Incremental value of liver MR imaging in patients with potentially curable colorectal hepatic metastasis detected at CT: a prospective comparison of diffusion-weighted imaging, gadoxetic acid-enhanced MR imaging, and a combination of both MR techniques

Role of gadoxetic acid-enhanced MRI in the differential diagnosis of chemotherapy-induced focal nodular hyperplasia-like lesions and liver metastases in patients with colorectal cancer

PURPOSE

To describe the gadoxetic acid-enhanced magnetic resonance imaging (MRI) features and follow-up changes of hepatic focal nodular hyperplasia (FNH)-like lesions induced by chemotherapy in patients with colorectal cancer (CRC) and the differential diagnosis of FNH-like lesions and liver metastases.

METHODS

We retrospectively analyzed the data of patients with CRC who received chemotherapy and gadoxetic-enhanced MRI at our hospital. Based on imaging features and pathological findings, the patients were classified into two groups: FNH-like lesions and liver metastases. Two abdominal radiologists reviewed and compared the signal intensities of all images in each phase for both groups. The characteristics of the FNH-like lesions in the hepatobiliary phase were evaluated, and changes in size of lesions were monitored.

RESULTS

Thirty patients with 82 FNH-like lesions and 30 with 49 liver metastases following chemotherapy were included in the study. All MRI findings were statistically significantly different between the two groups (p < 0.05). In FNH-like lesions, three enhancement patterns were observed in the hepatobiliary phase: hyperintense/isointense (18.3%), heterogeneous hyperintense (8.5%), and ring-like enhancement (73.2%). The median time from completion of chemotherapy to development of FNH-like lesions was 31 months. During 4-87 months of follow-up, 27 patients with 73 lesions showed the following outcomes: 41 lesions (56.16%) showed stability, 21 lesions (28.77%) growth, and 11 lesions (15.07%) reduction or disappearance.

CONCLUSION

Gadoxetic acid-enhanced MRI can distinguish between chemotherapy-induced FNH-like lesions and liver metastases in patients with CRC. The FNH-like lesions exhibited three enhancement patterns in the hepatobiliary phase, and the changes varied during follow-up.

Non-enhanced abbreviated MRI as a periodic surveillance protocol for colorectal liver metastases compared with contrast-enhanced CT: a prospective observational study

BACKGROUND

Adopting an appropriate noninvasive radiological method is crucial for periodic surveillance of liver metastases in colorectal cancer (CRC) patients after surgery, which is closely related to clinical management and prognosis. This study aimed to prospectively enroll stage II-III CRC patients for the surveillance of liver metastases and compare the diagnostic performance of contrast-enhanced CT (CE-CT) and non-enhanced abbreviated MRI (NE-AMRI) during this process.

METHODS

587 CRC patients undergoing radical resection of the primary tumor were evaluated by 1 to 3 rounds of surveillance tests, consisting of abdominal CE-CT and contrast-enhanced MRI (CE-MRI) within 7 days at 6-month intervals. Subsequently, images of NE-AMRI were extracted from the CE-MRI examination, and paired CE-CT and NE-AMRI analysis were performed. The lesion-based detection rates between two protocols were compared, and a subgroup analysis was performed in lesions with a size of ≤10 mm. The patient-based sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), accuracy, and the areas under the curves (AUCs) of CE-CT and NE-AMRI in each round were evaluated. Finally, the relationship between the diagnostic accuracy of two protocols and characteristics of patients was explored.

RESULTS

The lesion-based detection rates of NE-AMRI in three rounds were all significantly higher than those of CE-CT ( P < 0.001, P < 0.001, P = 0.003, respectively). In the subgroup analysis of lesions ≤ 10 mm, NE-AMRI also performed better than CE-CT ( P < 0.001, P = 0.002, P = 0.005, respectively). The patient-based sensitivities, specificities, NPVs, and PPVs of NE-AMRI were higher than those of CE-CT in three rounds of surveillance. The AUCs for NE-AMRI were all significantly better than those for CE-CT in each round ( P = 0.015, P = 0.045, P = 0.009, respectively). Furthermore, patient BMI and fatty liver disease had impacts on the diagnostic accuracy of the CE-CT protocol, but not on the NE-AMRI protocol.

CONCLUSION

NE-AMRI may be a promising periodic surveillance tool for CRC patients after surgery to increase diagnostic accuracy of liver metastases, developing personalized clinical management and improving prognosis, simultaneously avoiding side effects associated with ionizing radiation and contrast agents.

A Systematic Review of Disappearing Colorectal Liver Metastases: Resection or No Resection?

Background: Colorectal cancer is the second most common type of cancer and a leading cause of cancer-related deaths worldwide. Approximately 15% of the patients with colorectal cancer will already have liver metastases (CRLMs) at diagnosis. Luckily, the advances in chemotherapy regimens during the past few decades have led to increased rates of disease regression that could even render an originally unresectable disease resectable. In certain patients with CRLMs, the hepatic lesions are missing on preoperative imaging after neoadjuvant chemotherapy. These patients can undergo surgery with or without resection of the sites of the disappearing liver metastases (DLMs). In this systematic review, we assess the recurrence rate of the DLMs that were left unresected as well as the complete pathologic response of those resected. Methods: A literature search was conducted in PubMed for studies including patients with CRLMs who received neoadjuvant chemotherapy and had DLMs in preoperative imaging. Two independent reviewers completed the search according to the PRISMA checklist. Results: Three hundred and twenty-six patients with 1134 DLMs were included in our review. A total of 47 out of 480 DLMs (72.29%) that were removed had viable tumor cells in postoperative histology. One hundred and forty-five tumors could not be identified intraoperatively and were removed based on previous imaging, with thirty (20.69%) of them presenting viable cancer cells. Four hundred and sixty-five lesions could not be identified and were left in place. Of them, 152 (32.69%) developed local recurrence within 5 years. Of note, 34 DLMs could not be categorized as viable or non-viable tumors. Finally, DLMs that were identifiable intraoperatively had a higher possibility of viable tumors compared to non-identifiable ones (72.29% vs. 20.69%, respectively). Conclusions: Disappearing liver metastases that are left unresected have an increased possibility of recurrence. Patients receiving neoadjuvant treatment for CRLMs may have better survival chances after resecting all the DLM sites, either identifiable intraoperatively or not.

Photon-Counting CT Effects on Sensitivity for Liver Lesion Detection: A Reader Study Using Virtual Imaging

Background Detection of hepatic metastases at CT is a daily task in radiology departments that influences medical and surgical treatment strategies for oncology patients. Purpose To compare simulated photon-counting CT (PCCT) with energy-integrating detector (EID) CT for the detection of small liver lesions. Materials and Methods In this reader study (July to December 2023), a virtual imaging framework was used with 50 anthropomorphic phantoms and 183 generated liver lesions (one to six lesions per phantom, 0.4-1.5 cm in diameter). Virtual CT platforms simulated PCCT and EID CT scanners. Phantoms were virtually scanned using routine (6 mGy) and low-dose (1.5 mGy) conditions and reconstructed with three kernels. A subset of 300 scans (150 PCCT vs EID CT pairs) were selected. Four radiologists independently reviewed all scans to mark liver lesions, assigned confidence scores for detection, and rated scan quality. Analysis was performed on a per-lesion basis to determine sensitivity for several variables and on a per-scan basis for scan quality. The McNemar test, two-sided paired t tests, and mixed-effects logistic regression models were fitted; P < .05 was considered indicative of statistically significant difference. Results Consensus reader sensitivity in detecting lesions was 82.1% (451 of 549) for PCCT versus 77.6% (426 of 549) for EID CT (P < .001), with a mean sensitivity gain of 4.3 percentage points ± 1.3 (P < .001 to P = .02 per reader). Readers had better subjective confidence for lesions at PCCT (mean score, 61.5 ± 22 vs 56.1 ± 24 [on a 101-point scale]; P < .001). Sensitivity was lower for lesions smaller than 1 cm, with more pronounced difference between PCCT and EID CT (74.0% [271 of 366] vs 67.2% [246 of 366]; P < .001). At the lower dose level, PCCT showed higher sensitivity than EID CT (68.9% [168 of 244] vs 61.1% [149 of 244]; P < .001) for subcentimeter lesions. In a multivariable model, PCCT was independently associated with increased odds of lesion detection (odds ratio, 1.55; P < .001). Image quality was slightly higher for PCCT (mean score, 55.3 vs 50.6 [on a 101-point scale]; P < .001). Conclusion Compared with EID CT, PCCT showed better sensitivity in the detection of small liver lesions. © RSNA, 2025 Supplemental material is available for this article. See also the editorial by Menu in this issue.

Gadoxetic acid-enhanced MRI for the detection of liver metastases from melanoma

PURPOSE

We aimed to assess imaging findings and detection sensitivity for melanoma liver metastases on gadoxetic acid-enhanced magnetic resonance imaging (MRI).

METHODS

This retrospective study included patients with melanoma liver metastasis who underwent gadoxetic acid-enhanced MRI. Two abdominal radiologists independently evaluated signal characteristics of liver metastases on morphologic imaging (precontrast T1- and T2-weighted imaging), diffusion-weighted imaging (DWI), dynamic imaging, and hepatobiliary phase (HBP). Imaging findings were compared according to detection on HBP and the primary site of the melanoma using logistic regression with the generalized estimating equation (GEE). Detection sensitivity for metastases was compared among different MR imaging sets using logistic regression with GEE.

RESULTS

A total of 67 patients with 254 liver metastases were included (44 women; mean age ± standard deviation, 65.6 ± 13.0 years). On HBP, 76.0% of metastases were detected, and 55.5% (141/254) showed hypointensity. Most of the metastases that were not detected on HBP originated from ocular melanomas (98.4%, 60/61), ≤1 cm (90.2%, 55/61) and showed T1 hyperintensity (98.4%, 60/61). Metastases from non-ocular melanomas more frequently showed T1 hypointensity, T2 hyperintensity, diffusion restriction, arterial enhancement, and HBP hypointensity than those from ocular melanomas (Ps ≤ 0.019). The detection sensitivity of HBP (76.0%) was significantly higher than DWI (65.7%, P = 0.006), but lower than morphologic imaging (98.8%, P < 0.001) and dynamic imaging (97.6%, P < 0.001).

