Hentschel M, Wust P, Fähling H, Richter R, Vogl T, Semmler W, Wolf K J, Felix R
Strahlenklinik und Poliklinik, Virchow-Klinikum, Medizinische Fakultät der Humboldt-Universität zu Berlin.
Strahlenther Onkol. 1996 Nov;172(11):610-8.
Phosphorus spectroscopy can be used to assess response in tumor therapy and to monitor response. An additional response parameter would be useful for individualization in oncological therapy. Methodical problems of localisation and contamination make it more difficult to interpret and reproduce the spectra. Interstitial and endoluminal spectroscopy antennas placed directly within or close to the tumor could provide help in this problem.
We developed an interstitial 31P MRS antenna together with a tuning network which can be used in thermometry catheters for hyperthermia within an internal lumen of 1.1 mm in diameter. A prototype of this type of miniature antenna suitable for use in Siemens MRI scanners at 1.5 T was described spectroscopically with regard to excitation profile, range and SNR.
In terms of quality, the excitation profiles of the interstitial antennas in relation to orientation correspond to those of comparable but considerably larger endocavitary antennas and catheter coils for MR imaging and spectroscopy. Maximum sensitivity was achieved by aligning the coil normal perpendicular to the B0 field. Signal losses of up to 50% have to be reckoned with when using other orientations. The maximum range of the interstitial antenna was determined using spectroscopy and was found to be 5 mm, i.e. 9 times coil radius. The sensitivity (SNR, detection sensitivity) of the studied type of interstitial antenna allows in vivo 31P spectroscopy to be performed despite the unusually low axial dimension (coil radius r = 0.55 mm). The prototype of the described interstitial antenna was used to measure an in vivo spectrum from the back muscle of a rabbit in 10 min. Nevertheless, the detection volume of at least some ml necessary for 31P spectroscopy results mainly from the large antenna length.
The sensitivity (SNR, detection sensitivity) of the interstitial antenna needs to be further improved in order to assess treatment response in patients. However, the construction principle is suitable for intracavitary 31P spectroscopy antenna with larger diameters, which can be used for advanced rectal, cervical and prostate carcinomas.
磷谱可用于评估肿瘤治疗反应并进行监测。额外的反应参数对于肿瘤治疗的个体化将是有用的。定位和污染方面的方法学问题使得光谱的解释和重现更加困难。直接置于肿瘤内部或靠近肿瘤的间质和腔内光谱天线可能有助于解决这一问题。
我们开发了一种间质31P磁共振波谱天线以及一个调谐网络，该天线可用于直径为1.1毫米的内腔内热疗的测温导管。从激发轮廓、范围和信噪比方面对这种适用于1.5T西门子磁共振成像扫描仪的微型天线原型进行了光谱描述。
在质量方面，间质天线相对于方向的激发轮廓与用于磁共振成像和波谱的可比但大得多的腔内天线和导管线圈的激发轮廓相对应。通过将线圈法线垂直于B0场对齐可实现最大灵敏度。使用其他方向时必须考虑高达50%的信号损失。使用波谱法确定间质天线的最大范围为5毫米，即线圈半径的9倍。尽管轴向尺寸异常小（线圈半径r = 0.55毫米），所研究类型的间质天线的灵敏度（信噪比、检测灵敏度）仍允许进行体内31P波谱分析。所描述的间质天线原型用于在10分钟内测量兔背部肌肉的体内光谱。然而，31P波谱分析所需的至少几毫升的检测体积主要源于天线的大长度。
为了评估患者的治疗反应，间质天线的灵敏度（信噪比、检测灵敏度）需要进一步提高。然而，其构造原理适用于更大直径的腔内31P波谱天线，可用于晚期直肠癌、宫颈癌和前列腺癌。
