Adequate preoperative staging rarely leads to a change of intraoperative strategy in patients undergoing surgery for colorectal cancer liver metastases

Utility of combined gadoxetic acid and ferumoxytol-enhanced liver MRI for preoperative detection of colorectal cancer liver metastases: a pilot study

Background

Colorectal cancer (CRC) is the second-leading cause of cancer-related death worldwide and resection of CRC metastases confined to the liver is the treatment of choice when feasible. Ferumoxytol is an off-label contrast agent that opacifies vasculature and may be helpful in distinguishing metastases from small hemangiomas and blood vessels on gadoxetic acid-enhanced magnetic resonance imaging (MRI).

Purpose

To compare the diagnostic accuracy of MRI using a standard gadoxetic acid protocol and a combined gadoxetic acid/ferumoxytol protocol in patients with suspected colorectal hepatic metastases.

Material and Methods

In this institutional review board-approved, single-institution, retrospective study, eight patients underwent gadoxetic acid-enhanced liver MRI, supplemented with additional T1-weighted ferumoxytol enhanced sequences. Two radiologists in consensus identified all metastases using all available sequences, which served as the reference standard. Two different radiologists reviewed each exam twice, once using the standard protocol and once with additional ferumoxytol sequences. The detection rate was estimated as the predicted probability of a metastasis along with the 95% confidence interval (CI) using hierarchical logistic regression models.

Results

A total of 49 metastases were identified. The mean diameter was 10 mm, measured in greatest axial dimension (median=7 mm; range=2–70 mm). Readers 1 and 2 had detection rates of 69.6% (95% CI = 48.2–85.0) and 53.1% (95% CI = 35.2–70.3) for gadoxetic acid alone and 98.0% (95% CI = 86.3–99.7) and 83.5% (95% CI = 59.3–94.7) for combined protocol.

Conclusion

In this preliminary investigation, adding ferumoxytol-enhanced sequences to gadoxetic acid liver MRI protocol increased the detection rate of CRC hepatic metastases and may aid in preoperative decision making.

Narrow-band Imaging Examination of Microvascular Architecture of Subcapsular Hepatic Tumors

BACKGROUND

Intraoperative ultrasonography is the golden standard method for evaluation of liver tumors during hepatectomy. However, in laparoscopic surgery, accurate assessment of tumors may be difficult, particularly if the lesion is located nearby the liver surface because of the challenges in handling the intraoperative ultrasound and the lack of tactile sensation. In this study, we demonstrate the preliminary results of examining the microvascular architecture of subcapsular hepatic tumors using laparoscopic narrow-band imaging (NBI) to distinguish between malignant and benign tumors.

MATERIALS AND METHODS

Thirty-five lesions were examined by NBI during laparoscopic hepatectomy for the presence of abnormal microvasculature on the liver surface in relation to hepatic tumors from January 2016 to August 2018. The microvascular findings were correlated with tumor localization and pathological diagnosis.

RESULTS

The 35 examined nodules included 11 hepatocellular carcinoma, 18 colorectal liver metastasis, and six benign nodules. The mean tumor diameter was 26.3 (3-70) mm, and the distance from the liver surface to the tumor was 0.5 (0-5) mm. Microvessels on the liver surface were clearly visualized by NBI, consistent with malignant tumor localization. The tumors were thoroughly examined for the presence of three pathological microvascular features (enlargement, tortuosity, and heterogeneity). Abnormal microvascular patterns were found in 90.9% of hepatocellular carcinoma and 77.8% of colorectal liver metastasis, whereas neither normal sites nor benign lesions displayed microvascular abnormality.

CONCLUSIONS

This study suggests that observing the microvessel image on the liver surface by NBI could be useful in tumor localization and differentiation between benign and malignant lesions.

Routine Intraoperative Ultrasound for the Detection of Liver Metastases during Resection of Primary Colorectal Cancer - A Systematic Review

During the discovery of ColoRectal Cancer (CRC), 20% to 30% of patients have synchronous liver metastases. Ten to 30% of patients have non-evidence of Liver Metasteses (LM) following preoperative imaging such as Contrast-Enhanced Ultrasound (CE-US), multi-slice Contrast-Enhanced Computed Tomography (CE-CT), Contrast-Enhanced Magnetic Resonance Imaging (CE-MRI), and Positron Emission Tomography-Computed Tomography (PET-CT). Today, IntraOperative UltraSound (IOUS) in open surgery and Laparoscopic UltraSound (LUS) in laparoscopic or robotic surgery are considered the "gold standard" for detecting liver metastases. The object of this review is to demonstrate the higher sensitivity and specificity of IOUS and LUS in the detection rate of liver metastases.