CONCLUSION

The detection sensitivity of HBP for melanoma liver metastasis was 76.0%, which was lower than that of morphologic or dynamic imaging. HBP of gadoxetic acid-enhanced MRI has little advantage in detecting melanoma liver metastases.

Detectability of Hypoattenuating Liver Lesions with Deep Learning CT Reconstruction: A Phantom and Patient Study

Background CT deep learning image reconstruction (DLIR) improves image quality by reducing noise compared with adaptive statistical iterative reconstruction-V (ASIR-V). However, objective assessment of low-contrast lesion detectability is lacking. Purpose To investigate low-contrast detectability of hypoattenuating liver lesions on CT scans reconstructed with DLIR compared with CT scans reconstructed with ASIR-V in a patient and a phantom study. Materials and Methods This single-center retrospective study included patients undergoing portal venous phase abdominal CT between February and May 2021 and a low-contrast-resolution phantom scanned with the same protocol. Four reconstructions (ASIR-V at 40% strength [ASIR-V 40] and DLIR at three strengths) were generated. Five radiologists qualitatively assessed the images using the five-point Likert scale for image quality, lesion diagnostic confidence, conspicuity, and small lesion (≤1 cm) visibility. Up to two key lesions per patient, confirmed at histopathologic testing or at prior or follow-up imaging studies, were included. Lesion-to-background contrast-to-noise ratio was calculated. Interreader variability was analyzed. Intergroup qualitative and quantitative metrics were compared between DLIR and ASIR-V 40 using proportional odds logistic regression models. Results Eighty-six liver lesions (mean size, 15 mm ± 9.5 [SD]) in 50 patients (median age, 62 years [IQR, 57-73 years]; 27 [54%] female patients) were included. Differences were not detected for various qualitative low-contrast detectability metrics between ASIR-V 40 and DLIR (P > .05). Quantitatively, medium-strength DLIR and high-strength DLIR yielded higher lesion-to-background contrast-to-noise ratios than ASIR-V 40 (medium-strength DLIR vs ASIR-V 40: odds ratio [OR], 1.96 [95% CI: 1.65, 2.33]; high-strength DLIR vs ASIR-V 40: OR, 5.36 [95% CI: 3.68, 7.82]; P < .001). Low-contrast lesion attenuation was reduced by 2.8-3.6 HU with DLIR. Interreader agreement was moderate to very good for the qualitative metrics. Subgroup analysis based on lesion size of larger than 1 cm and 1 cm or smaller yielded similar results (P > .05). Qualitatively, phantom study results were similar to those in patients (P > .05). Conclusion The detectability of low-contrast liver lesions was similar on CT scans reconstructed with low-, medium-, and high-strength DLIR and ASIR-V 40 in both patient and phantom studies. Lesion-to-background contrast-to-noise ratios were higher for DLIR medium- and high-strength reconstructions compared with ASIR-V 40. © RSNA, 2024 Supplemental material is available for this article.

Development and validation of a TRIM27-based nomogram for predicting metachronous liver metastasis and prognosis in postoperative colorectal cancer patients

BACKGROUND

Colorectal cancer ranks among the most prevalent malignancies globally. Accurate prediction of metachronous liver metastasis is crucial for optimizing postoperative management. Tripartite motif-containing protein 27 (TRIM27), an E3 ubiquitin ligase, is implicated in diverse cellular functions and tumorigenesis.

METHODS

This study aimed to develop and validate a TRIM27-based nomogram for prognostication in colorectal cancer patients. Transcriptome sequencing of five paired tumor and normal tissue samples identified TRIM27 as a potential prognostic biomarker. Immunohistochemistry was employed to assess TRIM27 expression in colorectal cancer cohorts from two institutions.

RESULTS

TRIM27 expression correlated significantly with both the prognosis of colorectal cancer patients and the occurrence of metachronous liver metastasis. A nomogram incorporating TRIM27 and clinical factors was constructed and demonstrated robust predictive accuracy in an independent validation cohort.

CONCLUSION

The TRIM27-based nomogram is a valuable prognostic tool for predicting prognosis and metachronous liver metastasis in colorectal cancer patients, aiding in personalized treatment decisions.

Utility of abbreviated MRI in the post-treatment evaluation of rectal cancer

BACKGROUND

Post-treatment evaluation of patients with rectal cancer (RC) using magnetic resonance imaging (MRI) burdens medical resources, necessitating an exploration of abbreviated protocols.

PURPOSE

To evaluate the diagnostic performance of abbreviated MRI (A-MRI) for the post-treatment evaluation of RC patients.

MATERIAL AND METHODS

This retrospective study included RC patients who underwent non-contrast rectal MRI and standard liver MRI, as well as abdominal contrast-enhanced computed tomography (CECT) for post-treatment evaluation. A-MRI comprised diffusion-weighted imaging (DWI) and T2-weighted imaging of the upper abdomen and the pelvic cavity. Three radiologists independently reviewed A-MRI, CECT, and standard liver MRI in the detection of viable disease. The diagnostic performances were compared using a reference standard considering all available information, including pathology, FDG-PET, endoscopic results, and clinical follow-up.

RESULTS

We included 78 patients (50 men, 28 women; mean age=60.9 ± 10.2 years) and observed viable disease in 34 (43.6%). On a per-patient-basis analysis, A-MRI showed significantly higher sensitivity (95% vs. 81%, P = 0.04) and higher accuracy (93% vs. 82%, P < 0.01), compared to those of CECT, while A-MRI showed comparable sensitivity (91% vs. 91%, P = 0.42) and accuracy (97% vs. 98%, P = 0.06) to that of standard liver MRI. On a per-lesion-based analysis, A-MRI exhibited significantly superior lesion detectability than that of CECT (figure of merit 0.91 vs. 0.77, P < 0.01) and comparable to that of standard liver MRI (figure of merit 0.91 vs. 0.92, P = 0.75).

CONCLUSION

A-MRI exhibited higher sensitivity and diagnostic accuracy than those of CECT in the post-treatment evaluation of RC, while it showed comparable performances with standard liver MRI. A-MRI provides diagnostic added value in the follow-up of RC patients.

Ablation of Small Liver Metastases Presenting as Foci of Diffusion Restriction on MRI-Results from the Prospective Minimally Invasive Thermal Ablation (MITA) Study

PURPOSE

Liver metastases presenting as small hyperintense foci on diffusion-weighted imaging (DWI) pose a therapeutic challenge. Ablation is generally not possible since these lesions are often occult on ultrasound and CT. The purpose of this prospective study was to assess if small liver metastases (≤10 mm) detected on DWI can be successfully localized and ablated with the Hepatic Arteriography and C-Arm CT-Guided Ablation technique (HepACAGA).

MATERIALS AND METHODS

All consecutive patients with small liver metastases (≤10 mm), as measured on DWI, referred for ablation with HepACAGA between 1 January 2021, and 31 October 2023, were included. Re-ablations and ablations concomitant with another local treatment were excluded. The primary outcome was the technical success rate, defined as the intraprocedural detection and subsequent successful ablation of small liver metastases using HepACAGA. Secondary outcomes included the primary and secondary local tumor progression (LTP) rates and the complication rate.

RESULTS

A total of 15 patients (26 tumors) were included, with liver metastases from colorectal cancer (73%), neuro-endocrine tumors (15%), breast cancer (8%) and esophageal cancer (4%). All 26 tumors were successfully identified, punctured and ablated (a technical success rate of 100%). After a median follow-up of 9 months, primary and secondary LTP were 4% and 0%, respectively. No complications occurred.

CONCLUSION

In this proof-of-concept study, the HepACAGA technique was successfully used to detect and ablate 100% of small liver metastases identified on DWI with a low recurrence rate and no complications. This technique enables the ablation of subcentimeter liver metastases detected on MRI.

Added Value of Liver MRI in Patients Eligible for Surgical Resection or Ablation of Colorectal Liver Metastases Based on CT: A Systematic Review and Meta-Analysis

Background

Abdominal computed tomography (CT) is the standard imaging modality for detection and staging in patients with colorectal liver metastases (CRLM). Although liver magnetic resonance imaging (MRI) is superior to CT in detecting small lesions, guidelines are ambiguous regarding the added value of an additional liver MRI in the surgical workup of patients with CRLM. Therefore, this systematic review and meta-analysis aimed to evaluate the clinical added value of liver MRI in patients eligible for resection or ablation of CRLM based on CT.

Methods

A systematic search was performed in the PubMed, Embase, and Cochrane Library databases through June 23, 2023. Studies investigating the impact of additional MRI on local treatment plan following CT in patients with CRLM were included. Risk of bias was assessed using the QUADAS-2 tool. The pooled weighted proportions for the primary outcome were calculated using random effect meta-analysis.

Results

Overall, 11 studies with 1440 patients were included, of whom 468 patients (32.5%) were assessed for change in local treatment plan. Contrast-enhanced liver MRI was used in 10 studies, including gadoxetic acid in 9 studies. Liver MRI with diffusion-weighted imaging was used in 8 studies. Pooling of data found a 24.12% (95% confidence interval, 15.58%-32.65%) change in the local treatment plan based on the added findings of liver MRI following CT. Sensitivity analysis including 5 studies (268 patients) focusing on monophasic portal venous CT followed by gadoxetic acid-enhanced liver MRI with diffusion-weighted imaging showed a change of local treatment plan of 17.88% (95% confidence interval, 5.14%-30.62%).

Conclusions

This systematic review and meta-analysis found that liver MRI changed the preinterventional local treatment plan in approximately one-fifth of patients eligible for surgical resection or ablation of CRLM based on CT. These findings suggest a clinically relevant added value of routine liver MRI in the preinterventional workup of CRLM, which should be confirmed by large prospective studies.

Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy for Peritoneal Metastases from Colorectal Cancer-An Overview of Current Status and Future Perspectives

Peritoneal metastases (PM) are observed in approximately 8% of patients diagnosed with colorectal cancer, either synchronously or metachronously during follow-up. PM often manifests as the sole site of metastasis. PM is associated with a poor prognosis and typically shows resistance to systemic chemotherapy. Consequently, there has been a search for alternative treatment strategies. This review focuses on the global evolution of the combined approach involving cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) for the management of PM. It encompasses accepted clinical guidelines, principles for patient selection, surgical and physiological considerations, biomarkers, pharmacological protocols, and treatment outcomes. Additionally, it integrates the relevant literature and findings from previous studies. The role of CRS and HIPEC, in conjunction with other therapies such as neoadjuvant and adjuvant chemotherapy, is discussed, along with the management of patients presenting with oligometastatic disease. Furthermore, potential avenues for future development in this field are explored.

MRI with DWI improves detection of liver metastasis and selection of surgical candidates with pancreatic cancer: a systematic review and meta-analysis

OBJECTIVE

To perform a systematic review and meta-analysis to evaluate if magnetic resonance imaging (MRI) with diffusion weighted imaging (DWI) adds value compared to contrast-enhanced computed tomography (CECT) alone in the preoperative evaluation of pancreatic cancer.

METHODS

MEDLINE, EMBASE, and Cochrane databases were searched for relevant published studies through October 2022. Studies met eligibility criteria if they evaluated the per-patient diagnostic performance of MRI with DWI in the preoperative evaluation of newly diagnosed pancreatic cancer compared to CECT. Our primary outcome was the number needed to treat (NNT) to prevent one futile surgery using MRI with DWI, defined as those in which CECT was negative and MRI with DWI was positive for liver metastasis (i.e., surgical intervention in metastatic disease missed by CECT). The secondary outcomes were to determine the diagnostic performance and the NNT of MRI with DWI to change management in pancreatic cancer.

RESULTS

Nine studies met the inclusion criteria with a total of 1121 patients, of whom 172 had liver metastasis (15.3%). The proportion of futile surgeries reduced by MRI with DWI was 6.0% (95% CI, 3.0-11.6%), yielding an NNT of 16.6. The proportion of cases that MRI with DWI changed management was 18.1% (95% CI, 9.9-30.7), corresponding to an NNT of 5.5. The per-patient sensitivity and specificity of MRI were 92.4% (95% CI, 87.4-95.6%) and 97.3% (95% CI, 96.0-98.1).

CONCLUSION

MRI with DWI may prevent futile surgeries in pancreatic cancer by improving the detection of occult liver metastasis on preoperative CECT with an NNT of 16.6.

CLINICAL RELEVANCE STATEMENT

MRI with DWI complements the standard preoperative CECT evaluation for liver metastasis in pancreatic cancer, improving the selection of surgical candidates and preventing unnecessary surgeries.

KEY POINTS

• The NNT of MRI with DWI to prevent potential futile surgeries due to occult liver metastasis on CECT, defined as those in which CECT was negative and MRI with DWI was positive for liver metastasis, in patients with pancreatic cancer was 16.6. • The higher performance of MRI with DWI to detect liver metastasis occult on CECT can be attributed to an increased detection of subcentimeter liver metastasis.

Apparent Variation in Measurement Size of Colorectal Cancer Metastases to the Liver on Dual Contrast MRI

PURPOSE

The aim of this study was to formally investigate the apparent variation in lesion size of hepatic metastatic lesions from colorectal cancer on hepatobiliary phase (HBP) and dual contrast images of magnetic resonance imaging performed with both hepatobiliary and extracellular contrast agents.

METHODS

Patients with known colorectal carcinoma who had undergone dual contrast liver magnetic resonance imaging were identified in our institutional database. Metastatic lesions were measured semiautomatically on both HBP and dual contrast images with a custom software tool that automatically identifies the lesion edge and thereby the lesion diameter. Lesion measurements from both sets of images were compared with a Student t test and Bland-Altman analysis. Lesions were also measured on both HBP and dual contrast images by 2 fellowship-trained abdominal radiologists. Measurements from the software and radiologists were compared with a Student t test and Bland-Altman analysis; interreader agreement was evaluated with the intraclass correlation coefficient.

RESULTS

A total of 70 liver lesions in 39 patients was identified. Software-based measurements were significantly larger on HBP than dual contrast images ( P < 0.001), with a mean lesion size of 10.9 ± 4.2 mm for HBP and 10.5 ± 4.2 mm for dual contrast measurements. Radiologist-based measurements showed a similar trend, with HBP measurements being significantly larger than dual contrast measurements ( P < 0.001). Bland-Altman analysis indicated a mean bias ± 2 SD of +0.4 ± 1.6 mm for software-based measurements and +0.9 ± 2.9 mm and +0.7 ± 2.1 mm for readers 1 and 2, respectively. The intraclass correlation coefficient for interreader agreement was 0.9.

CONCLUSIONS

Both software-based and radiologist-based measurements of colorectal cancer liver metastases are significantly larger on HBP than dual contrast images. Based on these findings, we recommend that longitudinal assessment be performed consistently on either HBP or dual contrast phases to avoid introduction of avoidable variability.

Diagnostic Performance of Contrast Enhanced CT Alone or in Combination with (Non-)Enhanced MRI for Colorectal Liver Metastasis

RATIONALE AND OBJECTIVES

To compare the diagnostic performance of contrast enhanced CT (CE-CT), CE-CT combined with non-enhanced MRI (NE-MRI) or contrast enhanced MRI (CE-MRI) for colorectal liver metastasis (CRLM).

MATERIALS AND METHODS

Sixty-six colorectal cancer patients with 198 focal liver lesions who underwent preoperative abdominal CE-CT and MRI examinations were included respectively. The images were assessed independently by two readers in three protocols (1: CE-CT, 2: CE-CT+NE-MRI, 3: CE-CT+CE-MRI). The diagnostic performance of each protocol was analyzed by receiver operating characteristic (ROC) curve and the areas under ROC (AUCs) were calculated and compared.

RESULTS

The detection rates of protocol 2 were 90.9%-92.9% for liver lesions and 86.4%-89.6% for CRLM, and both significantly higher than protocol 1 of 82.8%-85.4% and 76.8%-80.8% (p<0.001-0.001), whereas similar to protocol 3 of 91.9%-94.4% and 87.2%-91.2% (p 0.250-1.000). The AUCs of protocol 2 were greater than protocol 1 for all lesions (0.914-0.934 vs. 0.779-0.799, p<0.001) and lesions < 10mm (0.726-0.776 vs. 0.528-0.561, p<0.001), and were not inferior to that of protocol 3 (0.929-0.949 in all lesions and 0.754-0.821 in lesion < 10mm, p 0.053-0.162).

CONCLUSION

CE-CT combined with NE-MRI offered superior diagnostic performance for CRLM compared to CE-CT alone and showed comparable performance to CE-CT combined with CE-MRI.

The application of abbreviated MRI protocols in malignant liver lesions surveillance

Cancer is one of the leading public health problems globally. Since time is of the essence in oncology, the sooner an accurate diagnosis is made, the better the prognosis for patients. There is a growing need to find a flawless and fast imaging method for cancer detection, but also for its evaluation during treatment. In this respect, the possibilities and novelties of magnetic resonance imaging are particularly promising. Abbreviated magnetic resonance imaging (AMRI) protocols have aroused universal interest as a compromise between scanning time reduction and preservation of image quality. Shorter protocols focused on the detection of suspicious lesions with the most sensitive sequences could provide a diagnostic performance similar to the one of the standard protocol. The purpose of this article is to review the ongoing accomplishments in the use of AMRI protocols in liver metastases and HCC detection.

Diagnostic performance of abbreviated gadoxetic acid-enhanced magnetic resonance protocols with contrast-enhanced computed tomography for detection of colorectal liver metastases

BACKGROUND

Although contrast-enhanced magnetic resonance imaging (MRI) using gadoxetic acid has been shown to have higher accuracy, sensitivity, and specificity for the detection and characterization of hepatic metastases compared with other modalities, the long examination time would limit the broad indication. Several abbreviated enhanced MRI (Ab-MRI) protocols without dynamic phases have been proposed to achieve equivalent diagnostic performance for the detection of colorectal liver metastases. However, an optimal protocol has not been established, and no studies have assessed the diagnostic performance of Ab-MRI combined with contrast-enhanced computed tomography (CE-CT), which is the preoperative imaging of colorectal cancer staging in clinical settings, to determine the best therapeutic strategy.

AIM

To compare the diagnostic performance of two kinds of Ab-MRI protocol with the standard MRI protocol and a combination of the Ab-MRI protocol and CE-CT for the detection of colorectal liver metastases.

METHODS

Study participants comprised 87 patients (51 males, 36 females; mean age, 67.2 ± 10.8 years) who had undergone gadoxetic acid-enhanced MRI and CE-CT during the initial work-up for colorectal cancer from 2010 to 2021. Each exam was independently reviewed by two readers in three reading sessions: (1) Only single-shot fast spin echo (FSE) T2-weighted or fat-suppressed-FSE-T2-weighted, diffusion-weighted, and hepatobiliary-phase images (Ab-MRI protocol 1 or 2); (2) all acquired MRI sequences (standard protocol); and (3) a combination of an Ab-MRI protocol (1 or 2) and CE-CT. Diagnostic performance was then statistically analyzed.

RESULTS

A total of 380 Lesions were analyzed, including 195 metastases (51.4%). Results from the two Ab-MRI protocols were similar. The sensitivity, specificity, and positive and negative predictive values from Ab-MRI were non-inferior to those from standard MRI (P > 0.05), while those from the combination of Ab-MRI protocol and CE-CT tended to be higher than those from Ab-MRI alone, although the difference was not significant (P > 0.05), and were quite similar to those from standard MRI (P > 0.05).

