Multidetector computed tomography follow-up of hypoattenuating small liver lesions in patients with rectal cancer

Diagnostic yield of contrast-enhanced abdominal staging CT in patients with initially diagnosed breast cancer

PURPOSE

To estimate the diagnostic yield (DY) of abdominal staging CT for detecting breast cancer liver metastasis (BCLM) in patients with initially diagnosed breast cancer and to determine the indications for abdominal staging CT.

METHODS

Patients with newly diagnosed breast cancer who underwent abdominal CT as an initial staging work-up between January 2019 and December 2020 were retrospectively analyzed. DY was calculated and analyzed according to patient age, type of treatments, histologic type, histologic grade, lymphovascular invasion, Ki-67 status, hormone receptor status, subtype, and the American Joint Committee on Cancer anatomical staging.

RESULTS

A total of 2056 patients (mean age, 51 ± 11 years) were included. The DY of abdominal staging CT for detecting BCLM was 1.1 % (22 of 2056). DY was significantly higher in stage III than in stage I or II cancers (3.9 % [18 of 467] vs. 0 % [0 of 412] or 0.4 % [4 of 1158], respectively, p < .001), and in human epidermal growth factor receptor-2 (HER2)-enriched cancers than in luminal or triple negative cancers (2.9 % [16 of 560] vs. 0.4 % [4 of 1090] or 0.5 % [2 of 406], respectively, p < .001).

CONCLUSIONS

The DY of abdominal staging CT for detecting BCLM was low among all patients with initially diagnosed breast cancer. However, although abdominal staging CT for detecting BCLM is probably unnecessary in all patients, it can be clinically useful in patients with stage III or human epidermal growth factor receptor-2-enriched breast cancers.

Indeterminate liver lesions in early stage rectal cancer patients, can they be ignored?

PURPOSE

Small hypo-attenuating indeterminate liver lesions are often encountered at staging Computed Tomography (CT) in early stage rectal cancer patients. This study aims to determine the incidence and prognostic significance of these lesions.

MATERIALS AND METHODS

A single institution's colorectal cancer (CRC) database was searched for patients with early stage rectal cancer, defined as a cT1/2N0 tumor on Magnetic Resonance Imaging (MRI). Abdominal CT scans of these patients were assessed for the presence of liver lesions and according to their morphology they were categorized. Preoperative MRI scans of the liver and abdominal follow-up imaging were assessed to determine whether the liver lesions found at staging CT appeared to be CRC metastases or not.

RESULTS

In a consecutive cohort of 1232 operated CRC patients, 84 patients with early stage rectal cancer (cT1/2N0 on MRI) were identified. Forty-five of the 84 patients (54%) had one or more liver lesions on staging CT with a total of 122 liver lesions. This consisted of 95(78%) indeterminate lesions, 25(20%) cysts and 2(2%) haemangiomas. Preoperative MRI of the liver and regular follow-up imaging revealed no synchronous or metachronous liver metastases in this cohort.

CONCLUSION

Small hypo-attenuating indeterminate lesions of the liver are common in patients diagnosed with early rectal cancer and seem have no clinical significance. Additional pre-operative imaging or follow-up imaging for indeterminate liver lesions in these patients may be unnecessary.

Contrast-enhanced ultrasound can guide the therapeutic strategy by improving the detection of colorectal liver metastases

BACKGROUND & AIMS

CT may miss up to 30% of cases of colorectal liver metastases (CRLMs). We assessed the impact of contrast-enhanced ultrasound (CEUS) on the detection of CRLMs and on changes to the therapeutic strategy; additionally, we assessed the accuracy of CEUS in differentiating unclear focal liver lesions (FLLs) compared to staging-CT.

METHODS

We prospectively analyzed all patients with newly diagnosed and histologically confirmed colorectal cancer (CRC) at our tertiary gastroenterological center between December 2015 and May 2019. CEUS was performed in a total of 296 patients without CRLMs after staging-CT using the contrast agent (SonoVue®). Standard of reference was obtained by MRI or histology to diagnose CRLMs missed by CT. Benign FLLs were confirmed by MRI or follow-up CT (mean follow-up interval: 18 months).

RESULTS

Eight additional CRLMs were detected by CEUS (overall 2.7%; sensitivity 88.9%, specificity 99.0%, positive predictive value 100%, negative predictive value 99.6%). All patients with CRLMs detected only by CEUS were in tumor stage T3/T4 (4.0% additionally detected CRLMs). The number needed to screen to detect 1 additional CRLM by CEUS was 37 in all patients and 24.5 in T3/T4-patients. When results were reviewed by a board-certified radiologist and oncologist, the therapeutic strategy changed in 6 of these 8 patients. Among the 62 patients (20.9%) with unclear FLLs after staging-CT, CEUS determined the dignity (malignant vs. benign) of 98.4% of the FLLs.

