Incremental value of arterial and equilibrium phase compared to hepatic venous phase CT in the preoperative staging of colorectal liver metastases: an evaluation with different reference standards

Standardized diagnosis of gastrointestinal tumors: an update regarding the situation in Germany

To evaluate the current status of the diagnosis of gastrointestinal tumors in Germany by means of a survey of the oncological imaging working group of the German Radiological Society (DRG) with a focus on the CT protocols being used.Radiologists working in outpatient or inpatient care in Germany were invited. The survey was conducted between 10/2022 and 06/2023 using the SurveyMonkey web tool. Questions related to gastrointestinal cancer were asked with regard to the commonly used imaging modalities, body coverage, and contrast agent phases in CT as well as the use of oral or rectal contrast. The results of the survey were analyzed using descriptive statistics.Clear differences were identified regarding the acquired contrast phases in relation to the place of work - outpatient care, smaller hospitals, maximum care hospitals, or university hospitals. Variances were also recognized regarding oral and rectal contrast. Based on the results and international guidelines, proposals for CT protocols were derived.CT protocols in Germany show a heterogeneous picture regarding acquired contrast phases, as well as oral and rectal contrast for the staging of gastrointestinal cancer. Clear recommendations in the respective guidelines would aid in quality assurance and comparability between different centers. · The examination protocols for the staging of gastrointestinal tumors are heterogeneous in Germany.. · The application of oral and rectal contrast is handled differently at the various radiological centers.. · Standardization of imaging should be targeted.. · Gerwing M, Ristow I, Afat S et al. Standardized diagnosis of gastrointestinal tumors: an update regarding the situation in Germany. Rofo 2025; 197: 657-668.

Equilibrium phase images of the liver using a contrast-enhancement boost instead of the portal vein phase

BACKGROUND

Three-phase dynamic computed tomography imaging is particularly useful in the liver region. However, dynamic imaging with contrast media has the disadvantage of increased radiation exposure due to multiple imaging sessions. We hypothesized that the contrast enhancement boost (CE-boost) technique could be used to enhance the contrast in equilibrium phase (EP) images and produce enhancement similar to that of portal vein phase (PVP) images, and if this is possible, EP imaging could play the same role as PVP imaging. We also speculated that this might allow the conversion of three-phase dynamic imaging to biphasic dynamic imaging, reducing patients’ radiation exposure.

AIM

To determine if the CE-boost of EP, CE-boost (EP) is useful compared to a conventional image.

METHODS

We retrospectively analyzed the cases of 52 patients who were diagnosed with liver cancer between January 2016 and October 2022 at our institution. From these computed tomography images, CE-boost images were generated from the EP and plane images. We compared the PVP, EP, and CE-boost (EP) for blood vessels and hepatic parenchyma based on the contrast-to-noise ratio (CNR), signal-to-noise ratio, and figure-of-merit (FOM). Visual assessments were also performed for vessel visualization, lesion conspicuity, and image noise.

RESULTS

The CE-boost (EP) images showed significant superiority compared to the PVP images in the CNR, signal-to-noise ratio, and FOM except regarding the hepatic parenchyma. No significant differences were detected in CNR or FOM comparisons within the hepatic parenchyma (P = 0.62, 0.67). The comparison of the EP and CE-boost (EP) images consistently favored CE-boost (EP). Regarding the visual assessment, the CE-boost (EP) images were significantly superior to the PVP images in lesion conspicuity, and the PVP in image noise. The CE-boost (EP) images were significantly better than the EP images in the vessel visualization of segmental branches of the portal vein and lesion conspicuity, and the EP in image noise.

CONCLUSION

The image quality of CE-boost (EP) images was comparable or superior to that of conventional PVP and EP. CE-boost (EP) images might provide information comparable to the conventional PVP.

Defining MRI Superiority over CT for Colorectal and Neuroendocrine Liver Metastases

BACKGROUND

We compared CT and MRI for staging metastatic colorectal or neuroendocrine liver metastases (CRLMs and NELMs, respectively) to assess their impact on tumor burden.

METHODS

A prospectively maintained database was queried for patients who underwent both imaging modalities within 3 months, with two blinded radiologists (R1 and R2) independently assessing the images for liver lesions. To minimize recall bias, studies were grouped by modality, and were randomized and evaluated separately.

