LIVER CT IMAGING
Variability of quantitative measurements of metastatic liver lesions: a multi-radiation-dose-level and multi-reader comparison
Ding Y, Marin D, Vernuccio F, Gonzalez F, Williamson H V., Becker H-C, et al. Variability of quantitative measurements of metastatic liver lesions: a multi-radiation-dose-level and multi-reader comparison. Abdom Radiol [Internet]. 2020 Jun 10 [cited 2020 Jun 17];1–11.
Keywords: CT, radiation dose, image quality, metastases to the liver, staging
Clinical question: If CT scans are done with low radiation doses to avoid excessive radiation to patients who already have cancer, does this reduce the quality of the staging examination and possibly prevent accurate interpretation?
What was done: The variability of tumor measurements due to radiation dose variability and interobserver (manual versus semi-automatic) variability was studied in staging examinations from 23 patients (39 metastatic liver lesions).
How was it done: All patients underwent staging CT using dual-source, single-energy, contrast-enhanced CT. The CT images were reconstructed with seven different radiation dose levels, evaluated by four radiologists manually, and evaluated by two radiologists semi-automatically.
Findings and results: Tumor size was overestimated when evaluated manually as compared with semi-automatically. Among those evaluated semi-automatically, tumors were overmeasured in images reconstructed at radiation doses <50% of the original dose. The overall variability in measurement related with radiation dose was not significantly different from inter/intraobserver variability.
Conclusion: Reducing the radiation dose level <50% of that of conventional CT protocol can detriment the quality of the staging examination.
Implications: Institutions that follow protocols to reduce radiation dose level for staging examinations of cancer may end up with overestimated size of any metastatic lesions in the liver.
Double Low-Dose Dual-Energy Liver CT in Patients at High-Risk of HCC: A Prospective, Randomized, Single-Center Study
Yoon JH, Chang W, Lee ES, Lee SM, Lee JM. Double Low-Dose Dual-Energy Liver CT in Patients at High-Risk of HCC. Invest Radiol [Internet]. 2020 Jun 1 [cited 2020 Jun 17];55(6):340–8. Available from: http://journals.lww.com/10.1097/RLI.0000000000000643
Keywords: CT, radiation dose, image quality, contrast-to-noise ratio, HCC
Clinical question: Increased image contrast improves image quality, but increased noise hinders other aspects of image quality. While decreased radiation dose (lowering the kiloelectronvolt, keV) is known to increase the contrast-to-noise ratio, it is known to increase noise overall in patients with high body-mass index (BMI). Among patients at high-risk for hepatocellular carcinoma (HCC), will double low-dose CT (decreased radiation dose, decreased intravenous contrast medium dose) affect clinical evaluation for patients at high-risk for HCC?
What was done: Low BMI patients at high risk for HCC underwent CT with standard dose versus double low-dose CT. The CT images were compared for qualitative and quantitative image noise and contrast, as well as lesion conspicuity and lesion detection.
How was it done: In this double-blinded study, 67 patients with low BMI at high risk for HCC were split into two groups: one group underwent standard-dose imaging followed by hybrid iterative reconstruction of the CT images (iDose) and the second group underwent reduced radiation dose (50 keV) and reduced contrast.
Findings and results: Lesion conspicuity was significantly higher in the double low-dose group than in the iDose group, but there was no significant difference in lesion detection. While there was no significant difference in image noise quantitatively between the two groups, there was increased contrast-to-noise ratio in the double low-dose group.
Conclusion: Double low-dose CT will not significantly change lesion detection or image noise in low BMI patients at high risk for HCC, and in fact will increase lesion conspicuity and contrast-to-noise ratio.
Implications: Patients with low BMI can be considered for double low-dose CT surveillance scans for HCC because they are inherently not as subject to increased noise in the setting of decreased radiation dose.
LIVER US IMAGING
Diagnostic value of contrast-enhanced ultrasound versus computed tomography for hepatocellular carcinoma: a retrospective, single-center evaluation of 234 patients
Schwarze V, Marschner C, Völckers W, Grosu S, Negrão de Figueiredo G, Rübenthaler J, et al. Diagnostic value of contrast-enhanced ultrasound versus computed tomography for hepatocellular carcinoma: a retrospective, single-center evaluation of 234 patients. J Int Med Res [Internet]. 2020 Jun 12 [cited 2020 Jun 17];48(6):030006052093015.
