Modification of the hand-held Vscan ultrasound and verification of its performance for transvaginal applications.

PURPOSE: The purpose of this work was to validate a new clinical obstetrics and gynecology (OB-GYN) application for a hand-held ultrasound (US) device. We modified the smallest hand-held device on the market and tested the system for transvaginal (TV) use. This device was originally conceived for abdominal scanning only. METHODS: The validation involved 80 successive patients examined by the same operator: 25 obstetric and 55 gynecologic cases. US examination was performed transvaginally with two US systems: the hand-held Vscan (General Electrics; GE Vingmed Ultrasound; Norway) for which an intravaginal gadget TTGP-2010® (Troyano transvaginal gadget probe) was designed, and the Voluson 730 Expert (multifrequency transvaginal ultrasound of 3-9MHz; GE Healthcare, Milwaukee, WI, USA). We performed the same measurements with both US systems in order to confirm whether or not their diagnostic capability was similar. Quantitative difference in measurements between the systems was assessed, as well as the overall diagnostic detection rate and suitability for telemedicine. RESULTS: Regarding lesion visibility with Vscan, optimal distance was 8-16cm depending on the examination type, and the total detection rate was 98.7%. The exception was an ovarian endometrioma, diagnosed as a follicular cyst using the hand-held device. Assessment of reproducibility in 180 measurements showed that the measurements obtained with Vscan were 0.3-0.4cm lower than those obtained with the high resolution US device (Voluson 730 Expert). Nevertheless, Pearson's correlation coefficient was high for biparietal diameter (0.72) and gynecological (GYN) (0.99) measurements, and for overall correlation (0.997). Image transport on USB and SD-flash cards proved convenient for telemedicine. CONCLUSIONS: A novel TV application of a hand-held US device is demonstrated for OB-GYN. Heart, abdominal and obstetrics presets of the Vscan together with color-Doppler enable a detection capability comparable to that of a high-definition US device. The lower values of the measurements obtained by the hand-held device (by 0.3-0.4cm) must be taken into account, although they have no effect on its diagnostic capability.

Virtual sonography through the Internet: volume compression issues.

BACKGROUND: Three-dimensional ultrasound images allow virtual sonography even at a distance. However, the size of final 3-D files limits their transmission through slow networks such as the Internet. OBJECTIVE: To analyze compression techniques that transform ultrasound images into small 3-D volumes that can be transmitted through the Internet without loss of relevant medical information. METHODS: Samples were selected from ultrasound examinations performed during, 1999-2000, in the Obstetrics and Gynecology Department at the University Hospital in La Laguna, Canary Islands, Spain. The conventional ultrasound video output was recorded at 25 fps (frames per second) on a PC, producing 100- to 120-MB files (for from 500 to 550 frames). Processing to obtain 3-D images progressively reduced file size. RESULTS: The original frames passed through different compression stages: selecting the region of interest, rendering techniques, and compression for storage. Final 3-D volumes reached 1:25 compression rates (1.5- to 2-MB files). Those volumes need 7 to 8 minutes to be transmitted through the Internet at a mean data throughput of 6.6 Kbytes per second. At the receiving site, virtual sonography is possible using orthogonal projections or oblique cuts. CONCLUSIONS: Modern volume-rendering techniques allowed distant virtual sonography through the Internet. This is the result of their efficient data compression that maintains its attractiveness as a main criterion for distant diagnosis.

Small marker chromosomes in a series of 1,000 prenatal diagnoses by amniocentesis.

We diagnosed two small marker chromosomes in a series of 1,000 prenatal cytogenetic studies of amniotic fluid cells. Each of these chromosomes was analyzed with various staining techniques in order to determine its structure and the possible mechanism of its formation. On the basis of the results thus obtained and the familial nature of these abnormalities, we predicted phenotypically normal fetuses in both cases. Postnatal follow-up confirmed this. Notwithstanding the correct diagnoses made in these two cases, we feel that a more substantial body of literature on this type of anomaly must become available before it will be possible to give firm genetic counselling in such cases.

A rare case of de novo structural rearrangement of X chromosome diagnosed by amniocentesis.

A dicentric X chromosome was found in a female fetus during cytogenetic studies performed on amniotic cells. Blood samples from the parents showed normal karyotypes and the pregnancy was terminated. The mechanism for the formation of this 'de novo' rearrangement is discussed.