CONCLUSION

The diagnostic performances of two Ab-MRI protocols were non-inferior to that of the standard protocol. Combining Ab-MRI with CE-CT provided better diagnostic performance than Ab-MRI alone.

Liver Metastases: Correlation between Imaging Features and Pathomolecular Environments

A wide range of imaging manifestations of liver metastases can be encountered, as various primary cancers preferably metastasize to the liver (organ-specific metastases), with the imaging characteristics largely depending on various primary tumor-specific factors such as histopathologic category, degree of tumor differentiation, histologic behavior, and intratumor alterations. Characteristic imaging features potentially can help provide a more precise diagnosis in some clinical settings. These settings include those of (a) primary cancers of hollow organs such as gastrointestinal organs, the lungs, and the bladder, owing to the appearance of metastases that cannot be applied to the liver, which is a parenchymal organ; (b) unknown primary tumors; (c) more than one primary tumor; (d) another emergent malignancy; and (e) transformation to a different histopathologic tumor subtype. The characteristic features include the target sign on T2-weighted MR images or during the hepatobiliary phase of hypovascular metastasis, the peripheral rim washout sign on delayed phase images, peritumor hyperintensity during the hepatobiliary phase, hypervascular metastasis, a cystic appearance with marked hyperintensity on T2-weighted images, marked hyperintensity on T1-weighted images, calcification, capsular retraction, absence of the vessel-penetrating sign, distribution of liver metastases, and rare intraductal forms of metastases. In addition to various factors associated with the primary cancer, desmoplastic reactions around the tumor-which can be observed in adenocarcinomas with peripheral and peritumor enhancement, distinct arterioportal shunts with metastases from pancreatic ductal carcinoma, and pseudocirrhosis-also can affect these findings. The authors review the characteristic imaging findings of liver metastases from various primary cancers, with a focus on the mechanisms that underlie organ-specific liver metastases. Online supplemental material is available for this article. ^©RSNA, 2022.

Abbreviated Gadoxetic Acid-Enhanced MRI for the Detection of Liver Metastases in Patients With Potentially Resectable Pancreatic Ductal Adenocarcinoma

BACKGROUND

Gadoxetic acid-enhanced magnetic resonance imaging (MRI) is useful in detecting liver metastases from pancreatic ductal adenocarcinoma (PDAC). However, the long examination time limits its utility in the initial workup of patients with PDAC.

PURPOSE

To evaluate the incremental value of an abbreviated gadoxetic acid-enhanced MRI for the detection of liver metastases in patients with PDAC.

STUDY TYPE

Retrospective.

POPULATION

Patients (N = 130) with potentially resectable PDAC (women, 58 [44.6%]).

FIELD STRENGTH/SEQUENCE

1.5 T and 3 T; gradient dual-echo T1-weighted (in-phase and opposed-phase), fat-suppressed fast spin-echo T2-weighted, single-shot echo-planar diffusion-weighted, and three-dimensional fat-suppressed T1-weighted gradient-echo dynamic contrast-enhanced and hepatobiliary phase sequences, as well as contrast-enhanced computed tomography (CECT).

ASSESSMENT

Three radiologists independently reviewed three different image sets to detect liver metastases: set 1, CECT alone; set 2, CECT and abbreviated MRI comprising fat-suppressed T2-weighted, diffusion-weighted, and hepatobiliary phase images; and set 3, CECT and standard gadoxetic acid-enhanced MRI.

STATISTICAL TESTS

Figure of merit (FOM) was compared using the jackknife alternative free-response receiver operating characteristics, and other per-lesion and per-patient diagnostic parameters for each image set were compared using McNemar's and Fisher's test. P < 0.05 was considered statistically significant.

RESULTS

A total of 43 liver metastases were identified in 13 patients. Reader-averaged FOM to detect liver metastases were significantly higher for sets 2 (0.884) and 3 (0.886) than for set 1 (0.609), while they were comparable between sets 2 and 3 (P = 0.96). The mean per-patient sensitivities, negative predictive values, and accuracies were significantly higher for sets 2 and 3 than for set 1, while those between sets 2 and 3 were not significantly different (not applicable, P > 0.99, and P > 0.99, respectively).

DATA CONCLUSION

Gadoxetic acid-enhanced MRI combined with CECT had higher diagnostic performance than CECT alone for the detection of liver metastases in patients with PDAC. The incremental values were comparable for the abbreviated MRI and standard MRI.

LEVEL OF EVIDENCE

3 TECHNICAL EFFICACY: Stage 2.

Impact of baseline gadoxetic acid-enhanced liver magnetic resonance and diffusion-weighted imaging in resectable colorectal liver metastases: A prospective, monocentric study

BACKGROUND

Liver magnetic resonance imaging (MRI) utilizing hepatocyte-specific contrast agent and diffusion-weighted imaging (DWI) is currently used to properly stage colorectal liver metastases (CRLM) in patients candidate to liver surgery. However, the added value of liver MRI in choosing the treatment strategy in resectable CRLM over computed tomography (CT)-scan is not clear.

PATIENTS AND METHODS

This is a prospective monocentric collection of consecutive cases of patients with CRLM conceived with the aim to assess the added value of liver MRI in changing the initial treatment strategy planned according to CT-scan. Potential changes in the initially planned strategy were defined as: - from upfront surgery to perioperative chemotherapy (fluoropyrimidine and oxaliplatin) - from upfront surgery to first-line systemic therapy (doublet or triplet plus a biological agent) - from perioperative chemotherapy to first-line systemic therapy. Hypothesising that MRI may induce a change in the choice of the treatment strategy in the 20% of cases (alternative hypothesis), against a null hypothesis of 5%, with one-tailed alpha and beta errors of 0.05 and 0.20 respectively, 27 patients were needed. The added value of liver MRI would have been considered clinically meaningful if at least 4 changes in the treatment strategy were observed.

RESULTS

Among 27 enrolled patients, upfront surgery and perioperative chemotherapy strategies were chosen in 17 (63%) and 10 (37%) cases, respectively, based on CT-scan. After liver MRI, additional liver lesions were found in 8 patients (30%) and the initial strategy was changed in 7 patients (26%) (4 initially deemed candidate to upfront surgery and 3 initially sent to perioperative chemotherapy) that were treated with first-line systemic therapy.

CONCLUSIONS

Our results support the indication of the current guidelines on the routine use of liver MRI in the initial workup of patients with resectable CRLM with an MRI-driven changes of initial treatment plan in a relevant percentage of cases.

Molecular Imaging of Neuroendocrine Neoplasms

The key for molecular imaging is the use of a radiotracer with a radioactive and a functional component. While the functional component targets a specific feature of the tumor, the radioactive component makes the target visible. Neuroendocrine neoplasms (NEN) are a diverse group of rare tumors that arise from neuroendocrine cells found mainly in the gastroenteropancreatic system, lung, thyroid, and adrenal glands. They are characterized by the expression of specific hormone receptors on the tumor cell surface, which makes them ideal targets for radiolabeled peptides. The most commonly expressed hormone receptors on NEN cells are the somatostatin receptors. They can be targeted for molecular imaging with various radiolabeled somatostatin analogs, but also with somatostatin antagonists, which have shown improved imaging quality. 18F-DOPA imaging has become a second-line imaging modality in NENs, with the exception of the evaluation of advanced medullary thyroid carcinoma. Alternatives for NENs with insufficient somatostatin receptor expression due to poor differentiation involve targeting glucose metabolism, which can also be used for prognosis. For the localization of the often-small insulinoma, glucagon-like peptide-1 (GLP-1) receptor imaging has become the new standard. Other alternatives involve metaiodobenzylguanidine and the molecular target C-X-C motif chemokine receptor-4. In addition, new radiopeptides targeting the fibroblast activation protein, the glucose-dependent insulinotropic polypeptide receptor and cholecystokinin-2 receptors have been identified in NENs and await further evaluation. This mini-review aims to provide an overview of the major molecular imaging modalities currently used in the field of NENs, and also to provide an outlook on future developments.

The management of colorectal liver metastases amenable of surgical resection: How to shape treatment strategies according to clinical, radiological, pathological and molecular features

Metastatic colorectal cancer (mCRC) patients have poor chances of long term survival, being < 15% of them still alive after 5 years from diagnosis. Nonetheless, patients with colorectal liver metastases (CRLM) may be eligible for metastases resection thus being able to achieve long-term disease remission and survival. The likelihood for patients with CRLM of being or becoming eligible for liver metastasectomy is increasing, thanks to the evolution of surgical techniques, the availability of active systemic treatments and the widespread diffusion of experienced multidisciplinary boards to manage these patients. However, disease relapse after liver surgery is common and occurs in two-thirds of resected patients. Therefore, adequate radiological staging and risk stratification is crucial for the optimal selection of patients candidate to surgery in order to maximize the benefit-risk ratio of liver metastasectomy and to individualize the treatment strategy. Based on the multidimensional assessment, three possible approaches are available: upfront liver surgery followed by adjuvant chemotherapy, perioperative chemotherapy preceding and following liver surgery, and an upfront systemic treatment including chemotherapy plus a targeted agent, both chosen according to patients' and tumours' characteristics, then followed by liver surgery if indicated. In this review, we describe the most important factors impacting the therapeutic choices in patients with resectable and potentially resectable CRLM, and we discuss the most promising factors that may reshape the future decision-making process of these patients.

Improved sensitivity and positive predictive value of contrast-enhanced intraoperative ultrasound in colorectal cancer liver metastasis: a systematic review and meta-analysis

BACKGROUND

Surgery is an effective treatment for improving the survival rate of patients with colorectal cancer liver metastases (CRLM). However, accurately determining the resection margin of liver lesions during surgery remains challenging. Therefore, this study aimed to evaluate the sensitivity and predictive value of intraoperative contrast-enhanced ultrasound (CE-IOUS) in CRLM patients undergoing surgery.

