Liver in Advance, US, CT, and MRI Moving toward the Future

ABSTRACT

Over the past two decades, the epidemiology of chronic liver disease has changed with an increase in the prevalence of nonalcoholic fatty liver disease in parallel to the advent of curative treatments for hepatitis C. Recent developments provided new tools for diagnosis and monitoring of liver diseases based on ultrasound (US), computed tomography (CT), and magnetic resonance imaging (MRI), as applied for assessing steatosis, fibrosis, and focal lesions. This narrative review aims to discuss the emerging approaches for qualitative and quantitative liver imaging, focusing on those expected to become adopted in clinical practice in the next 5 to 10 years. While radiomics is an emerging tool for many of these applications, dedicated techniques have been investigated for US (controlled attenuation parameter, backscatter coefficient, elastography methods such as point shear wave elastography [pSWE] and transient elastography [TE], novel Doppler techniques, and three-dimensional contrast-enhanced ultrasound [3D-CEUS]), CT (dual-energy, spectral photon counting, extracellular volume fraction, perfusion, and surface nodularity), and MRI (proton density fat fraction [PDFF], elastography [MRE], contrast enhancement index, relative enhancement, T1 mapping on the hepatobiliary phase, perfusion). Concurrently, the advent of abbreviated MRI protocols will help fulfill an increasing number of examination requests in an era of healthcare resource constraints.

Key points

• Technical advances in liver imaging have been observed for ultrasound, computed tomography, and magnetic resonance imaging (MRI).

• Quantitative liver imaging biomarkers are promising to measure disease severity and reduce interoperator variability.

• Quantitative liver imaging biomarkers have the potential to be increasingly adopted in clinical practice.

• Abbreviated MRI protocols will help fulfill an increasing number of examination requests.

TI-RADS helps classify thyroid lesions on ultrasound

By Amerigo Allegretto, AuntMinnie.com staff writer

May 3, 2022

Researchers in three separate but related presentations discussed existing and new research that shows the effectiveness of TI-RADS in thyroid imaging with ultrasound.

"It provides descriptive features that are associated with increased rates of malignancy," said Dr. Michelle Melany from Cedars-Sinai Medical Center in Los Angeles in her keynote speech. "It helps categorize nodules and increases the number of reports with unambiguous management recommendations."

The American College of Radiology (ACR) in 2017 developed a standardized TI-RADS risk-stratification system to inform practitioners about which thyroid nodules require biopsy. This was in response to costly interventions for nodules that turned out to be benign on biopsy.

TI-RADS uses a scoring scale that goes from 0 to 5. A score of 0 indicates a benign lesion, while 5 represents a highly suspicious finding.

Benefits of TI-RADS include having higher sensitivity than risk stratification systems, ensuring all nodules can be classified, and reducing unnecessary biopsies, among others.

However, in her ARRS 2022 talk, Melany also listed some challenges the system faces. These include having a higher interobserver variability, varying appearances, and dependence on scanning parameters.

"In most of our practices, we're super busy. If only the ultrasound technician scans, then we're really dependent on what's captured and recorded on still images or cinematic clips," Melany said.

In an abstract presentation following Melany's keynote address, Dr. Logan Haug from the Mayo Clinic in Arizona showed research he co-led assessing whether adjusting TI-RADS could further reduce including benign nodules while keeping all malignant nodules. The current TI-RADS assign a score of two points for any lobulation found on ultrasound.

The team retrospectively looked at all ultrasound and pathology records to identify 516 thyroid nodules that underwent fine-needle aspiration (FNA) and had 58 lobulated margins in a two-year period. Images were divided into two groups showing "only macrolobulated" or "microlobulations present." Microlobulations were defined as being less than 2.5 mm in circumference.

Out of the lobulated margins, 14 were found to be malignant. A total of 37 lobulated margins were solely macrolobulated (two malignant), while 21 were microlobulated (12 malignant) (p < 0.0001).

Of nodules greater than or equal to 10 mm, 53 were lobulated, including 10 malignancies. The researchers found that under current TI-RADS standards, all 53 nodules met the criteria for FNA. However, under the team's microlobulation TI-RADS standards, 38 met the criteria for FNA.

In a second abstract presentation, Dr. Meredith Bara from the University of Alberta in Canada talked about research she co-led that looked at interreader agreement after teaching sessions for residents.

The study authors used 50 test nodules scored independently by three radiology residents with no formal TI-RADS training. Bara said the residents underwent a one-hour teaching session after initial scoring, which included reviewing sonographic features of nodules and 30 training cases.

The team found that the residents showed "significant" improvement in agreement after training, with a pooled specificity between 76.6% and 96.8%. They showed the strongest agreement on nodular shape and composition.

Melany in her keynote listed some potential future modifications to TI-RADS that could further improve its effects. These include using active surveillance, changing points for certain features, incorporating nodule location, using artificial intelligence, and using newer ultrasonic methods such as contrast-enhanced ultrasound and elastography.