Search PubMed⌕ Search

Biomedical subjects

G Srinivasan

Publications and source records attributed to G Srinivasan.

76 records · Page 5Linked to original sources
PubMedDate not supplied

Segmentation of gated Tl-SPECT images and computation of ejection fraction: a different approach.

BACKGROUND: We describe a set of image processing algorithms and mathematical models that can be advantageously used in schemes for the segmentation of thallium-201-single photon emission computed tomography (SPECT) images and for computation of left ventricular ejection fraction (EF). METHODS: The system consists of two independent blocs for image segmentation and computation of function. The former is based on a multiresolution elliptical coordinate transformation and dynamic contour tracking. Computation of EF is formulated on the basis of both the endocardial and epicardial contours, and we compare this formulation with that using only the endocardial border for images with low signal-to-noise ratios. The accuracy of border detection was validated against manual border tracing on FDG-PET images, simulated Tl-201-SPECT images where the true underlying borders were known, and actual Tl-201-SPECT images. Finally, we compared EFs computed for FDG-PET, technetium-99m-SPECT and Tl-201-SPECT with those obtained from planar gated blood pool imaging. RESULTS: The automatically obtained results always were within the manual uncertainty range. Agreement between myocardial volumes from positron emission tomography and automatically obtained values from the simulated Tl-201-SPECT images was excellent (r = 0.95, n = 32). Agreement between EFs from planar gated blood pool imaging and the other image modalities was good (FDG-PET: y = 5.89 + 1.21x, r = 0.92, see = 6.24, n = 19, Tc-99m-SPECT: y = -3.86 + 1.06x, r = 0.88, see = 7.78, n = 9, Tl-201-SPECT: y = 17.8 + 0.81x, r = 0.77, see = 7.44, n = 26). For noisy input data the combined use of information from epicardial and endocardial contours gives more accurate EF values than the traditional formula on the basis of the endocardial contour only. CONCLUSIONS: Alternate approaches for segmentation and computation of function have been presented and validated. They might also be advantageously incorporated into other existing techniques.

Algorithms↗
PubMedDate not supplied

Congenital syphilis: a diagnostic and therapeutic dilemma.

Seventy-eight newborn infants born to mothers with serologic evidence of syphilis (positive serum rapid plasma reagin and fluorescent treponemal antibody-absorption tests) were prospectively evaluated to derive diagnostic and therapeutic criteria for congenital syphilis. Sixty-one infants were asymptomatic with normal serum IgM and normal roentgenograms (Group I). Eight infants had clinical and/or laboratory evidence of infection at birth (Group II). Nine infants presented with late onset infection (Group III). Elevated serum IgM and abnormal roentgenologic findings were consistently present in symptomatic infants in Groups II and III. Cerebrospinal fluid (CSF) examination was normal in all asymptomatic infants and in all infants with late onset disease. One of the eight infants in Group II examined at birth had positive CSF Venereal Disease Research Laboratory determinations, but all other CSF findings were within normal limits, and a second infant with a slight increase in CSF protein had no clinical evidence of central nervous system (CNS) involvement. Of those asymptomatic infants who returned for follow-up 75% and 100% were seronegative by 3 and 6 months, respectively. The symptomatic infants remained seropositive up to 18 months of age. Infants who had no clinical evidence of CNS involvement at birth remained normal at follow-up and had normal CSF findings. The two infants with CNS symptoms at birth continued to have developmental delay despite normal CSF findings. The incidence of CNS involvement in congenital syphilis appears to be extremely low. The value of routine spinal fluid examination is discussed.

Fluorescent Antibody Technique↗