METHODS

We performed a literature search of the PubMed, Cochrane Central Register of Controlled Trials, Embase, Web of Science, China National Knowledge Infrastructure (CNKI), Wanfang, and Weipu databases using the following search terms: metastatic liver cancer, colorectal cancer, sensitivity, contrast-enhanced intraoperative ultrasound, CE-IOUS, colorectal liver metastases, and CRLM. The search period was set from the date of establishment of the database to September 2021. Quality assessment of diagnostic accuracy studies 2 (QUADAS-2) recommended by the Cochrane Collaboration was used to assess the methodological quality of the included studies, and network meta-analysis was performed using Stata 15.0 software.

RESULTS

A total of 10 articles met the inclusion criteria. The meta-analysis results showed that the overall sensitivity and specificity of CE-IOUS were 0.96 [95% confidence interval (CI), 0.95-0.97] and 0.75 (95% CI, 0.70-0.80), respectively. The overall sensitivity and specificity of IOUS were 0.84 (95% CI, 0.82-0.86) and 0.82 (95% CI, 0.77-0.87), respectively. The area under the summary receiving operating characteristic (SROC) curves (AUCs) of CE-IOUS and IOUS were 0.9753 and 0.8590, respectively. The odds ratio (OR) and 95% CI of CE-IOUS changed the surgical margin were 0.205 and 0.071-0.465, P=0.000, the difference was statistically significant.

DISCUSSION

Based on the results of this meta-analysis, CE-IOUS improved the sensitivity and predictive value of CRLM detection compared with IOUS, and is more suitable for intraoperative planning of surgical margins. At present, it is the most sensitive imaging method available, and is recommended for use during liver resection to provide doctors with more reliable information during surgery.

Characteristics of false-positive lesions in evaluating colorectal liver metastases on gadoxetic acid-enhanced magnetic resonance imaging

PURPOSE

Gadoxetic acid-enhanced MRI (Gd-EOB-MRI) shows higher sensitivity for colorectal liver metastases (CRLM) than contrast-enhanced computed tomography (CECT). However, the details of false-positive lesions for each imaging modality are unknown.

METHODS

Cases undergoing hepatectomy for CRLM following a preoperative evaluation with both CECT and Gd-EOB-MRI between July 2008 and December 2016 were reviewed. The false-positive and false-negative rates were assessed for each modality, and the characteristics of false-positive lesions were evaluated.

RESULTS

We evaluated 275 partial hepatectomies in 242 patients without preoperative chemotherapy. Among the 275 hepatectomies, 546 lesions were recognized by CECT and/or Gd-EOB-MRI. The false-positive rates for CECT and Gd-EOB-MRI were 4% (18/422) and 7% (37/536), respectively. The size of false-positive lesions was significantly smaller than that of correctly diagnosed lesions (median: 28 mm [3-120 mm] vs 7.6 mm [320 mm], P  < 0.001). Compared with the 233 correctly diagnosed lesions ≤ 20 mm in diameter, false-positive lesions were more frequently located near the liver surface or vasculobiliary structures than true lesions (33/37 [89%] vs 149/233 [64%], respectively; P  = 0.0021).

CONCLUSION

Gd-EOB-MRI had a 7% false-positive rate. A small size and tumor location near the surface or near vasculobiliary structures were associated with false positivity.

Differentiation of histopathological growth patterns of colorectal liver metastases by MRI features

Background

It is necessary to develop an accurate non-invasive method to determine the histopathological growth pattern (HGP) of colorectal liver metastasis (CRLM) before surgery. The present study aimed to identify various HGPs of CRLM by magnetic resonance imaging (MRI) features.

Methods

This retrospective study included 53 chemo-naïve patients with CRLM between December 2013 and September 2019. The HGPs of CRLM were assessed according to the international consensus guidelines, and were classified as either replacement HGP (rHGP) or non-rHGP. The MRI features of CRLM were retrospectively reviewed in consensus by two radiologists. The differences of MRI features between rHGP and non-rHGP tumors were compared by using Chi-square test and Student's t-test. The Spearman or Pearson correlation analysis was performed to determine the correlation between different MRI features. A receiver operating characteristic (ROC) curve was plotted to evaluate the diagnostic ability.

Results

Of the 53 chemo-naïve patients (mean age, 60.11±9.85 years; age range, 38-86 years), 12 were diagnosed as rHGP, while 41 were diagnosed as non-rHGP. Rim enhancement were more common in rHGP than in non-rHGP (P<0.001). Besides, the diameter difference (ΔD) between the precontrast and postcontrast images of rHGP was significantly larger than that of the non-rHGP (P=0.001). The rim width was correlated with ΔD, but not correlated with tumor size. The non-rHGP colorectal liver metastases were prone to be washed out in the delayed phases (P=0.043). The area under the curve (AUC) for the differentiation of rHGP and non-rHGP by using rim enhancement and ΔD was 0.828 (95% CI: 0.708-0.949).

Conclusions

The MRI features of CRLM are characteristic and could help to differentiate rHGP and non-rHGP.

Current Landscape and Future Perspectives of Abbreviated MRI for Hepatocellular Carcinoma Surveillance

While ultrasound (US) is considered an important tool for hepatocellular carcinoma (HCC) surveillance, it has limited sensitivity for detecting early-stage HCC. Abbreviated MRI (AMRI) has recently gained popularity owing to better sensitivity in its detection of early-stage HCC than US, while also minimizing the time and cost in comparison to complete contrast-enhanced MRI, as AMRI includes only a few essential sequences tailored for detecting HCC. Currently, three AMRI protocols exist, namely gadoxetic acid-enhanced hepatobiliary-phase AMRI, dynamic contrast-enhanced AMRI, and non-enhanced AMRI. In this study, we discussed the rationale and technical details of AMRI techniques for achieving optimal surveillance performance. The strengths, weaknesses, and current issues of each AMRI protocol were also elucidated. Moreover, we scrutinized previously performed AMRI studies regarding clinical and technical factors. Reporting and recall strategies were discussed while considering the differences in AMRI protocols. A risk-stratified approach for the target population should be taken to maximize the benefits of AMRI and the cost-effectiveness should be considered. In the era of multiple HCC surveillance tools, patients need to be fully informed about their choices for better adherence to a surveillance program.

Role of CT in Two-Stage Liver Surgery

Complete resection is the only potentially curative treatment for primary or metastatic liver tumors. Improvements in surgical techniques such as conventional two-stage hepatectomy (TSH) with portal vein embolization and ALPPS (associating liver partition and portal vein ligation for staged hepatectomy) promote hypertrophy of the future liver remnant (FLR), expanding resection criteria to include patients with widespread hepatic disease who were formerly not considered candidates for resection. Radiologists are essential in the multidisciplinary approach required for TSH. In particular, multidetector CT has a critical role throughout the various stages of this surgical process. The aims of CT before the first stage of TSH are to define the feasibility of surgery, assess the number and location of liver tumors in relation to relevant anatomy, and provide a detailed anatomic evaluation, including vascular and biliary variants. Volume calculation with CT is also essential to determine if the FLR is sufficient to avoid posthepatectomy liver failure. The objectives of CT between the first and second stages of TSH are to recalculate liver volumes (ie, assess FLR hypertrophy) and depict expected liver changes and complications that could modify the surgical plan or preclude the second stage of definitive resection. In this review, the importance of CT throughout different stages of TSH is discussed and key observations that contribute to surgical planning are highlighted. In addition, the advantages and limitations of MRI for detection of liver metastases and assessment of complications are briefly described. ^©RSNA, 2022.

Imaging evaluation of the liver in oncology patients: A comparison of techniques

The liver is commonly affected by metastatic disease. Therefore, it is essential to detect and characterize liver metastases, assuming that patient management and prognosis rely on it. The imaging techniques that allow non-invasive assessment of liver metastases include ultrasonography, computed tomography (CT), magnetic resonance imaging (MRI), positron emission tomography (PET)/CT, and PET/MRI. In this paper, we review the imaging findings of liver metastases, focusing on each imaging modality's advantages and potential limitations. We also assess the importance of different imaging modalities for the management, follow-up, and therapy response of liver metastases. To date, both CT and MRI are the most appropriate imaging methods for initial lesion detection, follow-up, and assessment of treatment response. Multiparametric MRI is frequently used as a problem-solving technique for liver lesions and has evolved substantially over the past decade, including hardware and software developments and specific intravenous contrast agents. Several studies have shown that MRI performs better in small-sized metastases and moderate to severe liver steatosis cases. Although state-of-the-art MRI shows a greater sensitivity for detecting and characterizing liver metastases, CT remains the chosen method. We also present the controversial subject of the "economic implication" to use CT over MRI.

New Directions in Imaging Neuroendocrine Neoplasms

Purpose of Review

Accurate imaging is crucial for correct diagnosis, staging, and therapy of neuroendocrine neoplasms (NENs). The search for the optimal imaging technique has triggered rapid development in the field. This review aims at giving an overview on contemporary imaging methods and providing an outlook on current progresses.

Recent Findings

The discovery of molecular targets due to the overexpression of specific peptide hormone receptors on the NEN’s surface has triggered the development of multiple radionuclide imaging modalities. In addition to the established imaging technique of targeting somatostatin receptors, several alternative radioligands have been developed. Targeting the glucagon-like peptide-1 receptor by exendin-4 has a high sensitivity in localizing insulinomas. For dedifferentiated NENs, new molecular targets such as the C-X-C motif chemokine-receptor-4 have been evaluated. Other new targets involve the fibroblast activation protein and the cholecystokinin-2 receptors, where the ligand minigastrin opens new possibilities for the management of medullary thyroid carcinoma.

Summary

Molecular imaging is an emerging field that improves the management of NENs.

Evaluation of the Diagnostic Performance of Positron Emission Tomography/Magnetic Resonance for the Diagnosis of Liver Metastases

OBJECTIVE

The aim of this study was to compare the performance of positron emission tomography (PET)/magnetic resonance (MR) versus stand-alone PET and stand-alone magnetic resonance imaging (MRI) in the detection and characterization of suspected liver metastases.