RESULTS

Our query yielded 76 patients (42 CRLMs; 34 NELMs) with low interrater variability (intraclass correlation coefficients: CT = 0.941, MRI = 0.975). For CRLMs, there were no significant differences in lesion number or size between CT and MRI. However, in NELMs, Eovist®-enhanced MRI detected more lesions (R1: 14.3 vs. 12.1, p = 0.02; R2: 14.4 vs. 12.4, p = 0.01) and smaller lesions (R1: 5.7 vs. 4.4, p = 0.03; R2: 4.8 vs. 2.9, p = 0.02) than CT.

CONCLUSIONS

CT and MRI are equivalent for CRLMs, but for NELMs, MRI outperforms CT in detecting more and smaller lesions, potentially influencing treatment planning and surgery.

Imaging of Colorectal Liver Metastasis

Colorectal cancer (CRC) is one of the most common cancers in the world. The most important determinant of survival and prognosis is the stage and presence of metastasis. The liver is the most common location for CRC metastasis. The only curative treatment for CRC liver metastasis (CRLM) is resection; however, many patients are ineligible for surgical resection of CRLM. Locoregional treatments such as ablation and intra-arterial therapy are also available for patients with CRLM. Assessment of response after chemotherapy is challenging due to anatomical and functional changes. Antiangiogenic agents such as bevacizumab that are used in the treatment of CRLM may show atypical patterns of response on imaging. It is vital to distinguish patterns of response in addition to toxicities to various treatments. Imaging plays a critical role in evaluating the characteristics of CRLM and the approach to treatment. CT is the modality of choice in the diagnosis and management of CRLM. MRI is best used for indeterminate lesions and to assess response to intra-arterial therapy. PET-CT is often utilized to detect extrahepatic metastasis. State-of-the-art imaging is critical to characterize patterns of response to various treatments. We herein review the imaging characteristics of CRLM with an emphasis on imaging changes following the most common CRLM treatments.

Multimodality Approach in Detection and Characterization of Hepatic Metastases

Early detection of liver metastases is important in patients with known primary malignancies. This plays an important role in treatment planning and impacts on further management of certain primary malignancies.

Magnetic resonance imaging (MRI), computed tomography (CT), and positron emission tomography-computed tomography scans are reported to have high accuracy in the diagnosis of intrahepatic lesions. MRI in particular has the advantages of its high tissue sensitivity and its multiparametric approach.

Hepatic metastatic lesions have considerable overlap in their radiological appearance, and in this article the imaging appearance of various hepatic metastasis and approach is described.

Liver metastases: Detection and staging

The liver is more often involved with metastatic disease than primary liver tumors. The accurate detection and characterization of liver metastases are crucial since patient management depends on it. The imaging options, mainly consisting of contrast-enhanced ultrasound (CEUS), multidetector computed tomography (CT), magnetic resonance imaging (MRI) with diffusion-weighted imaging (DWI), extra-cellular contrast media and liver-specific contrast media as well as positron emission tomography/computed tomography (PET/CT), are constantly evolving. PET/MRI is a more recent hybrid method and a topic of major interest concerning liver metastases detection and characterization. This review gives a brief overview about the spectrum of imaging findings and focus on an update about the performance, advantages and potential limitations of each modality as well as current developments and innovations.

Liver CT for vascular mapping during radioembolisation workup: comparison of an early and late arterial phase protocol

OBJECTIVES

To compare right gastric (RGA) and segment 4 artery (A4) origin detection rates during radioembolisation workup between early and late arterial phase liver CT protocols.

METHODS

100 consecutive patients who underwent liver CT between May 2012-January 2015 with early or late arterial phase protocol (n = 50 each, 10- vs. 20-s post-threshold delay) were included. RGA/A4 origin detection rates, assessed by two raters, and contrast-to-noise ratio (CNR) of the hepatic artery relative to the portal vein were compared between the protocols.

RESULTS

The first-second rater scored the RGA origin as visible in 58-65 % (specific proportion of agreement 82 %, κ = 0.62); A4 origin in 96-89 % (94 %, κ = 0.54). Thirty-six percent of RGA origins not detectable by DSA were identified on CT. Origin detection rates were not significantly different for early/late arterial phases. Mean CNR was higher in the early arterial phase protocol (1.7 vs. 1.2, p < 0.001).