Limited detection of small (≤ 10 mm) colorectal liver metastasis at preoperative CT in patients undergoing liver resection

OBJECTIVE

To retrospectively determine the sensitivity of preoperative CT in the detection of small (≤ 10 mm) colorectal liver metastasis (CRLM) nodules in patients undergoing liver resection.

METHODS

The institutional review board approved the study and waived informed consent. We included 461 pathologically confirmed CRLM nodules in 211 patients (including 71 women; mean age, 66.4 years) who underwent 229 liver resections following abdominal CT. Prior to 163 resections, gadoxetic acid-enhanced liver MR imaging was also performed. Nodules were matched between pathology reports and prospective CT reports following a predefined algorithm. Per-nodule sensitivity of CT was calculated by nodule-size category. Generalized estimating equations were used to adjust for within-case correlation.

RESULTS

Fourteen nodule sizes were missing in the pathology report. Nodules of 1-5 mm and 6-10 mm accounted for 8.1% (n = 36) and 23.5% (n = 105) of the remaining 447 nodules, and the number of nodules gradually decreased as nodule size increased beyond 10 mm. The overall sensitivity of CT was 81.2% (95% confidence interval, 77.1%, 85.2%; 365/461). The sensitivity was 8% (0%, 17%; 3/36), 55% (45%, 65%; 59/105), 91%, 95%, and 100% for nodules of 1-5 mm, 6-10 mm, 11-15 mm, 16-20 mm, and >20 mm, respectively. The nodule-size distribution was similar between resections undergoing gadoxetic acid-enhanced MR imaging and those not undergoing the MR imaging.

CONCLUSION

CT has limited sensitivity for nodules of ≤ 10 mm and particularly of ≤ 5 mm.

Diagnostic accuracy of confocal laser endomicroscopy for the characterization of liver nodules

OBJECTIVES

Probe-based confocal laser endomicroscopy (pCLE) is a promising new imaging technique enabling in-vivo analysis of tissues at the cellular level, in real time. The aim of the present study was to prospectively evaluate the feasibility and accuracy of indocyanine green-aided pCLE for the diagnosis of malignant liver nodules.

PATIENTS AND METHODS

From October 2014 to July 2015, liver specimens from 30 consecutive patients were analyzed ex vivo using pCLE directly after resection, with indocyanine green as contrast agent. The final diagnosis was obtained histologically, as per standard of care. In phase 1, a pathologist and a physicist established pCLE image criteria to distinguish normal parenchyma, malignant nodules, and metastases that had completely responded to chemotherapy. In phase 2, a pathologist and a surgeon reviewed selected videos retrospectively to assess the effectiveness of these.

RESULTS

In phase 1, the healthy nodules were characterized by fluorescent hepatocytes with nonfluorescent nuclei and the malignant nodules were identified as strongly fluorescent, irregular cancer-cell clusters. The extracellular matrix was substantially less fluorescent compared with the cancerous clusters of cells. After chemotherapy, a very dense and strongly fluorescent fibrosis replaced tubular structures of cancerous cells. The retrospective evaluation in phase 2 resulted in 78 and 100% sensitivity, 100 and 89% specificity, 90 and 100% positive predictive value, and 90 and 100% negative predictive value for the surgeon and the pathologist, respectively, for the detection of malignant nodules.

CONCLUSION

This series emphasized that characterization of liver metastases is possible with pCLE, with high performance results.

Intraoperative Contrast-Enhanced Ultrasound in Colorectal Liver Metastasis Surgery Improves the Identification and Characterization of Nodules

INTRODUCTION

The sensitivity of preoperative assessment of colorectal liver metastases (CRLM) ranges from 74 to 80%. Intraoperative ultrasound (IOUS) associated with contrast-enhanced intraoperative ultrasound (CE-IOUS) may be able to improve this. Thus, the aims of this study were to assess the value of IOUS and CE-IOUS for the surgical approach and to determine risk factors both for the detection of new nodules and for the modification of the surgical strategy.