MATERIALS AND METHODS

This multi-institutional retrospective performance study was approved by the institutional review boards and was Health Insurance Portability and Accountability Act compliant, with waiver of informed consent. Seventy-nine patients with confirmed solid extrahepatic malignancies who underwent upper abdominal PET/MR between February 2017 and June 2018 were included. Where focal hepatic lesions were identified, the likelihood of a diagnosis of a liver metastasis was defined on an ordinal scale for MRI, PET, and PET/MRI by 3 readers: 1 nuclear medicine physician and 2 radiologists. The number of lesions per patient, lesion size, and involved hepatic segments were recorded. Proof of metastases was based on histopathologic correlation or clinical/imaging follow-up. Diagnostic performance was assessed using sensitivity, specificity, positive and negative predictive values, and receiver operator characteristic curve analysis.

RESULTS

A total of 79 patients (53 years, interquartile range, 50-68; 43 men) were included. PET/MR had a sensitivity of 95%, specificity of 97%, positive predictive value of 97%, and negative predictive value of 95%. The sensitivity, specificity, positive predictive value, and negative predictive value of MRI were 88%, 98%, 98%, and 90% and for PET were 83%, 97%, 97%, and 86%, respectively. The areas under the curve for PET/MRI, MRI, and PET were 95%, 92%, and 92%, respectively.

CONCLUSIONS

Contrast-enhanced PET/MR has a higher sensitivity and negative predictive value than either PET or MRI alone in the setting of suspected liver metastases. Fewer lesions were characterized as indeterminate by PET/MR in comparison with PET and MRI. This superior performance could potentially impact treatment and management decisions for patients with suspected liver metastases.

Dual contrast liver MRI: a pictorial illustration

Liver magnetic resonance imaging (MRI) is a commonly performed imaging technique with multiple indications and applications. There are two general groups of contrast agents used when imaging the liver, extracellular contrast agents (ECA) and hepatobiliary agents (HBA), each of which has its own advantages and limitations. Liver MRI with ECA provides excellent information on abdominal vasculature and better quality multi-phasic studies for characterization of focal liver lesions. HBA improves lesion detection, provides information regarding liver function and can be helpful for evaluating biliary tree anatomy, excretion, anastomotic stenoses, or leaks. Most liver MRI studies are usually performed with one agent, however in some cases, a second study is performed with another agent to obtain additional information or confirm the findings in the first study. Administering both agents in a single exam can potentially eliminate the need for additional imaging in certain situations. In this pictorial review, the techniques and indications for dual contrast MRI will be detailed with multiple demonstrative examples.

Newly detected liver nodules with a history of colorectal cancer: are they metastatic? Review of 2,632 cases in a single center

Background

The diagnosis of newly detected liver nodules in patients with colorectal cancer (CRC) is crucial for determining prognosis and treatment. Accurate identification of benign nodules can help avoid unnecessary therapy. The aim of our study was to retrospectively review patients with CRC who underwent liver resection for benign liver nodules misdiagnosed as CRC metastasis (CRLM) in our institution.

Methods

We reviewed all patients with a history of CRC who underwent liver resection from January 2012 to December 2019 in our institution. We specifically focused on nodules pathologically confirmed as benign. The pathology was rechecked by an independent pathologist. The clinicopathological characteristics of these patients were collected. Preoperative imaging examinations, including ultrasound (US), magnetic resonance imaging (MRI), and positron emission tomography-computed tomography (PET-CT) were reviewed.

Results

From 2012 to 2019, a total of 2,632 patients with CRC who were preoperatively diagnosed CRLM received liver resection, among which 2,584 (98.2%) cases were proven to be malignant, and 48 (1.8%) cases were benign. Among these 48 cases, 24 were pathologically confirmed as focal nodular hyperplasia (FNH), 9 were peliosis, 10 were inflammatory lesions, and 5 were hemangioma. At least one preoperative imaging examination indicated CRLM, with a median size of 2.0 cm (range, 0.4–8.0 cm). Before liver resection, ten patients received chemotherapy after the discovery of liver nodules.

Conclusions

It should be noted that newly detected liver nodules in patients with a history of CRC could be benign. Accurate diagnosis of liver nodules in CRC is necessary to avoid overtreatment and to identify cost-effective medication.

Risk of nephrogenic systemic fibrosis in patients with impaired renal function undergoing fixed-dose gadoxetic acid-enhanced magnetic resonance imaging

PURPOSE

To assess the risk of nephrogenic systemic fibrosis (NSF) in patients with renal impairment undergoing gadoxetic acid-enhanced magnetic resonance imaging.

METHODS

This retrospective study included patients who had an estimated glomerular filtration rate (eGFR) below 60 mL/min per 1.73 m² or had undergone dialysis around the time of gadoxetic acid exposure from January 2010 to November 2019. All patients received at least one intravenous injection of gadoxetic acid at a fixed dose of 2.5 mmol. The primary endpoint was the development of NSF after exposure to gadoxetic acid based on Girardi's clinicopathological scoring system.

RESULTS

A total of 204 patients with renal impairment received 424 injections of gadoxetic acid, of which 131 and 54 had an eGFR of 30-59 and < 30 mL/min per 1.73 m², respectively, and 19 had undergone hemodialysis. Eighty-two patients received multiple injections, with 23 receiving five or more injections. The dose of each exposure ranged from 0.02 to 0.07 mmol/kg and the cumulative doses ranged from 0.02 to 0.45 mmol/kg. Thirty-three patients had concomitant Child-Pugh class B or C cirrhosis. No NSF was detected during follow-up (median 20 months; range 6 days to 111 months). The upper bound of the 95% confidence interval for NSF risk was 2.2% and 1.1% per patient and examination, respectively.

CONCLUSION

No NSF was detected in this study. However, it is premature to ascertain the risk of NSF using gadoxetic acid in patients with renal impairment and further studies are warranted.

Can preoperative liver MRI with gadoxetic acid help reduce open-close laparotomies for curative intent pancreatic cancer surgery?

Objectives

To evaluate gadoxetic acid-enhanced liver MRI (EOB-MRI) versus contrast-enhanced computed tomography (CECT) for preoperative detection of liver metastasis (LM) and reduction of open-close laparotomies for pancreatic ductal adenocarcinoma (PDAC).

Methods

Sixty-six patients with PDAC had undergone preoperative EOB-MRI and CECT. LM detection by EOB-MRI and CECT and their impact on surgical planning, open-close laparotomies were compared by clinical and radiology reports and retrospective analysis of imaging by two blinded independent readers. Histopathology or imaging follow-up was the reference standard. Statistical analysis was performed at patient and lesion levels with two-sided McNemar tests.

Results

EOB-MRI showed higher sensitivity versus CECT (71.7% [62.1-80.0] vs. 34% [25.0-43.8]; p = 0.009), comparable specificity (98.6%, [96.9-99.5] vs. 100%, [99.1-100], and higher AUROC (85.1%, [80.4-89.9] vs. 66.9%, [60.9-73.1]) for LM detection. An incremental 7.6% of patients were excluded from surgery with a potential reduction of up to 13.6% in futile open-close laparotomies due to LM detected on EOB-MRI only.

Conclusions

Preoperative EOB-MRI has superior diagnostic performance in detecting LM from PDAC. This better informs surgical eligibility with potential reduction of futile open-close laparotomies from attempted curative intent pancreatic cancer surgery.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40644-021-00416-4.

Endoscopic Ultrasound for Detection of Liver Metastasis: Hope or Hype?

Transabdominal ultrasonography, contrast-enhanced computed tomography, and magnetic resonance imaging (MRI) are the common diagnostic tests for the detection of hepatic lesions. Use of enhanced and advanced MRI technique, that is, diffusion weighted MRI and hepatocyte-specific contrast agents, has further improved the accuracy of detection of metastatic liver lesions ≤10 mm in diameter. However, even with these advanced imaging modalities sensitivity is low for lesions smaller than 10 mm when compared with standard intraoperative ultrasound. Endoscopic ultrasound (EUS) is an emerging imaging modality with resolution sufficient to detect and sample lesions as small as 5 mm in diameter. In this news and views, we have discussed the role of standard and enhanced EUS for the detection of metastatic liver lesions.

Diffusion-Weighted Imaging: An Exciting and Problem-Solving Tool in Patients with Hepatic Metastases

Background  The diffusion-weighted imaging (DWI) is based on the random Brownian motion of water molecules that influences image contrast depending on different pathological conditions.

Objective  The purpose of this study was to evaluate the efficacy of various magnetic resonance imaging (MRI) sequences including diffusion-weighted and gadobenate-enhanced MRI in the detection and characterization of liver lesions in a patient of known primary malignancy and to compare MRI with contrast-enhanced computed tomography (CECT) and ultrasonography (USG) in the detection of liver metastases.

Methods  All patients underwent a multiphase MRI. The final diagnosis was established by histopathological examination.

Results  A total of 43 patients of known primary malignancy were enrolled. MRI gave a provisional diagnosis of liver metastases in 21 patients and benign disease in 22 patients with histopathological correlation revealing two false-negative and one false-positive result. In the detection of lesions, DWI outscored other sequences (92.9 vs. 83.5% in hepatobiliary phase vs. 55.0% in T ₂ -weighted sequences) with a statistically significant difference noted only in comparison with T ₂ -weighted sequences ( p < 0.001). In 16 patients, MRI added new lesions that were not detected by CECT/USG. The sensitivity and specificity of MRI for detecting metastases were 90.9%/95.2% and 97.9%/96.8% for per-patient and per-lesion basis, respectively.

Conclusion  Multiphase MRI improved both the detection and characterization of liver metastases. Adding DWI to the routine MR sequences helped in detecting small liver metastases (<10 mm) not detected by other sequences.

