Biomedical subjects

Panos Prassopoulos

Publications and source records attributed to Panos Prassopoulos.

22 records · Page 2Linked to original sources

PubMed2002

Comparison of two volumetric techniques for estimating liver volume using magnetic resonance imaging.

PURPOSE: To compare the conventional technique of manual planimetry with the point counting technique for estimating liver volume from magnetic resonance imaging (MRI) data. MATERIALS AND METHODS: This study comprised abdominal MR examinations of 38 consecutive patients. Evaluation of the images showed that liver size appeared normal in 27 patients and increased in 11. Liver volume was estimated using the techniques of planimetry and point counting. Both techniques were used in combination with the Cavalieri method of modern design stereology. A systematic slice sampling procedure was performed to estimate liver volumes using both volumetric techniques. The point counting technique was optimized by altering the point spacing of the grid. The agreement between the two techniques was found. Measurement repeatability of both volumetric techniques was also evaluated. RESULTS: Both techniques allowed the same degree of optimization through the procedure of systematic section sampling. The application of a point spacing of 2.5 cm reduced the time measurement by a factor of 3.5 in relation with the time needed with planimetry. An excellent agreement was observed between the two volumetric techniques with mean differences (+/-SD) of 2.4 +/- 41.6 cm(3) and 8.5 +/- 49.8 cm(3) for the patients presenting normal and increased liver sizes, respectively. Both techniques were highly reproducible. CONCLUSION: The point counting technique could be considered a more efficient approach than planimetry for estimating liver volume from MRI, due to its speed and simplicity.

Adult↗

PubMed2002

Arteriovenous malformation of the neck presented during delivery.

Vascular anomalies in the head and neck area are not infrequent and, in most cases, are congenital in origin. We present a congenital arteriovenous malformation (AVM) of the neck that manifested in a young woman during delivery. Imaging findings on ultrasonography (US), computed tomography (CT) and angiography were inconclusive and the diagnosis was reached by magnetic resonance imaging. A total excision of the mass was performed.

Adult↗

PubMed2002

Technical challenges and clinical applications of magnetic resonance enteroclysis.

With the advent of gradient systems the image quality of ultrafast pulse sequences, i.e., half Fourier acquisition single shot turbo spin echo (HASTE), true fast imaging with steady-state processing and fast low angle shot (FLASH), improved substantially and clinical applications including small bowel imaging became feasible. Within this context, magnetic resonance enteroclysis was developed as a comprehensive examination of the small bowel, providing luminal, transmural, and exoenteric diagnostic information of small bowel abnormalities. Clinical applications of magnetic resonance enteroclysis include diagnostic evaluation and follow-up of patients with inflammatory or neoplastic diseases and small bowel obstruction.

Contrast Media↗

PubMed2002

Transtympanic iontophoresis with a biocompatible paramagnetic solution at MR imaging: experimental feasibility study in rabbits.

PURPOSE: To determine the feasibility of transtympanic iontophoresis in experimental animals with a paramagnetic contrast agent at magnetic resonance (MR) imaging. MATERIALS AND METHODS: Optimal MR sequence parameters and appropriate paramagnetic ion concentrations of a water and gadopentetate dimeglumine solution were initially assessed with phantoms. Iontophoresis was performed in left ears of five rabbits after the external auditory canals were filled with a solution of water and gadopentetate dimeglumine of optimal concentration, and right ears were used as controls. Signal-to-structural noise ratio (SSNR) and contrast-to-structural noise ratio (CSNR) were measured by using regions of interest, and the overall image quality was assessed subjectively. RESULTS: Spin-echo (SE) MR sequences were superior to gradient-echo (GRE) MR sequences in terms of SSNR, CSNR, and overall image quality. Highest SSNR and CSNR values were achieved with 2 mmol/L (2 mM) of gadopentetate dimeglumine solution with both SE (repetition time msec/echo time msec, 500/12; flip angle, 90 degrees ) and GRE (300/10; flip angle, 90 degrees ) sequences in both phantoms and animals. The high signal intensity of gadopentetate dimeglumine solution was recognized in middle ears, vestibules, and semicircular canals of all rabbit ears that had undergone iontophoresis and in none of the control ears. CONCLUSION: With the solution of water and gadopentetate dimeglumine, the maximum SSNR and CSNR with both SE and GRE MR imaging sequences were achieved. The solution can be transferred to the middle and inner ear cavities across an intact tympanic membrane by using transtympanic iontophoresis.

Animals↗