MATERIALS AND METHODS

Forty-three patients who underwent CRLM surgery were included. These patients had an MRI in the 8 weeks preceding surgery and benefited from intraoperative IOUS and CE-IOUS.

RESULTS AND DISCUSSION

The use of IOUS/CE-IOUS permitted the identification of 43 additional lesions and an improved characterization of nodules in 23 patients with a resulting modification of surgical strategy. Lesions were down-staged in six patients and up-staged in six patients. Chemotherapy (p = 0.02) and the presence of nodules in the left lobe (p = 0.04) were predictive factors for finding new nodules at IOUS/CE-IOUS. The discovery of a new nodule systematically modified surgical management. IOUS/CE-IOUS improved intraoperative management of liver metastases. The techniques enable pertinent modification of surgical resections and a reduction of residual lesions.

Minimally Invasive Liver Surgery for Hepatic Colorectal Metastases

Minimally invasive surgery has been cautiously introduced in surgical oncology over the last two decades due to a concern of compromised oncological outcomes. Recently, it has been adopted in liver surgery for colorectal metastases. Colorectal cancer is a major cause of cancer-related death in the USA. In addition, liver metastasis is the most common site of distant disease and its resection improves survival. While open resection was the standard of care, laparoscopic liver surgery has become the standard of care for minor liver resections. Laparoscopic liver surgery provides equivalent oncological outcomes with better perioperative results compared to open liver surgery. Robotic liver surgery has been introduced as it is believed to overcome some of the limitations of laparoscopy. Finally, laparoscopic radio-frequency ablation and microwave coagulation can be used as adjuncts in minimally invasive surgery to complement or replace surgical resection when not possible.

Usefulness of intraoperative ultrasonography in liver resections due to colon cancer metastasis

INTRODUCTION

Intraoperative ultrasonography (IOUS) of the liver has been used both as an aid for intraoperative anatomical definition and for the detection of new lesions. The present study aimed to evaluate the impact of IOUS and to identify factors that can predict the detection of new lesions intraoperatively.

METHODS

In this observational and prospective study, with a cross-sectional design, patients with colorectal cancer metastases who underwent hepatectomy were selected. Abdominal computed tomography, magnetic resonance imaging, and positron emission tomography were the preoperative evaluation tests. All patients underwent IOUS performed by the same surgeon. The intraoperative findings were compared with the preoperative tests results.

RESULTS

In total, 56 hepatectomies were evaluated. Half of the patients were men, with a mean age of 57 (30-85) years. New lesions were found intraoperatively in 12 patients (21.4% of cases) and were detected on both palpation and ultrasonography in 11 of these patients. Ultrasonography helped to revise the surgical plans by providing additional information in 35.7% of cases. On multivariate analysis, the presence of more than 4 preoperative nodules was predictive of the intraoperative occurrence of new lesions.

CONCLUSIONS

IOUS remains the only way to evaluate the relationships between tumors, liver vascular structures, and bile ducts intraoperatively. Alone, IOUS was not useful for identifying new lesions intraoperatively, as all new lesions were also detected on palpation. The number of lesions diagnosed on preoperative tests influenced the probability of identifying new lesions intraoperatively. There may be additional influential factors.

Is intraoperative ultrasound still useful for the detection of colorectal cancer liver metastases?

BACKGROUND

Debate on the optimal mode of preoperative imaging in the management of colorectal liver metastases (CRLM) is ongoing and, despite its longstanding use, the precise role of intraoperative ultrasonography (IOUS) is not well established. This study evaluates the impact of IOUS in the era of high-quality, cross-sectional imaging techniques.

METHODS

All patients who underwent liver resection for CRLM in a tertiary care referral centre from January 2006 to December 2013 were included. All patients were submitted to computed tomography (CT) and/or liver magnetic resonance imaging (MRI) before surgery. Intraoperative US was performed mainly to detect previously non-diagnosed tumours that would change the surgical strategy.