Radiomics analysis of contrast-enhanced CT for classification of hepatic focal lesions in colorectal cancer patients: its limitations compared to radiologists

OBJECTIVE

To evaluate diagnostic performance of a radiomics model for classifying hepatic cyst, hemangioma, and metastasis in patients with colorectal cancer (CRC) from portal-phase abdominopelvic CT images.

METHODS

This retrospective study included 502 CRC patients who underwent contrast-enhanced CT and contrast-enhanced liver MRI between January 2005 and December 2010. Portal-phase CT images of training (n = 386) and validation (n = 116) cohorts were used to develop a radiomics model for differentiating three classes of liver lesions. Among multiple handcrafted features, the feature selection was performed using ReliefF method, and random forest classifiers were used to train the selected features. Diagnostic performance of the developed model was compared with that of four radiologists. A subgroup analysis was conducted based on lesion size.

RESULTS

The radiomics model demonstrated significantly lower overall and hemangioma- and metastasis-specific polytomous discrimination index (PDI) (overall, 0.8037; hemangioma-specific, 0.6653; metastasis-specific, 0.8027) than the radiologists (overall, 0.9622-0.9680; hemangioma-specific, 0.9452-0.9630; metastasis-specific, 0.9511-0.9869). For subgroup analysis, the PDI of the radiomics model was different according to the lesion size (< 10 mm, 0.6486; ≥ 10 mm, 0.8264) while that of the radiologists was relatively maintained. For classifying metastasis from benign lesions, the radiomics model showed excellent diagnostic performance, with an accuracy of 84.36% and an AUC of 0.9426.

CONCLUSION

Albeit inferior to the radiologists, the radiomics model achieved substantial diagnostic performance when differentiating hepatic lesions from portal-phase CT images of CRC patients. This model was limited particularly to classifying hemangiomas and subcentimeter lesions.

KEY POINTS

• Albeit inferior to the radiologists, the radiomics model could differentiate cyst, hemangioma, and metastasis with substantial diagnostic performance using portal-phase CT images of colorectal cancer patients. • The radiomics model demonstrated limitations especially in classifying hemangiomas and subcentimeter liver lesions.

Dedicated MRI staging versus surgical staging of peritoneal metastases in colorectal cancer patients considered for CRS-HIPEC; the DISCO randomized multicenter trial

Background

Selecting patients with peritoneal metastases from colorectal cancer (CRCPM) who might benefit from cytoreductive surgery followed by hyperthermic intraperitoneal chemotherapy (CRS-HIPEC) is challenging. Computed tomography generally underestimates the peritoneal tumor load. Diagnostic laparoscopy is often used to determine whether patients are amenable for surgery. Magnetic resonance imaging (MRI) has shown to be accurate in predicting completeness of CRS. The aim of this study is to determine whether MRI can effectively reduce the need for surgical staging.

Methods

The study is designed as a multicenter randomized controlled trial (RCT) of colorectal cancer patients who are deemed eligible for CRS-HIPEC after conventional CT staging. Patients are randomly assigned to either MRI based staging (arm A) or to standard surgical staging with or without laparoscopy (arm B). In arm A, MRI assessment will determine whether patients are eligible for CRS-HIPEC. In borderline cases, an additional diagnostic laparoscopy is advised. The primary outcome is the number of unnecessary surgical procedures in both arms defined as: all surgeries in patients with definitely inoperable disease (PCI > 24) or explorative surgeries in patients with limited disease (PCI < 15). Secondary outcomes include correlations between surgical findings and MRI findings, cost-effectiveness, and quality of life (QOL) analysis.

Conclusion

This randomized trial determines whether MRI can effectively replace surgical staging in patients with CRCPM considered for CRS-HIPEC.

Trial registration

Registered in the clinical trials registry of U.S. National Library of Medicine under NCT04231175.

Imaging of colorectal cancer liver metastases using contrast-enhanced US, multidetector CT, MRI, and FDG PET/CT: a meta-analysis

BACKGROUND

Imaging of colorectal cancer liver metastases (CRCLMs) has improved in recent years. Therefore, the role of current imaging techniques needs to be defined.

PURPOSE

To assess the diagnostic performance of contrast-enhanced ultrasound (CEUS), multidetector computed tomography (MDCT), magnetic resonance imaging (MRI), and fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT in the detection of CRCLMs.

MATERIAL AND METHODS

PubMed database was searched for articles published during 2000-2019. Inclusion criteria were as follows: diagnosis/suspicion of CRCLMs; CEUS, MDCT, MRI, or FDG PET/CT performed for the detection of CRCLMs; prospective study design; histopathologic examination, intraoperative findings and/or follow-up used as reference standard; and data for calculating sensitivity and specificity reported.

RESULTS

Twelve prospective studies were assessed, including 536 patients with CRCLMs (n = 1335). On a per-lesion basis, the sensitivity of CEUS, MDCT, MRI, and FDG PET/CT was 86%, 84%, 89%, and 62%, respectively. MRI had the highest sensitivity on a per-lesion analysis. CEUS and MDCT had comparable sensitivities. On a per-patient basis, the sensitivity and specificity of CEUS, MDCT, MRI, and FDG PET/CT was 80% and 97%, 87% and 95%, 87% and 94%, and 96% and 97%, respectively. The per-patient sensitivities for MRI and MDCT were similar. The sensitivity for MRI was higher than that for CEUS, MDCT, and FDG PET/CT for lesions <10 mm and lesions at least 10 mm in size. Hepatospecific contrast agent did not improve diagnostic performances.

CONCLUSION

MRI is the preferred imaging modality for evaluating CRCLMs. Both MDCT and CEUS can be used as alternatives.

Clinical Performance of Abbreviated Liver MRI for the Follow-Up of Patients With Colorectal Liver Metastases

OBJECTIVE. The objective of our study was to compare an abbreviated liver MRI protocol with a standard liver MRI protocol for the posttreatment follow-up of colorectal metastases in assessing disease presence, segmental involvement, and response to chemotherapy and for surgical planning. MATERIALS AND METHODS. This retrospective single-center study reviewed consecutive chemotherapy-naïve patients with colorectal liver metastases (April 1, 2011-August 31, 2017) who underwent gadoxetate disodium-enhanced MRI on a 1.5-T unit before and 8-12 weeks after chemotherapy. Two radiologists blinded to outcomes independently reviewed images obtained using standard MRI sequences at baseline and after treatment. The standard MRI sequences were the following: axial T1-weighted, axial T2-weighted, axial DWI (b values = 0-750 s/mm²), axial multiphase contrast-enhanced T1-weighted, and axial and coronal hepatobiliary phase (HBP) T1-weighted sequences. The standard sequences obtained at baseline and the abbreviated protocol sequences (i.e., HBP gadoxetate disodium-enhanced T1-weighted and DWI sequences) obtained after treatment were reviewed. For each image set, reviewers assessed disease presence and segmental involvement; in addition, for images obtained after therapy, treatment response according to RECIST 1.1 was recorded. RESULTS. One hundred thirteen patients (73 men and 40 women; mean age, 61.6 years) were evaluated. The total number of metastases showed high agreement between the standard protocol and abbreviated protocol (intraclass correlation coefficient = 0.97). There was good agreement between the protocols for segmental involvement (weighted κ = 0.73-0.85), and the weighted kappa was 0.82 for all segments. Discrepancies in segmental involvement did not alter potential surgical planning. Categorization of RECIST 1.1 treatment response using the abbreviated protocol versus the standard protocol showed excellent agreement (weighted κ = 0.92). CONCLUSION. An abbreviated liver MRI protocol (i.e., HBP gadoxetate disodium-enhanced T1-weighted and DWI sequences) allows assessment after chemotherapy similar to a standard liver MRI protocol. Use of the abbreviated protocol can reduce imaging time without sacrificing diagnostic performance for the follow-up of colorectal liver metastases.

The diagnostic performance of a simulated "short" gadoxetic acid-enhanced MRI protocol is similar to that of a conventional protocol for the detection of colorectal liver metastases

OBJECTIVES

To compare the performance of standard and simulated short gadoxetic acid-enhanced MRI protocols for the detection of colorectal liver metastases (CRLM).

METHODS

From 2008 to 2017, 67 patients (44 men (66%); mean age 65 ± 11 years old) who underwent gadoxetic acid-enhanced MRI during the initial work-up for colorectal cancer were included. Exams were independently reviewed by two readers blinded to clinical data in two reading sessions: (1) all acquired sequences (standard "long" protocol) and (2) only T2-weighted, diffusion-weighted, and hepatobiliary phase images (simulated "short" protocol). Readers characterized detected lesions using a 5-point scale (1-certainly benign to 5-certainly malignant). A lesion was considered a CRLM when the score was ≥ 3. The reference standard was histopathology or 12-month imaging follow-up. Chi-square, Student's t, and McNemar tests were used for comparisons.

RESULTS

A total of 486 lesions including 331 metastases (68%) were analyzed. The metastasis detection rate was 86.1% (95% CI 82-89.4)-86.7% (82.6-90) and 85.8% (81.6-89.2)-87% (82.9-90.2) with the short and long protocols, respectively (p > 0.99). Among detected lesions, 92.1% (89.1-94.4)-94.8% (92.2-96.6) and 84.6% (80.8-87.7)-88.8% (85.4-91.5) were correctly classified with the short and long protocols, respectively (p = 0.13 and p = 0.10). The results remained unchanged when lesions scored ≥ 4 were considered as CRLM.

CONCLUSION

The diagnostic performance of a simulated short gadoxetic enhanced-MR protocol including T2-weighted, diffusion-weighted, and hepatobiliary phase appears similar to that of a standard long protocol including dynamic phase images. Since this protocol shortens the duration of MR examination, it could facilitate the evaluation of patients with colorectal liver metastases.

KEY POINTS

• The detection rate of colorectal metastases with a simulated, short, MRI protocol was similar to that of a standard protocol. • The performance of both protocols for the differentiation of metastases and benign lesions appears to be similar. • A short MR imaging protocol could facilitate the evaluation of patients with colorectal liver metastases.

