Small Hypoattenuating Hepatic Lesions at Contrast-enhanced CT: Prognostic Importance in Patients with Breast Cancer

Can optimized model-based iterative reconstruction improve the contrast of liver lesions in CT?

BACKGROUND

Computed tomography is a standard imaging procedure for the detection of liver lesions, such as metastases, which can often be small and poorly contrasted, and therefore hard to detect. Advances in image reconstruction have shown promise in reducing image noise and improving low-contrast detectability.

PURPOSE

To examine a novel, specialized, model-based iterative reconstruction (MBIR) technique for improved low-contrast liver lesion detection.

MATERIAL AND METHODS

Patient images with reported poorly contrasted focal liver lesions were retrospectively reconstructed with the low-contrast attenuating algorithm (FIRST-LCD) from primary raw data. Liver-to-lesion contrast, signal-to-noise, and contrast-to-noise ratios for background and liver noise for each lesion were compared for all three FIRST-LCD presets with the established hybrid iterative reconstruction method (AIDR-3D). An additional visual conspicuity score was given by two experienced radiologists for each lesion.

RESULTS

A total of 82 lesions in 57 examinations were included in the analysis. All three FIRST-LCD algorithms provided statistically significant increases in liver-to-lesion contrast, with FIRST_MILD showing the largest increase (40.47 HU in AIDR-3D; 45.84 HU in FIRST_MILD; P < 0.001). Substantial improvement was shown in contrast-to-noise metrics. Visual analysis of the lesions shows decreased lesion visibility with all FIRST methods in comparison to AIDR-3D, with FIRST_STR showing the closest results (P < 0.001).

CONCLUSION

Objective image metrics show promise for MBIR methods in improving the detectability of low-contrast liver lesions; however, subjective image quality may be perceived as inferior. Further improvements are necessary to enhance image quality and lesion detection.

Recommendations for the Management of Incidental Hepatobiliary Findings in Adults: Endorsement and Adaptation of the 2017 and 2013 ACR Incidental Findings Committee White Papers by the Canadian Association of Radiologists Incidental Findings Working Group

The Canadian Association of Radiologists Incidental Findings Working Group consists of both academic subspecialty and general radiologists and is tasked with adapting and expanding upon the American College of Radiology incidental findings white papers to more closely apply to Canadian practice patterns, particularly more comprehensively dealing with the role of ultrasound and pursuing more cost-effective approaches to the workup of incidental findings without compromising patient care. Presented here are the 2020 Canadian guidelines for the management of hepatobiliary incidental findings. Topics covered include initial assessment of hepatic steatosis and cirrhosis, the workup of incidental liver masses identified on ultrasound and computed tomography (with algorithms presented), incidental gallbladder findings (wall thickening, calcification, and polyps), and management of incidental biliary dilatation.

Characterizing indeterminate liver lesions in patients with localized pancreatic cancer at the time of diagnosis

BACKGROUND

In patients with newly diagnosed pancreatic cancer, the classification of indeterminate liver lesions is an unanswered clinical dilemma as misclassification of these lesions can impact the assignment of clinical stage and subsequent treatment planning. Our objective was to design a standardized classification system to more accurately define the risk of malignancy in indeterminate liver lesions.

METHODS

In this retrospective study, patients with localized, non-metastatic pancreatic cancer were identified and pre-treatment computed tomography (CT) scans were evaluated for the presence or absence of liver lesions. Liver lesions were defined as definitely benign (1) or indeterminate (2). Indeterminate lesions were further sub-classified as either indeterminate probably benign (2B) or indeterminate possibly malignant (2M). The index liver lesion was evaluated on follow-up imaging for stability or unequivocal disease progression.

RESULTS

From 2008 to 2015, 304 patients with localized, non-metastatic pancreatic cancer were identified and 125 (41%) patients had liver lesions. Of the 125 patients, the liver lesions in 35 (28%) were classified as definitely benign and in 90 (72%) patients they were classified as indeterminate. The 90 patients with indeterminate lesions included 80 (89%) classified as indeterminate probably benign (2B) and 10 (11%) classified as indeterminate possibly malignant (2M). After a median follow-up of 56 weeks, no patient with a definitely benign lesion had metastatic disease progression of the index lesion. Of the 90 patients with indeterminate liver lesions, the index lesion progressed to unequivocal liver metastasis in 8 (9%) patients; 5 (6%) of the 80 lesions classified as indeterminate probably benign (2B), and 3 (30%) of the ten lesions classified as indeterminate possibly malignant (2M). The sensitivity of the classification system was 38% and the specificity was 91%. The positive predictive value was 30% and the negative predictive value was 94%.

CONCLUSIONS

A significant proportion of patients with localized pancreatic cancer will have liver lesions identified at the time of diagnosis and most of these lesions will have indeterminate characteristics. A classification system which further stratifies indeterminate liver lesions by malignant potential can assist clinicians in determining optimal treatment plan and is associated with a high negative predictive value.

That liver lesion on MDCT in the oncology patient: is it important?

