Use of Imaging to Predict Complete Response of Colorectal Liver Metastases after Chemotherapy: MR Imaging versus CT Imaging

Abstract

Purpose To compare the diagnostic performances of contrast agent-enhanced computed tomography (CT) and gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid-enhanced liver magnetic resonance (MR) imaging (referred to as EOB MR imaging) in the evaluation of disappearing colorectal liver metastases (CRLMs) after chemotherapy. Materials and Methods The eight institutional review boards approved this retrospective study and waived the requirement for informed consent. On the basis of retrospective searches in eight hospitals, 87 patients with 393 CRLMs, each patient with one or more CRLM that later disappeared on contrast-enhanced CT scans after chemotherapy, and subsequently underwent surgery for the CRLMs, were enrolled. The anonymized imaging data and case report forms were sent to the central review system and independently reviewed by four radiologists. All anonymized data were randomly allocated into two groups (groups A and B), which were read by two independent readers. True absence of tumor was defined as pathologic absence of tumor for resected lesions and no in situ recurrence within 1 year after surgery for lesions left unresected at each 3-month follow-up contrast-enhanced CT. Positive predictive values for absence of tumor and for residual tumor on contrast-enhanced CT and EOB MR images were compared by using a generalized estimating equation. Results Among 393 CRLMs, the positive predictive value for absence of tumor on EOB MR images (78.0%; 95% confidence interval [CI]: 63.68%, 87.74%) was significantly higher than that on contrast-enhanced CT scans (35.2%; 95% CI: 25.11%, 46.79%; P < .001). The positive predictive value for residual tumor on CT scans (86.0%; 95% CI: 78.61%, 91.16%) was higher than that on EOB MR images (83.8%; 95% CI: 77.50%, 88.67%) without statistical significance (P = .330). Conclusion EOB MR imaging was superior to contrast-enhanced CT imaging for assessment of disappearing CRLMs after chemotherapy. RSNA, 2017 Online supplemental material is available for this article.

Gadolinium-Based Contrast Agents in Kidney Disease: A Comprehensive Review and Clinical Practice Guideline Issued by the Canadian Association of Radiologists

“… 48 , 49 Gadoxetate disodium–enhanced MRI is also more accurate when compared with conventional MRI and CT for confirmation of radiologic complete response of liver metastases (“disappearing metastases”). 50 The usefulness of gadoxetate disodium for diagnosis of FNH versus HCA has recently been found to be less than previously reported, 51 and the patient population for which these diagnoses are considered are generally young healthy female patients where AKI or severe renal impairment is not anticipated. Therefore, a clinical situation where gadoxetate disodium is required to evaluate for FNH versus HCA in AKI or severe renal impairment is unlikely.…”

Imaging in disappearing colorectal liver metastases and their accuracy: a systematic review

“…After chemotherapy, no standard imaging protocol was used preoperatively, to evaluate response to chemotherapy and identify DLM although CE-CT was used as a reference or baseline in most patients. In six studies [8,9,14,15,21,23], all patients were evaluated with both CE-CT and MRI preoperatively. Types of imaging used before and after chemotherapy are presented in detail in Table 3.…”

“…According to preoperative imaging, a DLM on CE-CT was equal to a CR in 17-69% (median 51%) and 40-85% (median 78%) according to MRI. There were 3 studies specifically comparing CE-CT with EOB-MRI, and all of them showed that EOB-MRI was significantly more superior in detecting the DLM with CR [8,9,21]. In 4 studies where DLM on preoperative CE-CT were additionally evaluated with MRI and IOUS [8,9,21,23], these remaining undetectable DLM were equal to a CR in 75-94% (median 89%).…”

“…There were 3 studies specifically comparing CE-CT with EOB-MRI, and all of them showed that EOB-MRI was significantly more superior in detecting the DLM with CR [8,9,21]. In 4 studies where DLM on preoperative CE-CT were additionally evaluated with MRI and IOUS [8,9,21,23], these remaining undetectable DLM were equal to a CR in 75-94% (median 89%). In 3 of these studies, addition of IOUS to MRI significantly improved detection of the DLM with CR [8,21,23] while in one the benefit was negligible [9].…”

“…In 4 studies where DLM on preoperative CE-CT were additionally evaluated with MRI and IOUS [8,9,21,23], these remaining undetectable DLM were equal to a CR in 75-94% (median 89%). In 3 of these studies, addition of IOUS to MRI significantly improved detection of the DLM with CR [8,21,23] while in one the benefit was negligible [9]. Regarding detectability of CRLM, in the [8,9], all the remaining CRLM that were identified by preoperative CE-CT were also identified by MRI and IOUS.…”