RESULTS

A total of 225 liver resections were performed. Liver MRI and CT scans were available for 202 patients (89.8%) and 225 patients (100%), respectively. Radiological reports recorded 632 liver tumours in 219 patients (i.e. 2.9 lesions per patient). The median time between preoperative liver MRI and surgical resection was 36 days. Intraoperative inspection, palpation and US found 20 additional lesions in 18 patients (8.0%), in three of whom lesions were diagnosed only on IOUS (1.4%). Overall, only 12 of the 20 lesions were malignant.

CONCLUSIONS

Although CT and liver MRI are commonly used, IOUS alone allows the discovery of a few additional lesions that result in a change of surgical strategy in 1.4% of cases.

Preoperative evaluation of colorectal liver metastases: comparison between gadoxetic acid-enhanced 3.0-T MRI and contrast-enhanced MDCT with histopathological correlation

OBJECTIVES

The aim of this prospective study was to compare the diagnostic performance of 64-row MDCT and gadoxetic-acid-enhanced MRI at 3.0 T in patients with colorectal liver metastases in correlation with histopathological findings.

METHODS

Lesions detected at MDCT and MRI were interpreted by three blinded readers and compared with histopathological workup as the term of reference. Two subgroups of lesions were additionally evaluated: (1) metastases smaller than 10 mm and (2) lesions in patients with and without steatosis of the liver, assessed histopathologically.

RESULTS

Surgery and histopathological workup revealed 81 colorectal liver metastases in 35 patients and diffuse metastatic involvement in 3 patients. In a lesion-by-lesion analysis, significant sensitivity differences could only be found for reader 1 (P = 0.035) and reader 3 (P = 0.003). For segment-based evaluation, MRI was more sensitive only for reader 3 (P = 0.012). The number of false-positive results ranged from 3 to 12 for MDCT and 8 to 11 for MRI evaluation. In the group of small lesions, the sensitivity differed significantly between both methods (P = 0.003). In patients with hepatic steatosis, MRI showed a trend toward better performance than MDCT, but without statistical performance.

CONCLUSIONS

The 3.0-T MRI with liver-specific contrast agents is the preferred investigation in the preoperative setting, especially for the assessment of small colorectal liver metastases.

KEY POINTS

• Potential surgical treatment requires accurate radiological assessment of colorectal liver metastases • Magnetic resonance imaging with gadoxetic acid is the preferred imaging investigation. • MRI is better than multidetector CT for detecting small liver metastases.

Selection for hepatic resection of colorectal liver metastases: expert consensus statement

Hepatic resection offers a chance of a cure in selected patients with colorectal liver metastases (CLM). To achieve adequate patient selection and curative surgery, (i) precise assessment of the extent of disease, (ii) sensitive criteria for chemotherapy effect, (iii) adequate decision making in surgical indication and (iv) an optimal surgical approach for pre-treated tumours are required. For assessment of the extent of the disease, contrast-enhanced computed tomography (CT) and/or magnetic resonance imaging (MRI) with gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA) is recommended depending on the local expertise and availability. Positron emission tomography (PET) and PET/CT may offer additive information in detecting extrahepatic disease. The RECIST criteria are a reasonable method to evaluate the effect of chemotherapy. However, they are imperfect in predicting a pathological response in the era of modern systemic therapy with biological agents. The assessment of radiographical morphological changes is a better surrogate of the pathological response and survival especially in the patients treated with bevacizumab. Resectability of CLM is dependent on both anatomic and oncological factors. To decrease the surgical risk, a sufficient volume of liver remnant with adequate blood perfusion and biliary drainage is required according to the degree of histopathological injury of the underlying liver. Portal vein embolization is sometimes required to decrease the surgical risk in a patient with small future liver remnant volume. As a complete radiological response does not signify a complete pathological response, liver resection should include all the site of a tumour detected prior to systemic treatment.