CONCLUSION

A 10-s delay arterial phase CT protocol does not significantly improve detection of small intra- and extrahepatic branches. RGA origin detection requires further optimization, whereas A4/MHA origin detection is adequate, with good inter-rater reproducibility. CT remains important for preprocedural planning, because it may reveal arterial anatomy not discernible on DSA.

KEY POINTS

• An early arterial phase does not significantly improve RGA and A4/MHA origin detection. • RGA origin detection (58-65 %) on CT is still suboptimal. • 36 % of RGA origins undetectable on DSA can be identified on CT. • A4/MHA origin detection (89-96 %) on CT is excellent. • Inter-rater reproducibility is good for RGA and A4/MHA origin detection on CT.

Non-invasive diagnostic imaging of colorectal liver metastases

Colorectal cancer is one of the few malignant tumors in which synchronous or metachronous liver metastases [colorectal liver metastases (CRLMs)] may be treated with surgery. It has been demonstrated that resection of CRLMs improves the long-term prognosis. On the other hand, patients with un-resectable CRLMs may benefit from chemotherapy alone or in addition to liver-directed therapies. The choice of the most appropriate therapeutic management of CRLMs depends mostly on the diagnostic imaging. Nowadays, multiple non-invasive imaging modalities are available and those have a pivotal role in the workup of patients with CRLMs. Although extensive research has been performed with regards to the diagnostic performance of ultrasonography, computed tomography, positron emission tomography and magnetic resonance for the detection of CRLMs, the optimal imaging strategies for staging and follow up are still to be established. This largely due to the progressive technological and pharmacological advances which are constantly improving the accuracy of each imaging modality. This review describes the non-invasive imaging approaches of CRLMs reporting the technical features, the clinical indications, the advantages and the potential limitations of each modality, as well as including some information on the development of new imaging modalities, the role of new contrast media and the feasibility of using parametric image analysis as diagnostic marker of presence of CRLMs.

Evolution of imaging in rectal cancer: multimodality imaging with MDCT, MRI, and PET

Magnetic resonance imaging (MRI), multidetector computed tomography (MDCT), and positron emission tomography (PET) are complementary imaging modalities in the preoperative staging of patients with rectal cancer, and each offers their own individual strengths and weaknesses. MRI is the best available radiologic modality for the local staging of rectal cancers, and can play an important role in accurately distinguishing which patients should receive preoperative chemoradiation prior to total mesorectal excision. Alternatively, both MDCT and PET are considered primary modalities when performing preoperative distant staging, but are limited in their ability to locally stage rectal malignancies. This review details the role of each of these three modalities in rectal cancer staging, and how the three imaging modalities can be used in conjunction.

Patient tailored resection planning in patients undergoing liver surgery for colorectal liver metastases; how and why should you do it?

BACKGROUND

A systematic preoperative evaluation to determine the individual resection strategy in patients with colorectal liver metastases (CRLM) was assessed as to its clinical value.

PATIENTS AND METHODS

From 2009 to 2011, 75 patients with CRLM who were scheduled for surgery were prospectively included and received an additional preoperative systematic evaluation in the presence of a hepatobiliary radiologist and the hepatobiliary surgeon scheduled to perform the surgery. The following items were assessed in a standardized manner: lesion detection and characterization, presence of extrahepatic disease, vascular anatomy, and resection strategy. Intraoperative findings and histopathological results were prospectively recorded.

RESULTS

Five out of 75 patients were not considered to be eligible for surgery due to additional findings, such as additional metastases or extrahepatic disease. Sensitivity and specificity for detection of individual CRLM were 80.9% (95% CI 75.7-86.1%) and 69.1% (95% CI 59.1-79.1%), respectively. Radical resections were performed in 87.1%. There was one futile laparotomy (1.4%).

CONCLUSION

In patients with colorectal liver metastases, standardized preoperative work-up, with subsequent planning of an individualized resection in a jointed meeting of a hepatobiliary radiologist and the surgeon who will perform the operation, leads to a high level of radical resections and a low number of futile laparotomies.

