast biopsy performed either in the prone (n = 100) or in the sitting (n = 100) position and subsequently underwent surgical resection. The histopathologic findings of large-core breast biopsy and surgery of all 200 patients were compared; sensitivity, specificity, and accuracy were calculated for both groups. Biopsy-associated complications were prospectively recorded for immediate and delayed events and for technical failures in both groups. RESULTS: Sensitivity (96%), specificity (100%), and accuracy (98%) were the same for both groups with two false-negative findings in each group. The two false-negative results in the sitting group were caused by vasovagal reactions, whereas those in the prone group were caused by technical failure and uncomfortable biopsy position. More statistically significant complications (seven vs four, p < 0.001) and vasovagal reactions (seven vs two, p < 0.0001) were seen in the sitting group. CONCLUSION: For performance of large-core breast biopsy, both the prone and sitting positions are reliable and accurate methods. However, vasovagal reactions that could potentially complicate biopsy were seen significantly more often in the sitting position.

Adult↗
PubMed2002

Stereotactic 11-gauge vacuum-assisted breast biopsy: a validation study.

OBJECTIVE: The aim of our study was to determine the false-negative rate of stereotactic 11-gauge vacuum-assisted biopsy in a validation study of lesions that had subsequent surgical excision. MATERIALS AND METHODS: Retrospective review was performed of 318 lesions that underwent stereotactic 11-gauge vacuum-assisted biopsy and subsequent surgical excision. A false-negative case was defined as a pathologically proven cancer in which stereotactic biopsy yielded benign results without atypia. Medical records, imaging studies, and histologic findings were reviewed. RESULTS: False-negative findings were encountered at stereotactic 11-gauge vacuum-assisted biopsy in 3.3% (7/214) of pathologically proven cancers. False-negative findings occurred in 3.5% (4/115) of malignant calcification lesions versus 3.0% (3/99) of malignant masses (p = 1.0). The seven false-negative findings included five Breast Imaging Reporting and Data System (BI-RADS) category 5 lesions that yielded benign results at biopsy, one BI-RADS category 4 mass that benign breast tissue, and one BI-RADS category 4 cluster of calcifications in which no calcifications were retrieved. The false-negative rate was 10.0% (6/60) for radiologists who performed 15 or fewer previous stereotactic vacuum-assisted biopsy procedures versus 0.6% (1/154) for radiologists who performed more than 15 previous stereotactic vacuum-assisted biopsy procedures (p = 0.002). CONCLUSION: Stereotactic 11-gauge vacuum-assisted biopsy had a false-negative rate of 3.3% that diminished to 0.6% with experience. All false-negative findings could be prospectively identified because of failure to sample calcifications or imaging-histologic discordance.

Adult↗