Yazar "Yilmaz, U. N." seçeneğine göre listele

Listeleniyor 1 - 2 / 2
  • [ X ]
    Öğe
    MR T1 and T2 relaxations in cysts and abscesses measured by 1.5 T MRI
    (British Inst Radiology, 2012) Yilmaz, U. N.; Yaman, F.; Atilgan, S. S.
    Objectives: The main objective of this study was to make a comparison between the relaxation rates in jaw cysts and abscesses. Such a comparison should provide quantitative information for MR image analysis. Methods: A phantom containing 20 odontogenic jaw cysts and 11 jaw abscesses was imaged with 1.5 T MR. T-1 measurements were performed by using a mixed sequence of inversion recovery and spin echo, while T-2 measurements were carried out by the Carr-Purcell Meiboom-Gill (CPMG) sequence. Cystic fluids and abscesses were compared statistically. Results: In cysts and abscesses, respectively, the mean 1/T-1 was 0.9355 s(-1) and 0.8245 s(-1) and the mean 1/T-2 was 2.4575 s(-1) and 4.7073 s(-1). The 1/T-2 in cysts was very highly significantly different from that in abscesses (p = 0.0001). Both T-1 and T-2 were linearly proportional to material contents. T-2 relaxivities [26.458 ml(g s)(-1) for abscesses and 21.455 ml (g s)(-1) for cysts] were higher than T-1 relaxivities [5.4766 ml (g s)(-1) for abscesses and 10.075 ml (g s)(-1) for cysts]. Discussion: Present T-2 measurements differentiate cysts from abscesses with a confidence interval of 95%. Because in vivo and in vitro image contrasts are changed by the same parameters, the T-2 findings should present valuable information for in vivo MRI. Hence the significant difference and the relaxivities may provide quantitative information for clinicians and researchers making image analyses. Conclusion: T-2 may differentiate cysts from abscesses. The difference in T-2 is related to the material content of samples. Dentomaxillofacial Radiology (2012) 41, 385-391. doi: 10.1259/dmfr/96188015
  • [ X ]
    Öğe
    Shortening of NMR 1/T1 and 1/T2 Relaxation Rate Distribution Intervals in D2O Containing Jaw Cysts or Abscesses: Separation of Cysts from Abscesses
    (Springer, 2020) Yilmaz, U. N.; Yilmaz, B. D.
    It is well known that the relaxation rates (1/T-1 and 1/T-2) in H2O/D2O mixtures are smaller than those in H2O alone. The results of this have not been examined in the presence of a low rate of cysts or abscess contents in D2O. One purpose of this study was to determine the shortening of the relaxation rate distribution interval (SRDI) for D2O containing cysts or abscess contents. Another goal is to investigate the differentiation of cysts from abscesses with T-1 and T-2 measurements. The ultimate objective is the possibility of a new MRI contrast mechanism for dental lesions. Nineteen odontogenic jaw cysts and 12 jaw abscesses were collected from patients. A mixture was prepared by adding 0.06 mL cyst or abscess content to 0.94 mL D2O. The experiments were carried out with a nuclear magnetic resonance spectrometer operating at 400 MHz. The mean 1/T-2 of the abscesses was significantly different from that of the cysts (P < 0.005), but the mean 1/T-1 of the non-haemorrhagic cysts was not different from that of the abscesses (P = 0.626). The interval shortening ratios (SRDIs) of 1/T-1 and 1/T-2 for the cystic mixture were 16.36 and 4.22, respectively. The ratios were 8.39 and 2.68, respectively, for the mixture containing abscess contents. In conclusion, the relaxation rate reduction of the mixture results in a shortening of the distribution intervals, which leads to the separation of cysts from abscesses. In addition, the high interval shortening ratios indicate that the results of this study can provide a basis for studies on a new MR contrast mechanism for jaw lesions.