Multidetector-row computed tomography (MDCT) has become the primary imaging test for the staging and follow-up of most malignancies that originate outside of the central nervous system. Technical advances in this imaging technique have led to significant improvement in the detection of metastatic disease to the liver. An unintended by-product of this improving diagnostic acumen is the discovery of incidental hepatic lesions in oncology patients that in the past remained undetected. These ubiquitous, incidentally identified hepatic lesions have created a management dilemma for both clinicians and radiologists: are these lesions benign or do they represent metastases? Naturally, the answer to this question has profound prognostic and therapeutic implications. In this review, guidelines concerning the diagnosis and management of some of the more common hepatic incidental lesions detected in patients with extrahepatic malignancies are presented.

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.

Diagnostic efficacy of gadoxetic acid-enhanced MRI for the detection and characterisation of liver metastases: comparison with multidetector-row CT

OBJECTIVES

We compared the diagnostic performance of gadoxetic acid-enhanced MRI and 16-slice multidetector CT (MDCT) with respect to their abilities to detect hepatic metastases and differentiate hepatic metastases from hepatic cysts and haemangiomas.

METHODS

67 patients with 110 liver metastases (size 0.3-2.5 cm), 33 haemangiomas (size 0.5-1.5 cm) and 17 cysts (size 0.3-1.0 cm) underwent 4-phase MDCT and gadoxetic acid-enhanced MRI, including early dynamic phases, post-contrast T(2) weighted turbo spin echo sequences and 20 min hepatocyte-selective phases. Two observers independently analysed each image in random order. Sensitivity and diagnostic accuracy for lesion detection and differentiation for MDCT and gadoxetic acid-enhanced MRI were calculated using receiver operating characteristic analysis.

RESULTS

For both observers, the Az values of gadoxetic acid-enhanced MRI (mean, 0.982 and 0.981) were significantly higher than the Az values of MDCT (mean, 0.839 and 0.892) (p<0.05) for the detection of metastases and for the differentiation of metastases from haemangiomas and cysts. Sensitivities of gadoxetic acid-enhanced MRI with regard to the detection and characterisation of liver metastases (mean, 96.9% and 96.0%) were significantly higher than those of MDCT (mean, 78.7% and 75.0%) (p<0.05).

CONCLUSION

Gadoxetic acid-enhanced MRI showed higher diagnostic accuracy and sensitivity than did MDCT for the detection of hepatic metastases and for the differentiation between hepatic metastases and hepatic haemangiomas or cysts.

Frequency and etiology of unexplained bilateral hydronephrosis in patients with breast cancer: results of a longitudinal CT study

We retrospectively reviewed the records of 153 patients with breast cancer undergoing serial abdominal computed tomography (CT). During a median follow-up of 40 months, 2 (1.4%) of 153 patients developed bilateral hydronephrosis in the absence of radiologically visible obstructing pathology. Surgery confirmed malignant infiltration of the ureters by metastatic lobular carcinoma in both patients, suggesting that new unexplained bilateral hydronephrosis on serial CT in patients with breast cancer is likely to reflect infiltrative retroperitoneal involvement of the ureters by metastatic lobular carcinoma.

Current imaging strategies of primary and secondary neoplasms of the liver

This article details the diagnosis and imaging of primary and secondary neoplasms of the liver. Benign conditions that can mimic malignancy are also discussed, such as focal nodular hyperplasia and adenoma. Considerable attention is given to hepatoma, which is the most common primary hepatic tumor in the United States. The roles of magnetic resonance imaging, computed tomography, and ultrasound are evaluated, with recommendations for their effective use. Pitfalls in imaging related to posttreatment changes and unusual patterns of metastatic disease are illustrated.

Hepatic incidentalomas

Recent advances in multidetector-row computed tomography, magnetic resonance imaging, and ultrasonography have led to the detection of incidental hepatic lesions in both the oncology and nononcology patient population that in the past remained undiscovered. These incidental hepatic lesions have created a management dilemma for both clinicians and radiologists. In this review, guidelines concerning the diagnosis and management of some of the more common hepatic incidentalomas are presented.

Diffusion-weighted MRI and liver metastases

Liver metastases are the most frequently encountered malignant liver lesions in the Western countries. Accurate diagnosis of liver metastases is essential for appropriate management of these patients. Multiple imaging modalities, including ultrasound, CT, positron emission tomography, and MRI, are available for the evaluation of patients with suspected or known liver metastases. Contrast-enhanced MRI has a high accuracy for detection and characterization of liver lesions. Additionally, diffusion-weighted MRI (DWI) has been gaining increasing attention. It is a noncontrast technique that is easy to perform, could be incorporated in routine clinical protocols, and has the potential to provide tissue characterization. This article discusses the basic principles of DWI and discusses its emerging role in the detection of liver metastases in patients with extrahepatic malignancies.

Detection of colo-rectal liver metastases: prospective comparison of contrast enhanced US, multidetector CT, PET/CT, and 1.5 Tesla MR with extracellular and reticulo-endothelial cell specific contrast agents

BACKGROUND

To compare contrast-enhanced US (CE-US), multidetector-CT (MDCT), 1.5 Tesla MR with extra-cellular (Gd-enhanced) and intracellular (SPIO-enhanced) contrast agents and PET/CT, in the detection of hepatic metastases from colorectal cancer.