Non-invasive diagnosis of focal liver lesions: an individualized approach

Modern cross-sectional imaging with multidetector computed tomography (MDCT) or magnetic resonance imaging (MRI) often reveals small focal liver lesions, which puts pressure on the reporting radiologist to characterize these tiny lesions. On the other hand, in patients with underlying diffuse liver disease, such as cirrhosis or severe steatosis, the detection of focal liver lesions can be quite difficult. Strategies for optimal detection and characterization of focal liver lesions should be developed according to the clinical situation, the likelihood of malignant disease and the presence of underlying diffuse liver disease. The presence or absence of a clinical history of cancer determines the algorithm for further characterization: work-up with contrast-enhanced MRI, biopsy or follow-up. In patients with chronic liver disease, recent guidelines on the detection of hepatocellular carcinoma (HCC) favour the use of multiphasic MRI or MDCT, which allows confident diagnoses of HCC >1 cm. For lesions <1 cm in chronic liver disease, follow-up is recommended. In patients with moderate to severe steatosis, contrast-enhanced MDCT has low diagnostic yield for the detection of liver lesions; contrast-enhanced MRI is far superior. This review describes successful strategies for the detection and characterization of focal liver lesions in different clinical scenarios.

Gadoxetic acid-enhanced 3.0 T MR imaging versus multidetector-row CT in the detection of colorectal metastases in fatty liver using intraoperative ultrasound and histopathology as a standard of reference

OBJECTIVE

To compare the diagnostic value of gadoxetic acid-enhanced MRI at 3.0 T with 64-row MDCT in the detection of colorectal liver metastases in diffuse fatty infiltration of the liver after neoadjuvant chemotherapy.

METHODS

Twenty-three patients with colorectal liver metastases and at moderate to severe steatosis (25-90%) underwent prospectively preoperative tri-phasic MDCT (Somatom Sensation 64, Siemens) and gadoxetic acid-enhanced MRI (3-T Magnetom Trio, Siemens). All patients underwent surgical resection of liver metastases. Intraoperative ultrasound (IOUS) was carried out, which served as the standard of reference, together with histopathology.

RESULTS

Overall, 68 metastases (range, 0.4-6 cm; 31/68 metastases [46%] ≤ 1 cm) were found at histology. MDCT detected 49/68 lesions (72%), and MRI 66/68 (97%, p < 0.001). For lesions ≤ 1 cm, MDCT detected only 13/31 (41.9%) and MRI 29/31 (93%, p < 0.001). Eight false-positive lesions were detected by MDCT, seven small lesions by MRI. There was no statistically significant difference between the two modalities in the detection of lesions > 1 cm (p = 0.250). IOUS detected all metastases and revealed two false-positive diagnoses.

CONCLUSION

Gadoxetic acid-enhanced 3.0 T MRI is superior to 64-row MDCT in detecting colorectal liver metastases ≤ 1 cm during preoperative staging in patients with liver steatosis. A combination of MRI and IOUS may further improve the outcome of surgical treatment.

Minimally invasive evaluation and treatment of colorectal liver metastases

Minimally invasive techniques used in the evaluation and treatment of colorectal liver metastases (CRLMs) include ultrasonography (US), computed tomography, magnetic resonance imaging, percutaneous and operative ablation therapy, standard laparoscopic techniques, robotic techniques, and experimental techniques of natural orifice endoscopic surgery. Laparoscopic techniques range from simple staging laparoscopy with or without laparoscopic intraoperative US, through intermediate techniques including simple liver resections (LRs), to advanced techniques such as major hepatectomies. Hereins, we review minimally invasive evaluation and treatment of CRLM, focusing on a comparison of open LR (OLR) and minimally invasive LR (MILR). Although there are no randomized trials comparing OLR and MILR, nonrandomized data suggest that MILR compares favorably with OLR regarding morbidity, mortality, LOS, and cost, although significant selection bias exists. The future of MILR will likely include expanding criteria for resectability of CRLM and should include both a patient registry and a formalized process for surgeon training and credentialing.

Computed tomographic colonography in preoperative evaluation of colorectal tumors: a prospective study

Background

This study aimed to assess the usefulness of computed tomographic colonography (CTC) in preoperative evaluation of colorectal tumors and the entire bowel including endoscopically inaccessible regions.

Methods

Colonoscopy and CTC were performed for 49 patients. The tumor and the entire colon were assessed, and the results were compared with colonoscopy. The extraluminal findings of CTC were compared with contrast-enhanced computed tomography (CT) of the abdomen and the pelvis in 33 patients. All these patients had undergone surgery. A comparison of results for tumor node metastasis classification between CTC, CT, and histopathology was performed.