Preoperative imaging for hepatic resection of colorectal cancer metastasis

Despite recent advances in chemotherapeutic agents, the prognosis for metastatic colon cancer remains poor. Over the past two decades, hepatic metastasectomy has emerged as a promising technique for improving survival in patients with metastatic colon cancer and in some cases providing long-term cure. To maximize safety and efficacy of metastasectomy, appropriate pre-operative imaging is needed. Advancements in computed tomography (CT), magnetic resonance imaging (MRI) and positron emission tomography (PET) have led to improved detection of occult lesions and better definition of surgical anatomy. While CT, PET and MRI have a comparable sensitivity for detection of large liver metastases, MRI excels at detection of subcentimeter liver metastases compared to CT and FDG-PET, especially with the combination of diffusion weighted imaging (DWI) and hepatocyte-specific contrast agents. CT may be useful as a screening modality or in preoperative planning such as volumetric estimation of the remnant liver size or in defining preoperative arterial anatomy for hepatic artery infusion pump placement. While technologic advancements have led to unprecedented image quality and clarity, this does not replace the need for a dedicated, competent radiologist with experience in hepatic imaging.

Preoperative imaging of colorectal liver metastases after neoadjuvant chemotherapy: a meta-analysis

Background

Chemotherapy treatment induces parenchymal changes that potentially affect imaging of CRLM. The purpose of this meta-analysis was to provide values of diagnostic performance of magnetic resonance imaging (MRI), computed tomography (CT), fluorodeoxyglucose positron emission tomography (FDG-PET), and FDG-PET/CT for preoperative detection of colorectal liver metastases (CRLM) in patients treated with neoadjuvant chemotherapy.

Methods

A comprehensive search was performed for original articles published from inception to 2011 assessing diagnostic performance of MRI, CT, FDG-PET, or FDG-PET/CT for preoperative evaluation of CRLM following chemotherapy. Intraoperative findings and/or histology were used as reference standard. For each imaging modality we calculated pooled sensitivities for patients who received neoadjuvant chemotherapy as well as for chemonaive patients, defined as number of malignant lesions detected divided by number of malignant lesions as confirmed by the reference standard.

Results

A total of 11 papers, comprising 223 patients with 906 lesions, were included. Substantial variation in study design, patient characteristics, imaging features, and reference tests was observed. Pooled sensitivity estimates of MRI, CT, FDG-PET, and FDG-PET/CT were 85.7% (69.7–94.0%), 69.9% (65.6–73.9%), 54.5% (46.7–62.1%), and 51.7% (37.8–65.4%), respectively. In chemonaive patients, sensitivity rates were 80.5% (67.0–89.4%) for CT, 81.3% (64.1–91.4%) for FDG-PET, and 71.0% (64.3–76.9%) for FDG-PET/CT. Specificity could not be calculated because of non-reporting of “true negative lesions.”

Conclusion

In the neoadjuvant setting, MRI appears to be the most appropriate imaging modality for preoperative assessment of patients with CRLM. CT is the second-best diagnostic modality and should be used in the absence of MRI. Diagnostic accuracy of FDG-PET and PET-CT is strongly affected by chemotherapy.

Imaging diagnosis of colorectal liver metastases

Rapid advances in imaging technology have improved the detection, characterization and staging of colorectal liver metastases. Multi-modality imaging approach is usually the more useful in diagnosis colorectal liver metastases. It is well established that hepatic resection improves the long-term prognosis of many patients with liver metastases. However, incomplete resection does not prolong survival, so knowledge of the exact extent of intra-hepatic disease is crucially important in determining patient management and outcome. The diagnosis of liver metastases relies first and totally on imaging to decide which patients may be surgical candidates. This review will discuss the imaging options and their appropriate indications. Imaging and evaluating of colorectal liver metastases (CRLM) have been performed with contrast-enhanced ultrasound, multi-detector computed tomography, magnetic resonance imaging (MRI) with extra-cellular contrast media and liver-specific contrast media MRI, and positron emission tomography/computed tomography. This review will concentrate on the imaging approach of CRLM, and also discuss certain characteristics of some liver lesions. We aim to highlight the advantages of each imaging technique, as well as underscoring potential pitfalls and limitations.