MATERIALS AND METHODS

A total of 34 patients with colo-rectal adenocarcinoma underwent preoperatively CE-US, MDCT, Gd- and SPIO-enhanced MR imaging (MRI), and PET/CT. Each set of images was reviewed independently by two blinded observers. The ROC method was used to analyze the results, which were correlated with surgical findings, intraoperative US, histopathology, and MDCT follow-up.

RESULTS

A total of 57 hepatic lesions were identified: 11 hemangiomas, 29 cysts, 1 focal fatty liver, 16 metastases (dimensional distribution: 5/16 < 5 mm; 3/16 between 5 mm and <10 mm; 8/16 ≥ 10 mm). Six of 34 patients were classified as positive for the presence of at least one metastasis. Considering all the metastases and those ≥ 10 mm, ROC areas showed no significant differences between Gd- and SPIO-enhanced MRI, which performed significantly better than the other modalities (P < 0.05). Considering the lesions <10 mm, ROC areas showed no significant differences between all modalities; however MRI presented a trend to perform better than the other techniques. Considering the patients, ROC areas showed no significant differences between all the modalities; however PET/CT seemed to perform better than the others.

CONCLUSIONS

Gd- and SPIO-enhanced MRI seem to be the most accurate modality in the identification of liver metastases from colo-rectal carcinoma. PET/CT shows a trend to perform better than the other modalities in the identification of patients with liver metastases.

Role of IV iodinated contrast material in 18F-FDG PET/CT of liver metastases

OBJECTIVE

The purpose of our study was to investigate the role of IV iodinated contrast material in the evaluation of hepatic metastases at (18)F-FDG PET/CT.

MATERIALS AND METHODS

We retrospectively identified 39 patients (25 men and 14 women) with suspected isolated hepatic metastases from colorectal cancer who underwent FDG PET/CT. The CT protocol included acquisition of unenhanced and multiphase contrast-enhanced CT images through the liver. At two separate sittings, four readers (two radiologists and two nuclear medicine physicians) noted and characterized all hepatic lesions in consensus, first based on PET and unenhanced CT images and later based on PET and contrast-enhanced CT images. The nature of detected lesions was established by histopathologic or clinicoradiologic correlation.

RESULTS

A total of 178 hepatic lesions were identified, consisting of 137 metastases and 41 benign lesions. Using lesion-based analyses with Obuchowski's method for paired observations, 172 of 178 lesions (97%) were detected at PET/contrast-enhanced CT compared with only 135 of 178 (76%) at PET/unenhanced CT (p = 0.0004). Specifically, 114 of 137 (83%) hepatic metastases were detected on PET/contrast-enhanced CT compared with 92 of 137 (67%) on PET/unenhanced CT (p = 0.012). One hundred thirty-one of 178 lesions (73%) were accurately characterized at PET/contrast-enhanced CT compared with 101 of 178 (57%) at PET/unenhanced CT (p = 0.004).

CONCLUSION

IV iodinated contrast material administration improves the detection of hepatic metastases and the characterization of focal hepatic lesions at PET/CT.

Lésions hépatiques en cancérologie générale

In order to improve management of oncologic patients, a standardized 5-step approach should be considered: detection, characterization, locoregional and systemic staging, and post treatment follow up. The use of imaging techniques will be adapted to the clinical question at hand during multi-disciplinary review of cases. The role of the radiologist is to review the indications for each imaging modality and incorporate the results in the clinical context.

Detection and characterization of liver metastases: 16-slice multidetector computed tomography versus superparamagnetic iron oxide-enhanced magnetic resonance imaging

The aim of our study was to compare the diagnostic performance of 16--slice multidetector computed tomography with that of superparamagnetic iron oxide (SPIO)-enhanced magnetic resonance (MR) imaging in the detection of small hepatic metastases and in the differentiation of hepatic metastases from cysts. Twenty-three patients with 55 liver metastases and 14 liver cysts underwent SPIO-enhanced MR imaging and multiphasic CT using 16-MDCT. Two observers independently analyzed each image, in random order. Sensitivity and diagnostic accuracy for lesion detection and differentiation as metastases or cysts for MDCT and SPIO-enhanced MR imaging were calculated using receiver operating characteristic analysis. For all observers, the Az values of SPIO-enhanced MR imaging for lesion detection and differentiation of liver metastases from cysts (mean 0.955, 0.999) were higher than those of MDCT (mean 0.925, 0.982), but not statistically significantly so (P > 0.05). Sensitivity of SPIO-enhanced MR imaging with regard to the detection of liver metastases (mean 94.5%) was significantly higher than that of MDCT (mean 80.0%) (P < 0.05). SPIO-enhanced MR imaging and 16-MDCT showed similar diagnostic accuracies for detection and differentiation of liver metastases from cysts, but sensitivity of SPIO-enhanced imaging in the detection of liver metastases was superior to that of 16-MDCT.