Diagnostic accuracy of contrast-enhanced diffusion-weighted MRI for liver metastases of pancreatic cancer: towards adequate staging and follow-up of pancreatic cancer - DIA-PANC study: study protocol for an international, multicenter, diagnostic trial

BACKGROUND

At the time of surgery, approximately 10-20% of the patients with pancreatic cancer are considered unresectable because of unexpected liver metastasis, peritoneal carcinomatosis or locally advanced disease. This leads to futile surgical treatment with all the associated morbidity, mortality and costs. More than 50% of all liver metastases develop in the first six months postoperatively. These (subcentimeter) liver metastases are most likely already present at the time of diagnosis and have not been identified pre-operatively, due to the poor sensitivity of routine preoperative contrast-enhanced CT (CECT).

METHODS

The DIA-PANC study is a prospective, international, multicenter, diagnostic cohort study investigating diffusion-weighted, contrast-enhanced MRI for the detection of liver metastases in patients with all stages of pancreatic cancer. Indeterminate or malignant liver lesions on MRI will be further investigated histopathologically. For patients with suspected liver lesions without histopathological proof, follow up imaging with paired CT and MRI at 3-, 6- and 12-months will serve as an alternative reference standard.

DISCUSSION

The DIA-PANC trial is expected to report high-level evidence of the diagnostic accuracy of MRI for the detection of liver metastases, resulting in significant value for clinical decision making, guideline development and improved stratification for treatment strategies and future trials. Furthermore, DIA-PANC will contribute to our knowledge of liver metastases regarding incidence, imaging characteristics, their number and extent, and their change in time with or without treatment. It will enhance the worldwide implementation of MRI and consequently improve personalized treatment of patients with suspected pancreatic ductal adenocarcinoma.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT03469726 . Registered on March 19th 2018 - Retrospectively registered.

Anatomic and Functional Imaging of Neuroendocrine Tumors

OPINION STATEMENT

Neuroendocrine tumors (NETs) can occur in a wide variety of organs and display a spectrum of pathologic behavior. Accurate and effective imaging is paramount to the diagnosis, staging, therapy, and surveillance of patients with NET. There have been continuous advancements in the imaging of NET which includes anatomic and functional techniques.

Neoadjuvant chemotherapy followed by curative-intent surgery for perihilar cholangiocarcinoma based on its anatomical resectability classification and lymph node status

BACKGROUND

The prognosis of patients with perihilar cholangiocarcinoma have been unsatisfactory. We established new anatomical resectability classification for patients with localized perihilar cholangiocarcinoma and performed neoadjuvant chemotherapy followed by curative-intent surgery based on its resectability classification and lymph node status to improve prognosis. This study aimed to clarify the long-term outcomes and validation of our strategy.

METHODS

Between September 2010 and August 2018, 72 consecutive patients with perihilar cholangiocarcinoma were classified into three groups: Resectable (R = 29), Borderline resectable (BR = 23), and Locally advanced (LA = 20), based on the two factors of tumor vascular and biliary extension. R with clinically lymph node metastasis, BR, and LA patients received neoadjuvant chemotherapy using gemcitabine plus S-1.

RESULTS

Forty-seven patients (65.3%) received neoadjuvant chemotherapy: R in 8, BR in 21, and 18 in LA, respectively. Fifty-nine patients (68.1%) underwent curative-intent surgery: R in 26, BR in 17, and LA in 6. Five-year disease-specific survival was 31.5% (median survival time: 33.0 months): 50.3% (not reached) in R, 30.0% (31.4 months) in BR, and 16.5% (22.5 months) in LA, which were relatively stratified. Among 49 patients with resection, disease-specific survival was 43.8% (57.0 months): 57.6% (not reached) in R, 41.0% (52.4 months) in BR, and 0% (49.4 months) in LA, which were significantly good prognosis compared to 23 patients without resection (17.2 months). Multivariate analysis identified preoperative high carcinoembryonic antigen levels (more than 8.5 ng/ml) and pT4 as independent poor prognostic factor of patients with resection.

CONCLUSION

Neoadjuvant chemotherapy based on resectability classification and lymph node status was feasible, and was considered efficacious in selected patients.

Additional value of gadoxetic acid-enhanced MRI to conventional extracellular gadolinium-enhanced MRI for the surgical management of colorectal and neuroendocrine liver metastases

BACKGROUND

Liver resection being the only potentially curative treatment for patients with liver metastasis, it is critical to select the appropriate preoperative imaging modality. The aim of this study was to assess the impact of preoperative gadoxetic acid-enhanced MRI compared to a conventional extracellular gadolinium-enhanced MRI on the surgical management of colorectal and neuroendocrine liver metastasis.

METHODS

We included 110 patients who underwent both a gadoxetic acid-enhanced MRI (hepatospecific contrast) and conventional extracellular gadolinium for the evaluation of colorectal or neuroendocrine liver metastases, from January 2012 to December 2015 at the CHU de Québec - Université Laval. When the number of lesions differed, a hepatobiliary surgeon evaluated if the gadoxetic acid-enhanced MRI modified the surgical management.

RESULTS

Gadoxetic acid-enhanced MRI found new lesions in 25 patients (22.7%), excluded lesions in 18 patients (16.4%) and identified the same number in 67 patients (60.9%). The addition of the gadoxetic acid-enhanced MRI directly altered the surgical management in 19 patients overall (17.3% (95% CI [10.73-25.65])).

CONCLUSION

Despite the additional cost associated with gadoxetic acid-enhanced MRI compared to conventional extracellular gadolinium-enhanced MRI, the use of this contrast agent has a significant impact on the surgical management of patients with liver metastases.

Preoperative detection of colorectal liver metastases: DWI alone or combined with MDCT is no substitute for Gd-EOB-DTPA-enhanced MRI

Background

Magnetic resonance imaging (MRI) with hepatocyte specific contrast has the highest sensitivity for colorectal liver metastases but comes at high costs and long examination times.

Purpose

To evaluate if preoperative detection of colorectal liver metastases with less resource-consuming diffusion-weighted imaging (DWI) alone or in combination with multidetector computed tomography (MDCT) can compete with gadolinium-etoxybenzyl-diethylenetriaminepentaacetic acid (Gd-EOB-DTPA)-enhanced MRI.

Material and Methods

Forty-four patients with 123 colorectal liver metastases received MDCT and Gd-EOB-DTPA-enhanced MRI including DWI before liver resection for colorectal liver metastases. Five image sets were evaluated by two radiologists. The DWI set consisted of DWI, ADC map, coronal, axial T2-weighted single-shot sequences. The DWI-T2F set contained additionally respiratory-triggered T2-weighted TSE-SPIR sequences. The MDCT set consisted of four-phase MDCT, the MDCT-DWI set also contained DWI. The CE-MRI set contained all MRI sequences including Gd-EOB-DTPA. Reference standards was histopathology and follow-up.

Results

CE-MRI set had highest sensitivity ( P ≤ 0.013) with 95% compared to 72%, 73%, 73%, and 87% the for DWI set, DWI-T2W-FS set, MDCT set, and MDCT-DWI set, respectively. The CE-MRI set had the highest sensitivity ( P≤0.012) for colorectal liver metastases <10 mm with 87% compared to 55%, 52%, 23%, and 58% for the DWI set, DWI-T2W-FS set, MDCT set, and MDCT-DWI set, respectively. The MDCT-DWI set improved sensitivity overall and in size-dependent subgroup analyses compared to the MDCT set ( P ≤ 0.031). The MDCT-DWI set showed the highest specificity of 98% followed by 98%, 98%, 95%, and 88% for the DWI set, DWI-T2W-FS set, MDCT set, and CE-MRI set, respectively.

Conclusion

The less resource and time-consuming DWI sets are inferior to Gd-EOB-DTPA-enhanced MRI for the detection of colorectal liver metastases. Gd-EOB-DTPA-enhanced MRI with its excellent sensitivity should be the preferred preoperative modality when meticulous lesion identification is essential. Combination of DWI with MDCT improved significantly sensitivity compared to each modality alone.

Whole-body MRI added to gadoxetic acid-enhanced liver MRI for detection of extrahepatic disease in patients considered eligible for hepatic resection and/or local ablation of colorectal cancer liver metastases

Background

Fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) can detect extrahepatic disease before local treatment of colorectal liver metastases.

Purpose

To investigate if whole-body magnetic resonance imaging (MRI) added to gadoxetic acid liver MRI could replace FDG-PET/CT for detection of extrahepatic disease in patients with colorectal liver metastases eligible for hepatic local treatment.

Material and Methods

This health-research-ethics-committee-approved prospective consecutive diagnostic accuracy study with written informed consent analyzed 79 cases included between 29 June 2015 and 7 February 2017. Whole-body MRI covering the thorax, abdomen, and pelvis and FDG-PET/CT including contrast-enhanced CT was performed 0–3 days before local treatment of liver metastases. Whole-body MR images were read independently by two readers. FDG-PET/CT images were read independently by two pairs of readers. Histopathology and follow-up imaging were used as reference standard. Sensitivities and specificities were calculated and compared including noninferiority analysis.

Results

Seventy-five malignant lesions and 419 benign lesions were confirmed. Sensitivities of both PET/CT reader pairs 1 and 2 (56.7 and 67.9%) and MRI reader 2 (63.0%) were significantly higher than that of MRI reader 1 (42.7) (P<0.04). Specificities of both PET/CT reader pairs 1 and 2 (92.5 and 92.4%) and MRI reader 1 (91.1%) were significantly higher than that of MRI reader 2 (86.3%) ( P < 0.02). Sensitivity of MRI reader 2 was non-inferior compared to PET/CT reader pair 1. Specificities of both MRI readers were non-inferior to both PET/CT reader pairs.

Conclusion

For detection of extrahepatic disease in patients with colorectal liver metastases, whole-body MRI was non-inferior to FDG-PET/CT for some reader combinations. However, reader-independent non-inferiority could not be demonstrated.