Keywords: CT, CEUS, diagnostic value, HCC
Clinical question: HCC workup is based on the imaging findings from multiple imaging modalities, among which contrast-enhanced ultrasound (CEUS) allows for dynamic assessment of liver lesion perfusion. How does the diagnostic value of contrast-enhanced ultrasound (CEUS) compare with CT for HCC in the liver?
What was done and how: 234 patients with suspicious liver lesions evaluated over a 15-year period underwent both CEUS and CT, which were then evaluated for comparative diagnostic value of HCC.
Findings and results: Results showed that CEUS had a sensitivity of 94%, specificity of 70%, PPV of 93%, and NPV of 72% for HCC, when using CT as the diagnostic gold standard.
Conclusion: The authors concluded that CEUS is safe and has high diagnostic accuracy in assessing HCC.
Implications: If an institution has capabilities to do CEUS, and would like to have additional information regarding the perfusion of the liver lesion, they can be assured that CEUS has high diagnostic accuracy for assessing HCC.
Novel Method for Ultrasound‐Derived Fat Fraction Using an Integrated Phantom
Labyed Y, Milkowski A. Novel Method for Ultrasound‐Derived Fat Fraction Using an Integrated Phantom. J Ultrasound Med [Internet]. 2020 Jun 11 [cited 2020 Jun 17];jum.15364. https://onlinelibrary.wiley.com/doi/abs/10.1002/jum.15364
Keywords: ultrasound, NAFLD, quantitative imaging biomarker, diagnostic value
Clinical question: Non-alcoholic fatty liver disease (NAFLD) can be diagnosed with histopathology from liver biopsy or by quantitative imaging such as the calculatable proton density fat fraction (PDFF) on MRI. Can an integrated reference phantom method for quantitative ultrasound be used to produce an analogous ultrasound-derived fat fraction (UDFF) tool?
What was done: Patients with known/suspected NAFLD underwent either MRI-PDFF with ultrasound or liver biopsy in order to build correlations and algorithmically produce this UDFF tool. This UDFF tool was then compared with liver biopsy results and with the MRI-PDFF.
How was it done: 101 adults with known/suspected NAFLD underwent MRI-PDFF and ultrasound scans, compared with 90 NAFLD adults who underwent liver biopsy. Linear least-squares analysis was done based on attenuation and backscatter coefficients to create the UDFF.
Findings and results: The UDFF was found to perform nearly equivalent to MRI-PDFF for the detection of lower grade NAFLD. It was found to perform high, but not as high as MRI-PDFF, for the detection of higher grade NAFLD.
Conclusion: A UDFF tool could provide a low-cost and noninvasive method for quantifying the hepatic fat fraction because the UDFF correlated well with histologic biopsy or MRI-PDFF.
Implications: The diagnosis of NAFLD can be made with liver biopsy, which is invasive, or with noninvasive quantitative imaging. While MRI can be used with its PDFF tool to calculate fat fraction, an analogous ultrasound-based UDFF tool may provide similar diagnostic value.
Characterization of Indeterminate Liver Lesions on CT and MRI With Contrast-Enhanced Ultrasound: What Is the Evidence?
Wang DC, Jang H-J, Kim TK. Characterization of Indeterminate Liver Lesions on CT and MRI With Contrast-Enhanced Ultrasound: What Is the Evidence? Am J Roentgenol [Internet]. 2020 Jun 1 [cited 2020 Jun 17];214(6):1295–304.
Keywords: CEUS, diagnostic value
Clinical question: Using CEUS, radiologists can visualize patterns of enhancement in real-time. Can CEUS therefore be used as a next-step for assessment of hepatic lesions that are indeterminate on CT or MRI?
What was done: Wang et al provide imaging examples of when CEUS has detected arterial phase enhancement or recurrence of HCC post-ablation. They additionally provide examples of how CEUS can differentiate between HCC and intrahepatic cholangiocarcinoma, benign and malignant tumor thrombi, benign and neoplastic cystic lesions, or adenoma and FNH.
