MANYETİK REZONANS GÖRÜNTÜLEMENİN VÜCUT ISISINA ETKİSİ

Öz

Manyetik rezonans (MR) inceleme esnasında hastalar statik, gradyan ve radyofrekans (RF) elektromanyetik alanlara maruz kalırlar. Radyofrekans enerjisinin absorbsiyonunun doku ısısı artışlarına neden olduğu düşünülmektedir. Bu çalışmada 1.5 T MR görüntüleme esnasında vücut ısında oluşabilecek değişikliklerin saptanması amaçlanmıştır. Çalışmaya 21 ile 62 yaşları arasında (ortalama yaş 39±11.6 yıl) 34 kadın, 30 erkek toplam 64 hasta alınmıştır. Hastanın koltuk altı ısıları dijital termometre kullanılarak çekim öncesi ve sonrasında ölçülmüştür. Hastaların çekim öncesi koltuk altı ısıları ortalama 36.0±0.5 (34.8-37.1) OC iken, çekim sonrası ölçülen koltuk altı ısıları ortalama 36.4±0.5 (35.4-37.3) OC olarak bulunmuştur. Ortalama vücut ısı artışı; 0.4 ±0.3 (0.0-1.4) OC ve ortalama vücut ısısı artışı yüzdesi %1.1±0.8 (0.0-3.8) olarak saptanmıştır. Vücut ısılarında saptanan bu artışın istatistiksel olarak anlamlı olduğu görülmüştür (p<0.001). Sonuçlarımız özellikle termoregulasyonun etkilendiği düşünülen hastalarda MR görüntülemeleri sırasında dikkatli olmak gerektiğini düşündürmektedir. Yüksek alan gücüne sahip MR görüntüleme yöntemlerinin termofizyolojik etkilerini inceleyen ileri çalışmaların yürütülmesi gerektiği kanaatindeyiz. Dr. Özgür TOSUN, Dr. Karabekir ERCAN, Dr. Mustafa KARAOĞLANOĞLU

Anahtar Kelimeler

• Manyetik Rezonans Görüntüleme
• radyofrekans enerjisi
• vücut ısısı

THE EFFECT OF MAGNETIC RESONANCE IMAGING ON BODY TEMPERATURE

Öz

Patients are exposed to static, gradient and radiofrequency (RF) electromagnetic fields during magnetic resonance (MR) imaging. RF energy is believed to lead increases in tissue temperatures. This study aimed to determine the alterations in body temperature during 1.5 T MR imagings. A total of 64 patients of whom 34 were females and 30 were males aged between 21-62 (mean age 39±11.6 years) were included in the study. Armpit temperatures were measured by using a digital thermometer before and after imagings. Mean armpit temperatures of the patients before imaging was 36.0±0.5 (34.8-37.1) OC, while it was found as 36.4±0.5 (35.4-37.3) OC after imaging. Mean body temperature rise was 0.4 ±0.3 (0.0-1.4) 0C and mean body temperature rise percent was 1.1 ±0.8% (0.0-3.8). The detected rise in body temperature was statistically significant (p<0.001). Our results suggest that it is necessary to be careful during MR imaging especially in patients in whom thermoregulation is believed to be affected. We assume that further studies evaluating thermophysiological effects of higher magnetic field MR imaging procedures should be conducted

Anahtar Kelimeler

• Magnetic resonance imaging
• radiofrequency energy
• body temperature

Kaynakça

1. 1. Shellock FG, Crues JV. MR Procedures: Biologic Effects, Safety, and Patient Care. Radiology 2004;232:635-652
2. 2. Shellock FG, Crues FV. Temperature changes Caused by MR imaging of the brainwith a head coil. AJNR 1988;9: 287-29
3. 3. Schaefer DJ. Safety aspects of radiofrequency power deposition in magnetic resonance. Magn Reson Imaging Clin N Am 1998; 6:775-789
4. 4. Shellock FG. Radiofrequency energy-induced heating during MR procedures: a review. J Magn Reson Imaging 2000; 12:30-36
5. 5. Morvan D, Leroy-Willig A, Jehenson P, Cuenod CA, Syrota A. Temperature changes induced in human muscle by radiofrequency H-1 coupling: measurement with an MR imaging diffusion technique. Radiology 1992; 185:871-874
6. 6. Shellock FG, Crues JV. Temperature, heart rate, and blood pressure changes associated with clinical MR imaging at 1.5 T Radiology 1987; 163:259-262
7. 7. Shellock FG, Crues JV. Temperature changes caused by clinical MR imaging of the brain at 1.5 tesla using a head coil. AJNR Am J Neuroradiol 1988; 9:287- 291
8. 8. Shellock FG, Rothman B, Sarti D. Heating of the scrotum by high-field-strength MR imaging. AJR Am J Roentgenol 1990; 154:12291232

9. 9. Shellock FG, Schatz CJ. Increases in corneal temperature caused by MR imaging of the eye with a dedicated local coil. Radiology 1992;185:697-699
10. 10. Shellock FG, Schaefer DJ, Crues JV. Alterations in body and skin temperatures caused by MR imaging: is the recommended exposure for radiofrequency radiation too conservative? Br J Radiol 1989;62:904-909
11. 11. Kangarlu A, Shellock FG, Chakeres D. 8.0-tesla MR system: temperature changes associated with radiofrequency-induced heating of a head phantom. J Magn Reson Imaging 2003;17:220-226
12. 12. Shellock FG, Schaefer DJ, Kanal E. Physiologic responses to MR imaging performed at an SAR level of 6.0 W/kg. Radiology 1994;192:865-868
13. 13. Schaefer DJ. Health effects and safety of radiofrequency power deposition associated with magnetic resonance procedures. In: Shellock FG, eds. Magnetic resonance procedures: health effects and safety. Boca Raton, Fla: CRC, 2001; 55-74
14. 14. Shellock FG, Schaefer DJ. Radiofrequency energy-induced heating during magnetic resonance procedures: laboratory and clinical experiences. In: Shellock FG, eds. Magnetic resonance procedures: health effects and safety. Boca Raton, Fla: CRC; 2001. p.75-96
15. 15. Gordon CJ. Normalizing the thermal effects of radiofrequency radiation: body mass ver- sus total body surface area. Bioelectromagnetics 1987;8:111-118
16. 16. Schaefer DJ, Barber BJ, Gordon CJ Thermal effects of magnetic resonance imaging (abstr) In: Book of abstracts: Society of Magnetic Resonance in Medicine 1985. Berkeley, Calif: Society of Magnetic Resonance in Medicine;1985. p.925
17. 17. Oh S, Webb AG, Neuberger T, Park B, Collins CM. Experimental and numerical assessment of MRI-induced temperature change and SAR distributions in phantoms and in vivo. Magn Reson Med 2010:63:21823
18. 18. Atkinson IC, Renteria L, Burd H, Pliskin NH, Thulborn KR. Safety of human MRI at static fields above the FDA 8-T guideline: sodium imaging at 9.4 T does not affect vita signs or cognitive ability. J Magn Reson Imaging 2007;26:1222-7
19. 19. Maehata AM, Willschke H, Kabon B, Grayer D, Marhofer P.Effect of brain magnetic resonance imaging on body core temperature in sedated infants and children. Br J Anaesth 2009;102:385-9
20. 20. Rowell LB. Cardiovascular aspects of human thermoregulation. Circ Res 1983; 52:367-379
21. 21. Drinkwater BL, Horvath SM. Heat tolerance and aging. Med Sci Sports 1979;11:49-55