Biomedical subjects

Masoom A Haider

Publications and source records attributed to Masoom A Haider.

22 records · Page 2Linked to original sources

PubMed2003

Manually respiratory-triggered single-shot fast spin-echo: a non-breath-hold T2-weighted method for liver lesion detection.

OBJECTIVES: To determine whether manual respiratory triggering of a T2-weighted single-shot fast spin-echo sequence (M-SSFSE) improves detection and characterization of liver lesions compared with conventional breath-held single-shot fast spin-echo (C-SSFSE) technique. METHODS: M-SSFSE is performed by manually triggering a series of single-slice acquisitions through the liver at end of expiration. There were 171 hepatic lesions in 49 patients. Images were randomized and reviewed by 3 radiologists. Lesions were characterized as hemangiomas, cystic or solid. Dynamic gadolinium-enhanced sequences were used as the reference standard. Contrast-to-noise ratios (CNR) were calculated for all lesions that measured 1 cm or more. RESULTS: M-SSFSE was more sensitive than C-SSFSE in the detection of liver lesions (48%-58% v. 37%-46%, p < 0.001). There were no significant differences in the specificity of lesion detection between the 2 sequences. Artifacts were significantly less severe for M-SSFSE compared with C-SSFSE (p = 0.001). The CNR was significantly higher for all liver lesions on M-SSFSE compared with C-SSFSE (p < 0.001). CONCLUSION: M-SSFSE significantly improved hepatic lesion detection and, in particular, improved characterization of solid liver lesions and hemangiomas compared with C-SSFSE imaging.

Adult↗

PubMed2002

Interobserver variation in postimplant computed tomography contouring affects quality assessment of prostate brachytherapy.

PURPOSE: Permanent seed implants are accepted treatment of early stage prostate cancer. Implant quality is assessed by post implant CT-based dosimetry but prostate contours on CT images are obscured by metallic seed artefact and edema. Outcome depends on implant quality, but perceived implant quality depends on accurate prostate contouring. This study documents inter observer variation in prostate contouring on post implant CT scans. METHODS AND MATERIALS: Ten patients had implant dosimetry calculated on 4 copies of the post implant CT scan. Prostate contours from MRI-CT fusion were the gold standard for prostate edge identification. CTs were contoured by an experienced prostate brachytherapist matching CT images to the pre implant TRUS, and by 2 GU radiation oncologists experienced in conformal radiotherapy planning. Dosimetry was compared to that obtained using MRI-CT fusion in terms of D90 and V100. RESULTS: Contours and dosimetry were not reproducible among the 3 observers. The V100's of the experienced brachytherapist differed from that of MRI-CT fusion by a mean of 2.4% compared to 9.1% and 4.4% for observers 1 and 2, and the D90 by a mean of 9.3 Gy compared to 30.3 and 14.4 Gy for observers 1 and 2. CONCLUSIONS: Quality assessment of prostate brachytherapy based on 1 month post implant CT is difficult. This may obscure the dose-response relationship in brachytherapy as well as create problems for quality assurance in multicentre trials evaluating brachytherapy against standard modalities. Whenever possible, MRI-CT fusion should be employed to verify prostate contours post implant.

Brachytherapy↗

PubMed2002

Multi-detector row helical CT in preoperative assessment of small (< or = 1.5 cm) liver metastases: is thinner collimation better?

PURPOSE: To determine the value of collimations less than 5 mm in detecting hepatic metastases 1.5 cm or smaller by using multi-detector row helical computed tomography (CT). MATERIALS AND METHODS: Thirty-one patients underwent contrast material-enhanced multi-detector row helical CT before hepatic resection in this prospective study. Images were reconstructed at collimations of 5.00, 3.75, and 2.50 mm with 50% overlap and reviewed independently by three radiologists. Each lesion was characterized as metastatic, benign, or equivocal and graded for conspicuity. Criterion standards were pathologic assessment of the resected liver and follow-up of the nonresected liver. Only lesions 1.5 cm or smaller were analyzed. RESULTS: There were a total of 88 liver lesions 1.5 cm or smaller, and 25 of these were metastases. Pooled sensitivity for all lesions improved with thinner collimation (66% [58 of 88 lesions], 69% [61 of 88], and 82% [72 of 88] at collimations of 5.00, 3.75, and 2.50 mm, respectively), and this was statistically significant (P =.01). However, no significant difference was noted between collimations in the pooled sensitivity for metastatic lesions (80% [20 of 25 lesions] at all collimations) (P >.99). No statistical difference was noted in the conspicuity of lesions at different collimations (P =.18). CONCLUSION: Image reconstruction with multi-detector row helical CT at collimations less than 5 mm may not improve sensitivity in the detection of hepatic metastases 1.5 cm or smaller.

Adult↗

PubMedDate not supplied

Extending PowerPoint with DICOM image support.

Although PowerPoint has become a ubiquitous presentation tool in medical imaging, it does not support the Digital Imaging and Communications in Medicine (DICOM) standard. Users must go through a laborious conversion process that includes guessing the appropriate brightness and contrast to convert 16-bit DICOM images into 8-bit formats. A PowerPoint add-in was developed that incorporates features of a DICOM viewer into a presentation. Users can interactively manipulate large series of 16-bit images in stack mode with scroll, crop, zoom, and window width and level functions, as well as sort through images by location or series. Multiple DICOM image series can be placed on a single slide, and one can interactively scroll through stacks of images during a presentation to demonstrate imaging findings. The problem created by the varying contrast and brightness of different projector systems is overcome by interactively adjusting the image window level during presentations. Bone and lung window views can be shown without having to create separate images. Combining DICOM images into stacks as part of a PowerPoint presentation can result in a more effective and higher-quality presentation of medical images.

Data Display↗