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Erschienen in:
01.02.2013 | Head and Neck
Diffusion-weighted MR imaging including bi-exponential fitting for the detection of recurrent or residual tumour after (chemo)radiotherapy for laryngeal and hypopharyngeal cancers
Erschienen in: European Radiology | Ausgabe 2/2013
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Objectives
To assess whether diffusion-weighted magnetic resonance imaging (DW-MRI) including bi-exponential fitting helps to detect residual/recurrent tumours after (chemo)radiotherapy of laryngeal and hypopharyngeal carcinoma.
Methods
Forty-six patients with newly-developed/worsening symptoms after (chemo)radiotherapy for laryngeal/hypopharyngeal cancers were prospectively imaged using conventional MRI and axial DW-MRI. Qualitative (visual assessment) and quantitative analysis (mono-exponentially: total apparent diffusion coefficient [ADCT], and bi-exponentially: perfusion fraction [FP] and true diffusion coefficient [ADCD]) were performed. Diffusion parameters of tumour versus post-therapeutic changes were compared, with final diagnosis based on histopathology and follow-up. Mann-Whitney U test was used for statistical analysis.
Results
Qualitative DW-MRI combined with morphological images allowed the detection of tumour with a sensitivity of 94% and specificity 100%. ADCT and ADCD values were lower in tumour with values 120 ± 49 × 10−5 mm2/s and 113 ± 50 × 10−5 mm2/s, respectively, compared with post-therapeutic changes with values 182 ± 41 × 10−5 mm2/s (P < 0.0002) and 160 ± 47 × 10−5 mm2/s (P < 0.003), respectively. FP values were significantly lower in tumours than in non-tumours (13 ± 9% versus 31 ± 16%, P < 0.0002), with FP being the best quantitative parameter for differentiation between post-therapeutic changes and recurrence.
Conclusions
DW-MRI in combination with conventional MRI substantially improves detection and exclusion of tumour in patients with laryngeal and hypopharyngeal cancers after treatment with (chemo)radiotherapy on both qualitative and quantitative analysis, with FP being the best quantitative parameter in this context.
Key Points
• DW-MRI is increasingly used to detect tumour recurrence.
• DW-MRI allows accurate post-treatment recurrence detection in laryngeal or hypopharyngeal cancer
• ADC values in recurrent tumour are lower than in benign tissue alterations
• Both qualitative and quantitative DW-MRI approaches allow detection of recurrence
• DW-MRI can easily be added to daily clinical routine imaging