Early radiation-induced changes evaluated by intravoxel incoherent motion in the major salivary glands.
OBJECTIVE
To investigate the potential of intravoxel incoherent motion (IVIM) MRI for early evaluation of irradiated major salivary glands.


METHODS
Thirty-four patients with head-neck cancer were included in a prospective study. All patients underwent three serial IVIM-MRI: before, half-way through, and at the end of radiotherapy (RT). Apparent diffusion coefficient (ADC), ADClow derived in the low b-value range, perfusion fraction f, and pure diffusion coefficient D were estimated. Pretreatment values and early changes of diffusion parameters were correlated with parotid mean dose (Dmean ) and volume reduction after RT.


RESULTS
Changes in diffusion parameters over time were all significant (P < 0.001 for ADC, ADClow , and D, P = 0.003 for f). Variations of ADC, ADClow , and f were not correlated with Dmean (P = 0.089, P = 0.252 and P = 0.884, respectively), whereas a significant relationship was found between changes in D and Dmean (r = 0.197 with CI95% = 0.004-0.375, P = 0.046). Pretreatment f and Dmean were the best independent predictors for the percentage shrinkage (P = 0.0003 and 0.0597 respectively; R(2) = 0.391).


CONCLUSIONS
Early changes of irradiated major salivary glands can be noninvasively evaluated by IVIM-MRI. Perfusion-related coefficients in conjunction with dosimetric information increase our capability to predict the change in parotid volume and hence, if further validated, guide treatment strategy in RT.
Medical Physics Laboratory, Regina Elena National Cancer Institute, Rome, Italy.
Simona
S
Marzi
Chiara
C
Forina
Laura
L
Marucci
Giuseppe
G
Giovinazzo
Carolina
C
Giordano
Francesca
F
Piludu
Valeria
V
Landoni
Giuseppe
G
Spriano
Antonello
A
Vidiri
D000328:Adult; D000368:Aged; D000465:Algorithms; D005260:Female; D006258:Head and Neck Neoplasms / Q000150:complications / Q000473:pathology / Q000532:radiotherapy*; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009038:Motion; D020266:Radiotherapy, Conformal / Q000009:adverse effects*; D015203:Reproducibility of Results; D012466:Salivary Gland Diseases / Q000209:etiology* / Q000473:pathology*; D012680:Sensitivity and Specificity
diffusion-weighted imaging; intravoxel incoherent motion imaging; quantitative imaging; radiotherapy; salivary glands