Cholangiocarcinoma imaging: from diagnosis to response assessment

Cholangiocarcinoma (CCA), a highly aggressive primary liver cancer arising from the bile duct epithelium, represents a substantial proportion of hepatobiliary malignancies, posing formidable challenges in diagnosis and treatment. Notably, the global incidence of intrahepatic CCA has seen a rise, necessitating a critical examination of diagnostic and management strategies, especially due to presence of close imaging mimics such as hepatocellular carcinoma (HCC) and combined hepatocellular carcinoma-cholangiocarcinoma (cHCC-CCA). Hence, it is imperative to understand the role of various imaging modalities such as ultrasound, computed tomography (CT), and magnetic resonance imaging (MRI), elucidating their strengths, and limitations in diagnostic precision and staging accuracy. Beyond conventional approaches, there is emerging significance of functional imaging tools including positron emission tomography (PET)-CT and diffusion-weighted (DW)-MRI, providing pivotal insights into diagnosis, therapeutic assessment, and prognostic evaluation. This comprehensive review explores the risk factors, classification, clinical features, and role of imaging in the holistic spectrum of diagnosis, staging, management, and restaging for CCA, hence serving as a valuable resource for radiologists evaluating CCA.

Diagnostic performance and feasibility of dual-layer detector dual-energy CT for characterization of urinary stones in patients of different sizes

BACKGROUND

Urinary stones are frequently encountered in urology and are typically identified using non-contrast CT scans. Dual-energy CT (DECT) is a valuable imaging technique that produces material-specific images and allows for precise assessment of stone composition by estimating the effective atomic number (Zeff), a capability not achievable with the conventional single-energy CT's attenuation measurement method.

PURPOSE

To investigate the diagnostic performance and image quality of dual-layer detector DECT (dlDECT) in characterizing urinary stones in patients of different sizes.

METHODS

All consecutive dlDECT examinations with stone protocol and presence of urinary stones between July 2018 and November 2019 were retrospectively evaluated. Two radiologists independently reviewed 120 kVp and color-overlay Zeff images to determine stone composition (reference standard = crystallography) and image quality. The objective analysis included image noise and Zeff values measurement.

RESULTS

A total of 739 urinary stones (median size 3.7 mm, range 1-35 mm) were identified on 177 CT examinations from 155 adults (mean age, 57 ± 15 years, 80 men, median weight 82.6 kg, range 42.6-186.9 kg). Using color-overlay Zeff images, the radiologists could subjectively interpret the composition in all stones ≥ 3 mm (n = 491). For stones with available reference standards (n = 74), dlDECT yielded a sensitivity of 80% (95%CI 44-98%) and a specificity of 98% (95%CI 92-100%) in visually discriminating uric acid from non-uric acid stones. Patients weighing > 90 kg and ≤ 90 kg had similar stone characterizability (p = 0.20), with 86% of stones characterized in the > 90 kg group and 87% in the ≤ 90 kg group. All examinations throughout various patients' weights revealed acceptable image quality. A Zeff cutoff of 7.66 accurately distinguished uric acid from non-uric acid stones (AUC = 1.00). Zeff analysis revealed AUCs of 0.78 and 0.91 for differentiating calcium-based stones from other non-uric stones and all stone types, respectively.

CONCLUSION

dlDECT allowed accurate differentiation of uric acid and non-uric acid stones among patients with different body sizes with acceptable image quality.

CLINICAL IMPACT

The ability to accurately differentiate uric acid stones from non-uric acid stones using color-overlay Zeff images allows for better tailored treatment strategies, helping to choose appropriate interventions and prevent potential complications related to urinary stones in patient care.

Uncinate Duct Dilatation Predicts Additional Risk for High-Grade Dysplasia or Invasive Carcinoma Among Fukuoka-Positive Intraductal Papillary Mucinous Neoplasms

OBJECTIVE

To determine whether uncinate duct dilatation (UDD) increases the risk of high-grade dysplasia or invasive carcinoma (HGD/IC) in Fukuoka-positive intraductal papillary mucinous neoplasms (IPMNs).

BACKGROUND

Though classified as a branch duct, the uncinate duct is the primary duct of the pancreatic ventral anlage. We hypothesized that UDD, like main duct dilatation, confers additional risk for HGD/IC.

METHODS

A total of 467 patients met inclusion criteria in a retrospective cohort study of surgically resected IPMNs at the Massachusetts General Hospital. We used multivariable logistic regression to analyze the association between UDD (defined as ≥4 mm) and HGD/IC, controlling for Fukuoka risk criteria. In a secondary analysis, the modeling was repeated in the 194 patients with dorsal branch duct IPMNs (BD-IPMNs) in the pancreatic neck, body, or tail.

RESULTS

Mean age at surgery was 70, and 229 (49%) patients were female. In total, 267 (57%) patients had only worrisome features and 200 (43%) had at least 1 high-risk feature. UDD was present in 164 (35%) patients, of whom 118 (73%) had HGD/IC. On multivariable analysis, UDD increased the odds of HGD/IC by 2.8-fold, even while controlling for Fukuoka risk factors (95% CI: 1.8-4.4, P <0.001). Prevalence of HGD/IC in all patients with UDD was 73%, compared with 74% in patients with high-risk stigmata and 73% in patients with main duct IPMNs. In the secondary analysis, UDD increased the odds of HGD/IC by 3.2-fold in patients with dorsal BD-IPMNs (95% CI: 1.3-7.7, P =0.010).

CONCLUSIONS

UDD confers additional risk for HGD/IC unaccounted for by current Fukuoka criteria. Further research can extend this study to Fukuoka-negative patients, including unresected patients.