Quantitative Non-Gaussian Intravoxel Incoherent Motion Diffusion-Weighted Imaging Metrics and Surgical Pathology for Stratifying Tumor Aggressiveness in Papillary Thyroid Carcinomas.

David Aramburu Núñez,Ashok R Shaha,R Michael Tuttle,Hilda E Stambuk,Vaios Hatzoglou,Andre L Moreira,Amita Shukla-Dave,Yonggang Lu,Ronald A Ghossein,Yousef Mazaheri,Jung Hun Oh,Ramesh Paudyal,Mithat Gonen

doi:10.18383/j.tom.2018.00054

Abstract

We assessed a priori aggressive features using quantitative diffusion-weighted imaging metrics to preclude an active surveillance management approach in patients with papillary thyroid cancer (PTC) with tumor size 1–2 cm. This prospective study enrolled 24 patients with PTC who underwent pretreatment multi-b-value diffusion-weighted imaging on a GE 3 T magnetic resonance imaging scanner. The apparent diffusion coefficient (ADC) metric was calculated from monoexponential model, and the perfusion fraction (f), diffusion coefficient (D), pseudo-diffusion coefficient (D*), and diffusion kurtosis coefficient (K) metrics were estimated using the non-Gaussian intravoxel incoherent motion model. Neck ultrasonography examination data were used to calculate tumor size. The receiver operating characteristic curve assessed the discriminative specificity, sensitivity, and accuracy between PTCs with and without features of tumor aggressiveness. Multivariate logistic regression analysis was performed on metrics using a leave-1-out cross-validation method. Tumor aggressiveness was defined by surgical histopathology. Tumors with aggressive features had significantly lower ADC and D values than tumors without tumor-aggressive features (P < .05). The absolute relative change was 46% in K metric value between the 2 tumor types. In total, 14 patients were in the critical size range (1–2 cm) measured by ultrasonography, and the ADC and D were significantly different and able to differentiate between the 2 tumor types (P < .05). ADC and D can distinguish tumors with aggressive histological features to preclude an active surveillance management approach in patients with PTC with tumors measuring 1–2 cm.

Highlights

Many clinicians continue to recommend an aggressive initial management approach to all but the patients with the most low-risk papillary thyroid carcinoma (PTC), which usually includes thyroid surgery and radioactive iodine adjuvant therapy [1]
The recommendations for either a limited thyroid surgery option or an active surveillance management approach may be less-drastic incremental options for patients with intrathyroidal papillary thyroid cancers thought to be at low risk for disease-specific mortality and recurrence
Studies have shown that patients with micropapillary carcinomas having small tumors well confined to the thyroid and without presence of extrathyroidal extension and/or lymph node metastases are good candidates for active surveillance [2]

Summary

Introduction

Many clinicians continue to recommend an aggressive initial management approach to all but the patients with the most low-risk papillary thyroid carcinoma (PTC), which usually includes thyroid surgery and radioactive iodine adjuvant therapy [1]. The recommendations for either a limited thyroid surgery option (thyroid lobectomy without adjuvant therapy) or an active surveillance management approach (serial observation with neck ultrasonography [US] with surgical intervention deferred until documented disease progression) may be less-drastic incremental options for patients with intrathyroidal papillary thyroid cancers thought to be at low risk for disease-specific mortality and recurrence. These treatment options are being offered on the basis of abundance of data showing excellent clinical outcomes following either thyroid lobectomy or active. Some experts have suggested that additional imaging methods be used to verify the absence of disease outside the thyroid when considering a conservative management approach in larger tumors

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