Читать книгу Handbook of MRI Technique - Catherine Westbrook - Страница 31

The CNR is defined as the difference in SNR between two adjacent areas. It is controlled by the same factors that affect SNR. All examinations should include images that demonstrate a good CNR between pathology and surrounding normal anatomy so that pathology is well visualized. The CNR between pathology and other structures can be increased by the following:

 administration of contrast agents

 utilization of T2‐weighted pulse sequences

 suppression of normal tissues or pulse sequences that null signal from certain tissues e.g., short TI inversion recovery (STIR), fluid alternated inversion recovery (FLAIR) and magnetization‐prepared pulse sequences

 use of pulse sequences that enhance flow (see Pulse sequences).