Results

Exploration of the entire colon was possible for 89.8% of the patients using CTC and 49.0% of the patients using colonoscopy. Bowel cleansing was assessed as worse with CTC. In the evaluation of tumor location and morphologic type, CTC was congruent with colonoscopy. Colonoscopy enabled approximate tumor size and volume to be evaluated for only 59.2% (29/49) and 30.6% (15/49) of patients, respectively, whereas CTC enabled evaluation of all 48 (100.0%) visualized tumors. Wall thickening, outer contour, and suspected infiltration of surrounding tissues and organs are impossible to determine with colonoscopy but can be determined with CTC. Using CTC, two additional tumors were found proximate to occlusive masses in endoscopically inaccessible regions.

Conclusion

Computed tomographic colonography is a useful method for diagnosing colorectal tumors. It allows the clinician to diagnose tumor, determine local tumor progression, and detect synchronous lesions in the large bowel including endoscopically inaccessible regions.

Factors determining the sensitivity of intraoperative ultrasonography in detecting colorectal liver metastases in the modern era

BACKGROUND

With improved preoperative cross-sectional imaging, the added clinical value of intraoperative ultrasonography (IOUS) in the detection of colorectal liver metastases (CRLM) is unclear. Specifically, the ability of IOUS to detect additional liver metastases during surgery and its relationship between clinical and lesion specific ultrasonographic characteristics remains ill-defined. The purpose of the current study was to determine the association of clinical parameters and tumor echogenicity with the ability of IOUS to detect occult CRLM.

MATERIALS AND METHODS

A total of 213 patients undergoing surgical exploration and IOUS for CRLM between 1998 and 2009 were included in the study. All patients underwent preoperative multidetector computed tomography (CT) imaging and lesion detection was compared with those identified by IOUS. In addition, early (<6 months) intrahepatic recurrence was used as a surrogate for residual disease (e.g., metastases that were undetected on initial IOUS). The influence of various characteristics on the rate in which additional metastases were detected and the rate of early intrahepatic recurrence was examined.

RESULTS

Overall, IOUS detected additional liver metastases in 10% of patients (n = 22). Detection of additional metastases was significantly higher in patients with multiple (≥4) tumors (P < 0.001) and hypoechoic tumors (P = 0.007). Of 153 patients undergoing resection only, 17 (11%) had an early intrahepatic recurrence. This was more common in patients with isoechoic metastases during IOUS (P = 0.03).

CONCLUSIONS

Even with the use of modern cross-sectional preoperative imaging, IOUS detects additional liver metastases in 10% of patients. In addition, the sensitivity of IOUS for detecting occult CRLM is highly dependent on the number and echogenicity of detected tumors.

Synchronous colorectal liver metastases: is it time to reconsider traditional paradigms of management?

BACKGROUND

Patients with synchronous colorectal liver metastases (CLM) are typically treated with initial colorectal resection followed by arbitrary and prolonged courses of chemotherapy. Partial hepatectomy is considered only for patients without interval disease progression. This review describes the rationale for this treatment approach and the recent developments suggesting that this management paradigm should be reconsidered.

RESULTS

Because asymptomatic colorectal cancer often does not lead to complications, and given the potential benefit of chemotherapy in downsizing unresectable to resectable liver disease, most patients with asymptomatic primary tumors and unresectable synchronous CLM should be first treated with chemotherapy. In contrast, initial hepatic resection should be considered for resectable synchronous CLM. Survival benefits from prehepatectomy chemotherapy have not been established. Several reports demonstrate morbidity after hepatic resection from extended durations of irinotecan- and/or oxaliplatin-based prehepatectomy chemotherapy. Although shorter treatment periods may not have these deleterious effects on subsequent hepatic resection, prospective studies reveal that most patients with supposedly aggressive disease with short treatment durations will not be identified. Moreover, a complete radiologic response to prehepatectomy chemotherapy is not only rare but also does not equate with a complete pathological response. Finally, several studies suggest that simultaneous colorectal and minor hepatic resections can performed safely with benefits in total morbidity when compared with traditional staged procedures.

CONCLUSIONS

The traditional treatment paradigm centering on the utility of prehepatectomy chemotherapy for resectable synchronous CLM should be reconsidered. Recent developments underscore the need for prospective randomized controlled trials evaluating the optimal timing of hepatectomy relative to chemotherapy.