Implications: CEUS can help as a next-step in the assessment of hepatic lesions that are indeterminate on CT or MRI, such as in the above-mentioned situations.
LIVER MR IMAGING
Evaluation of Glypican-3 Expression in Hepatocellular Carcinoma by Using IDEAL IQ Magnetic Resonance Imaging
Chen R, Bai Y, Liu T, et al. Evaluation of Glypican-3 Expression in Hepatocellular Carcinoma by Using IDEAL IQ Magnetic Resonance Imaging. Acad Radiol [Internet]. Elsevier; 2020 [cited 2020]
Keywords: MRI, quantitative imaging biomarker, HCC
Clinical question: Glypican-3 (GPC3) is a biomarker that can serve as a prognostic marker as well as an immunotherapeutic target for HCC. GPC3 is normally monitored from liver biopsy samples. AFP is another well-known prognostic marker for HCC derived from blood serum. Can MRI predict GPC3 expression in HCC noninvasively using imaging features alone?
What was done: 76 patients diagnosed with HCC based on histopathology underwent MRI with contrast enhancement and with an algorithm called iterative decomposition of water and fat with echo asymmetry and least squares estimation (IDEAL IQ) to evaluate for any possible quantitative imaging markers that could correlate with GPC3.
How was it done: Region of interest (ROI) was drawn on each patient’s tumor on different sequences including the IDEAL IQ fat fraction map and the R2* relaxometry. Then a Mann-Whitney U test was used to compare the corresponding intensity values within the ROI on each sequence. ROC analysis was performed.
Findings and results: MRI intensity values for the tumor on the R2* relaxometry sequence correlated with GPC3 expression, with sensitivity 85.96%, specificity 84.21%.
Conclusion: R2* values, under the use of IDEAL IQ, are reliably predictive of GPC3 expression prior to tissue sampling or surgery.
Implications: Though the underlying biophysiological mechanism for R2* correlation with GPC3 expression is unknown, this raises the possibility of noninvasively monitoring this biomarker quantitatively.
Multiphase Liver MRI for Identifying the Macrotrabecular-Massive Subtype of Hepatocellular Carcinoma
Mulé S, Galletto Pregliasco A, Tenenhaus A, Kharrat R, Amaddeo G, Baranes L, et al. Multiphase Liver MRI for Identifying the Macrotrabecular-Massive Subtype of Hepatocellular Carcinoma. Radiology. 2020 Jun 1;295(3):562–71.
Keywords: MRI, macrotrabecular-massive, HCC, imaging biomarker
Clinical question: An aggressive histological subtype of HCC called “macrotrabecular-massive” (MTM) is associated with poor survival. Can this be diagnosed with less invasive methods than tissue sampling, including MRI?
What was done: 152 patients with HCC and surgical specimens available were evaluated with MRI for features that were associated with the MTM subtype of HCC.
How was it done: Using multivariable logistic regression analyses, they identified substantial necrosis on imaging, high serum AFP level (>100 ng/mL), and Barcelona Clinic Liver Cancer (BCLC) stage B/C as independent features associated with the MTM subtype of HCC.
Findings and results: Substantial necrosis, in particular, had an odds ratio of 32, 65% sensitivity and 93% specificity for the MTM subtype. High serum AFP and BCLC stage B/C had odds ratios between 4 and 5 for the MTM subtype.
Conclusion: Substantial necrosis, high serum AFP (>100 ng/mL), and BCLC stage B/C are independent predictors for the MTM subtype of HCC. Meanwhile, early and overall tumor recurrence was most closely associated with the presence of satellite nodules.
Implications: Substantial necrosis on MRI is a noninvasive method for identifying the aggressive MTM subtype of HCC, however the prognostic value of this is yet to be determined.
LIVER VASCULAR PATHOLOGIES AND INTERVENTIONAL IMAGING
Complications after Liver Transplant Related to Preexisting Conditions: Diagnosis, Treatment, and Prevention
Horrow MM, Huynh M-HL, Callaghan MM, Rodgers SK. Complications after Liver Transplant Related to Preexisting Conditions: Diagnosis, Treatment, and Prevention. RadioGraphics [Internet]. 2020 May 1 [cited 2020 Jun 17];40(3):895–909.