CONCLUSION

Overall, CEUS detected 2.7% additional CRLMs (including 4.0% in tumor stage T3/T4) with a significant impact on the oncological therapeutic strategy for 75% of these patients. Patients with tumor stage T3/T4 would particularly benefit from CEUS. We propose CEUS as the first imaging modality for CT-detected lesions of unknown dignity.

LAY SUMMARY

In patients with newly diagnosed colorectal cancer, contrast-enhanced ultrasound (CEUS) detected additional liver metastases after computed tomography (CT). In the majority of these patients, the oncological therapy was changed after obtaining the CEUS results. After staging-CT, 21% of hepatic lesions remained unclear. In these cases, CEUS was accurate to either reveal or exclude liver metastasis in nearly all patients and could reduce costs (e.g., number of MRI scans).

Convolutional neural networks versus radiologists in characterization of small hypoattenuating hepatic nodules on CT: a critical diagnostic challenge in staging of colorectal carcinoma

Our objective was to compare the diagnostic performance and diagnostic confidence of convolutional neural networks (CNN) to radiologists in characterizing small hypoattenuating hepatic nodules (SHHN) in colorectal carcinoma (CRC) on CT scans. Retrospective review of CRC CT scans over 6-years yielded 199 patients (550 SHHN) defined as < 1 cm in diameter. The reference standard was established through 1-year stability/MRI for benign or nodule evolution for malignant nodules. Five CNNs underwent supervised training on 150 patients (412 SHHN). The remaining 49 patients (138 SHHN) were used as testing-set to compare performance of 3 radiologists to CNN, measured through ROC AUC analysis of confidence rating assigned to each nodule by the radiologists. Multivariable modeling was used to compensate for radiologist bias from visible findings other than SHHN. In characterizing SHHN as benign or malignant, the radiologists’ mean AUC ROC (0.96) was significantly higher than CNN (0.84, p = 0.0004) but equivalent to CNN adjusted through multivariable modeling for presence of synchronous ≥ 1 cm liver metastases (0.95, p = 0.9). The diagnostic confidence of radiologists and CNN were analyzed. There were significantly lower number of nodules rated with low confidence by CNN (19.6%) and CNN with liver metastatic status (18.1%) than two (38.4%, 44.2%, p < 0.0001) but not a third radiologist (11.1%, p = 0.09). We conclude that in CRC, CNN in combination with liver metastatic status equaled expert radiologists in characterizing SHHN but with better diagnostic confidence.

The value of preoperative computed tomography combined with ultrasound in the investigation of small indeterminate liver lesions in patients with colorectal cancer

Background Computed tomography (CT) is used routinely for the preoperative detection of colorectal cancer (CRC) metastases. When small indeterminate focal liver lesions are detected that are too small to characterize (TSTC) on CT, additional imaging is usually needed, resulting in a potential delay in obtaining a complete diagnostic work-up. Purpose To determine the diagnostic accuracy of ultrasound (US) of the liver performed in direct conjunction to CT in the preoperative investigation among patients with newly diagnosed CRC when indeterminate liver lesions were found on CT. Material and Methods Preoperative investigations with CT and consecutive US where CT had shown at least one focal liver lesion in 74 patients diagnosed with CRC between June 2009 and February 2012 were retrospectively reviewed. Either histopathological findings or a combination of imaging and clinical follow-up one to three years after surgery was used as the reference. Results Liver metastases were diagnosed with CT/US in 13 out of 74 patients (17.6%). In one patient, a liver cyst was preoperatively regarded as liver metastasis by a combined CT/US. The sensitivity and specificity for the CT with consecutive US procedure was 100% (13/13) and 98.4% (60/61). Conclusion US performed in conjunction with CT in patients with indeterminate focal liver lesions on CT is an accurate work-up for detection of liver metastases in patients with newly diagnosed CRC. Although our results are promising, they cannot be considered safely generalizable to all hospitals.

