Abstract
We compared Magnetic Resonance Imaging (MRI) and 3D Endoanal Ultrasound (EAUS) imaging performance to confirm anal carcinoma and to monitor treatment response.58 patients with anal cancer were retrospectively enrolled. All patients underwent clinical examination, anoscopic examination; EAUS and contrast-enhanced MRI study before and after treatment. Four radiologists evaluated the presence of lesions, using a 4-point confidence scale, features of the lesion and nodes on EAUS images, T1-weighted (T1-W), T2-weighted (T2-W) and diffusion-weighted images (DWI) signal intensity (SI), the apparent diffusion coefficient (ADC) map for nodes and lesion, as well as enhancement pattern during dynamic MRI were assessed.All lesions were detected by EAUS while MRI detected 93.1% of anal cancer. MRI showed a good correlation with EAUS, anoscopy and clinical examination. The residual tissue not showed significant difference in EAUS assessment and T2-W SI in pre and post treatment. We found significant difference in dynamic study, in SI of DWI, in ADC map and values among responder's patients in pre and post treatment. The neoplastic nodes were hypoecoic on EAUS, with hyperintense signal on T2-W sequences and hypointense signal on T1-W. The neoplastic nodes showed SI on DWI sequences and ADC value similar to anal cancer. We found significant difference in nodes status in pre and post therapy on DWI data.3D EAUS and MRI are accurate techniques in anal cancer staging, although EAUS is more accurate than MRI for T1 stage. MRI allows correct detection of neoplastic nodes and can properly stratify patients into responders or non responders.
Highlights
Anal carcinoma is a rare malignancy with an incidence of 2 new cases per 100,000 per year in the USA [1], accounting approximately 0.4% of all tumors and 2.5% of gastrointestinal malignancies [2,3,4]
Magnetic Resonance Imaging (MRI) showed a good correlation with Endoanal Ultrasound (EAUS), anoscopy and clinical examination when the stage was greater than T1: 2 (3.4%) were T2, 39 (67.2%) were T3, and 13 (22.4%) were T4
According to Kolev et al [23], that demonstrated that T category on 3-D EAUS correlated with histopathology in 92.9%, and N category correlated with histopathology in 81.6%, our results showed that 3D EAUS is a valuable diagnostic tool in the assessment of T stage, even for stage T1
Summary
Anal carcinoma is a rare malignancy with an incidence of 2 new cases per 100,000 per year in the USA [1], accounting approximately 0.4% of all tumors and 2.5% of gastrointestinal malignancies [2,3,4]. Proper recognition of the anal cancer is crucial for the patient management, whereas an early detection allows conservative treatment with a reserve of sphincter function [9]. According to National Comprehensive Cancer Network (NCCN) Anal Carcinoma Guidelines the patients should be subjected to a careful clinical examination, including a digital rectal examination (DRE), an anoscopic examination, and palpation of inguinal nodes, to evaluate T stage, while the role of Computed Tomography (CT) and Magnetic Resonance Imaging (MRI) is limited to the identification of regional nodes, the endoanalultrasound (EAUS) is not recommended [12]. It is easy to perform and to reproduce, painless, with high diagnostic accuracy It provides excellent imaging of the anal wall, of the internal and external sphincters and of the intersphincteric plane, essential for planning surgical approach [13]. MR imaging plays an important role in therapeutic assessment, properly stratify patients into responders or non-responders to neoadjuvant treatment, in surveillance after surgery, and in recurrence [15,16]
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