Keywords: hepatic vasculature, hepatic transplant
Clinical question: Preoperative transplant imaging is done with CT or MRI. Meanwhile, post-transplant imaging is classically done with sonography as the screening modality for complications of the surgical hepatic vascular and biliary anastomoses. Which post-transplant issues are missed due to the use of sonography as opposed to CT or MRI, and why?
What was done: Horrow et al provide imaging examples of conditions that are not seen on sonography, but can arise from a variety of pre-existent vascular conditions such as prior transarterial embolization of HCC, atherosclerotic narrowing of large arteries, hepatic arterial variant anatomy, portal venous insufficiency/thrombosis, or large intra-abdominal variceal shunt and steal phenomena.
Implications: Post-transplant complications related with a variety of possible pre-existent conditions are best prevented by early recognition on preoperative CT or MRI imaging because they may not be caught on post-transplant sonography.
Transarterial chemoembolization for pulmonary or mediastinal metastases from hepatocellular carcinoma
Hori A, Ohira R, Nakamura T, Kimura Y, Ueda S, Torii M, et al. Transarterial chemoembolization for pulmonary or mediastinal metastases from hepatocellular carcinoma. Br J Radiol [Internet]. 2020 Jun 1 [cited 2020 Jun 17];93(1110):20190407.
Keywords: interventional radiology, HCC metastases, TACE
Clinical question: The side-effects from systemic molecular targeted drugs on HCC metastases are frequent, while the positive effects on the metastatic lesions are limited. Transcatheter arterial chemoembolization (TACE) is a procedure done locally for treatment of focal HCC. Can TACE be used at metastatic HCC sites in the chest for treatment to forego the need for systemic molecular targeted treatments?
What was done: 14 patients with HCC metastatic lesions in the chest were studied after TACE in combination with chemotherapy, but no molecular targeted therapy.
How was it done: Hori et al used HepaSphere for embolization, and evaluated local tumor response and adverse events as primary end points per the RECIST 1.1 criteria and CTCAE v4 criteria. Overall survival was a secondary end point.
Findings and results: Results showed acceptable safety, no 30-day mortality, 7.1% response and 100% disease control rate within the first month. Mean tumor size reduction occurred at a rate of 15.6+/-9.5% within the first month. Medial overall survival time was 15 months, with survival rates at 1 year of 57.1%, at 3 years of 28.6%, and at 5 years of 19.1%.
Conclusion: TACE with HCC is safe and effective for pulmonary and mediastinal metastases.
Implications: In patients with metastatic HCC isolated to the chest, they may be able to avoid molecular targeted therapy with its many side effects, and opt for TACE with chemotherapy. However, the feasibility of TACE is likely limited by the location of the metastatic lesions and proximity to catheterizable vessels.
Hepatic Vascular Malformation Mimics PSMA-Positive Prostate Cancer Metastasis
Hoberück S, Driesnack S, Seppelt D, Michler E, Hölscher T, Kotzerke J. Hepatic Vascular Malformation Mimics PSMA-Positive Prostate Cancer Metastasis. Clin Nucl Med [Internet]. 2020 Jun 1 [cited 2020 Jun 17];45(6):e283–4. http://journals.lww.com/10.1097/RLU.0000000000003032
Keywords: metastases to the liver, nuclear medicine, PET, cancer mimics
What was done: Patient with prostate cancer underwent PET/CT with the 68Ga-PSMA radiopharmaceutical, which uses the prostate specific membrane antigen (PSMA) to target prostate cancer and metastatic lesions.
Findings and results: The patient’s PET/CT showed PSMA-avid primary cancer, a solitary osseous vertebral metastatic lesion, and a suspicious PSMA-avid lesion in the liver, which was concerning for liver metastasis. However, based on prior contrast-enhanced CT, contrast-enhanced US, and follow-up PSMA PET/CT after androgen deprivation, the intrahepatic lesion was diagnosed as a vascular malformation that metabolically mimicked hepatic metastasis of prostate cancer.
Implications: Hepatic vascular malformations may retain radiopharmaceuticals such as 68Ga-PSMA, and possibly others, and present as false positive lesions on staging PET/CT scans.