Contrast Enhanced Ultrasound in CT-undetermined Focal Liver Lesions

Purpose: The purpose of this study was to examine the diagnostic accuracy of CEUS in the diagnosis of focal liver lesions, which were undetermined at CT scan. Materials and Methods: From January 2010 to December 2010, patients with CT-undetermined focal liver lesions were included in this study. A total of 78 patients were evaluated: 41 men and 37 women, mean age 61.8 years; age range 30-91 years. All patients were examined with GE LOGIQ 9E ultrasound scanners with contrast-specific software, and SonoVue intravenous bolus. The standard of reference was composite consisting of: percutaneous biopsy, surgical resection, PET/CT and clinical follow-up. Results: The 78 included patients had 163 undetermined focal liver lesions, mean size 1.1 cm, range 0.1-5.3 cm. There were 18 malignant and 145 benign liver lesions, as defined by the standard of reference. In differentiating between benign vs. malignant CEUS demonstrated sensitivity, specificity, PPV, NPV and accuracy of 94.4% (95% CI: 56.3-99.5%), 99.3% (95% CI: 94.9 -99.9%), 94.4% (95% CI: 56.3-99.5%), 99.3% (95% CI: 94.9-99.9%) and 98.7% (95% CI: 94.9-99.7%), respectively. If the CEUS-inconclusive results were assumed to indicate malignancy, then sensitivity, specificity, PPV, NPV and accuracy would be 95.8% (95% CI: 66.4-99.6%), 98.6% (95% CI: 94.4-99.7%), 92.0% (95CI: 65.1-98.6%), 99.3% (95% CI: 95.0-99.9%), 98.2% (95% CI: 94.4-99.5%). Conclusion: The results of this study showed a high diagnostic accuracy for CEUS in undetermined focal liver lesions found by CT. Due to a high diagnostic accuracy of CEUS in this study, it was cautiously concluded that CEUS is useful in differentiating between malignant and benign focal liver lesions in clinical practice.

Added value of arterial enhancement fraction color maps for the characterization of small hepatic low-attenuating lesions in patients with colorectal cancer

OBJECTIVE

To assess the added value of arterial enhancement fraction (AEF) color maps for the differentiation of small metastases from hepatic benign lesions.

SUBJECTS AND METHODS

We retrospectively analyzed 46 patients with colorectal cancer who underwent multiphasic liver CT imaging and had low-attenuating liver lesions smaller than 3 cm (123 total lesions; metastasis: benign = 32:91). AEF color maps of the liver were created from multiphasic liver CT images using dedicated software. Two radiologists independently reviewed multiphasic CT image sets alone and in combination with image sets with AEF color maps using a five-point scale. The additional diagnostic value of the color maps was assessed by means of receiver-operating characteristic (ROC) analysis.

RESULTS

The area under the ROC curve (Az) increased when multiphasic CT images were combined with AEF color map analysis as compared with evaluation based only on multiphasic CT images (from 0.698 to 0.897 for reader 1, and from 0.825 to 0.945 for reader 2; P < 0.001 and 0.002, respectively). The increase Az was especially significant for lesions less than 1 cm (from 0.702 to 0.888 for reader 1, and from 0.768 to 0.958 for reader 2; P = 0.001 and P = 0.001, respectively). The mean AEF of tumor-adjacent parenchyma (35.07 ± 27.2) was significantly higher than that of tumor-free liver parenchyma (27.3 ± 20.6) (P = 0.04).

CONCLUSIONS

AEF color mapping can improve the diagnostic performance for small hepatic metastases from colorectal cancer and may allow for the elimination of additional examinations.

Prevalence and significance of subcentimeter hepatic lesions in patients with localized pancreatic adenocarcinoma

PURPOSE

To determine the prevalence and significance of incidental, subcentimeter hepatic lesions in patients with a new diagnosis of pancreatic cancer.

MATERIALS AND METHODS

This Institutional Review Board-approved retrospective study included 101 patients [45% men, median age 63 years (34-85)] treated for localized pancreatic adenocarcinoma at Brigham and Women's Hospital and Dana Farber Cancer Institute from January 1999 to December 2007. Initial staging and follow-up computed tomographic scans were reviewed to determine the frequency of liver lesions that were initially too small to characterize and later proved to be metastases. Clinical variables known to be prognostic for patients with pancreatic cancer were also recorded. Using Cox regression, we calculated adjusted hazard ratios to determine the association between presence of liver lesions and overall survival.

RESULTS

A total of 31 patients (30.7%) had subcentimeter hepatic lesions on staging scans. Of these patients, 21 (20.7% of total, 67.7% of patients with lesions) had eventual metastases to the liver. Finally, of this group, 5 patients (5.0% of total, 16.1% of patients with lesions) eventually had a metastatic focus at the specific site of the original lesion. Liver lesions predicted the occurrence of metastatic disease to the liver compared with patients without lesions (67.7% with lesions vs 44.4% without, P = .034). The presence of subcentimeter liver lesions at diagnosis was significantly associated with reduced overall survival (hazard ratio 1.65; 95% confidence interval 1.03-2.64, P = .036).

CONCLUSIONS

Subcentimeter lesions in the liver are common in patients with a new diagnosis of pancreatic cancer. Approximately 16% of these lesions represent metastases. The presence of indeterminate liver lesions may be associated with reduced overall survival.