## 1 Introduction  
The third most common cancer and the third leading cause of oncological death in the United States and Europe is the colorectal cancer [1; 2]. Total mesorectal excision (TME) following neoadjuvant chemo-radiation therapy (CRT) is the gold standard for locally advanced rectal cancer (LARC) treatment [3]. One concern after surgery is the local recurrence rate, which although recently improved, is still relevant [4]. Local recurrence in patients with rectal cancer undergoing surgical resection has an incidence of 2.6-30% [5; 6]. Total mesorectal excision has standardized the surgical technique in treating primary rectal cancer and has significantly reduced the local colorectal cancer recurrence (LCR) rate from 30% to 10% [6]. [PERSON] et al. reported that the rectal cancer local recurrences incidence within five years was 6% and 13%, respectively, for patients who received preoperative CRT and postoperative CRT (\(p=0.006\)) [3]. Pelvic Magnetic Resonance Imaging (MRI) is a standard diagnostic tool in the follow-up of patients with previous rectal cancer and in case of suspicious of local recurrence. In some patients, the presence of a prescalar lesion cannot be sufficiently characterized solely using traditional MRI techniques (T1, T2, etc.). Moreover, small tumors within fibrotic scar tissues are difficult to detect [7]. Several researchers have suggested diffusion-weighted imaging (DWI) to assess treatment response [7; 8; 9; 10; 11; 12]. Furthermore, [PERSON] et al. [7] as well as [PERSON] et al. [13] have shown the DWI potential as an additional tool for local rectal cancer recurrence detection. DWI measures the random Brownian water molecules motion, which is linked to cell density, cell membrane integrity, vascularity, and the viscosity of extracellular fluid [14; 15]. These properties can be quantified by means of the individual apparent diffusion coefficient (ADC) using a mono-exponential model or by means of diffusion and perfusion tissue features using a bi-exponential model derived by Intravoxel Incoherent Motion method (IVIM). The IVIM allows the calculation of the pure tissue diffusion coefficient (Dt) that describes water motion in the cellular interstitial space, the pseudo-diffusion coefficient (Dp) that describes blood microscopic flow in the vessels, and the perfusion fraction (fp) that describes the proportion of the diffusion motion [10; 11; 12; 13; 14; 15; 16; 17]. The conventional DWI model is based on the assumption that water diffusion follows a Gaussian behavior where water molecules diffuse without any [18]. However, water molecules diffusion within biologic tissues shows non-Gaussian behavior due to the presence of microstructures [18]. [PERSON] and co-workers proposed a non-Gaussian diffusion model named diffusion kurtosis imaging (DKI) [18]. Using this model, it is possible the extraction of the kurtosis coefficient (K), that measures the deviation of tissue diffusion from a Gaussian model, and the diffusion coefficient (D) with the correction of non-Gaussian bias. The added value of DWI in the prediction and assessment of tumor response to neoadjuvant CRT in patients with rectal cancer was demonstrated by several authors [7; 8; 9; 10; 11; 12; 13; 14; 15; 16; 17; 18; 19; 20; 21; 22; 23]. Moreover, [PERSON] et al. [24] assessed the value of ADC in the differentiating of locally recurrent rectal cancer from scar tissue demonstrating that ADC had high accuracy. They, therefore, concluded that Diffusion weighted MRI by means of ADC allows the differentiation of tumor recurrence from scar tissue after surgical resection of rectal cancer. To our knowledge, until now, there have been no studies published comparing IVIM and DKI derived parameters with the aim to evaluate their potential in the differentiation of local colorectal cancer recurrence from scar/fibrosis tissue in patients that underwent to TME after CRT for locally advanced rectal cancer (LARC).