Diffusion-weighted MRI for uveal melanoma liver metastasis detection

Gadoxetic acid-enhanced MRI for the detection of liver metastases from melanoma

PURPOSE

We aimed to assess imaging findings and detection sensitivity for melanoma liver metastases on gadoxetic acid-enhanced magnetic resonance imaging (MRI).

METHODS

This retrospective study included patients with melanoma liver metastasis who underwent gadoxetic acid-enhanced MRI. Two abdominal radiologists independently evaluated signal characteristics of liver metastases on morphologic imaging (precontrast T1- and T2-weighted imaging), diffusion-weighted imaging (DWI), dynamic imaging, and hepatobiliary phase (HBP). Imaging findings were compared according to detection on HBP and the primary site of the melanoma using logistic regression with the generalized estimating equation (GEE). Detection sensitivity for metastases was compared among different MR imaging sets using logistic regression with GEE.

RESULTS

A total of 67 patients with 254 liver metastases were included (44 women; mean age ± standard deviation, 65.6 ± 13.0 years). On HBP, 76.0% of metastases were detected, and 55.5% (141/254) showed hypointensity. Most of the metastases that were not detected on HBP originated from ocular melanomas (98.4%, 60/61), ≤1 cm (90.2%, 55/61) and showed T1 hyperintensity (98.4%, 60/61). Metastases from non-ocular melanomas more frequently showed T1 hypointensity, T2 hyperintensity, diffusion restriction, arterial enhancement, and HBP hypointensity than those from ocular melanomas (Ps ≤ 0.019). The detection sensitivity of HBP (76.0%) was significantly higher than DWI (65.7%, P = 0.006), but lower than morphologic imaging (98.8%, P < 0.001) and dynamic imaging (97.6%, P < 0.001).

CONCLUSION

The detection sensitivity of HBP for melanoma liver metastasis was 76.0%, which was lower than that of morphologic or dynamic imaging. HBP of gadoxetic acid-enhanced MRI has little advantage in detecting melanoma liver metastases.

CT, MRI and PET/CT features of abdominal manifestations of cutaneous melanoma: a review of current concepts in the era of tumor-specific therapies

Abdominal manifestations in patients with cutaneous melanoma include involvement due to metastatic spread and immune checkpoint inhibitor induced adverse events. The purpose of this review is to provide a critical overview of abdominal manifestations in patients with cutaneous melanoma and highlight the current imaging challenges in the era of tumor-specific therapies. Immune checkpoint inhibitors represent a treatment with demonstrated efficacy in the treatment of advanced cutaneous melanoma but are associated with several abdominal adverse events that must be recognized. CT has a role in the identification of colitis, enteritis and pancreatitis, whereas MRI has an important role in the diagnosis of autoimmune pancreatitis. Current evidence demonstrates that MRI should be the preferred imaging technique for the detection and characterization of hepatic and splenic metastases from cutaneous melanoma. The role of ¹⁸F-FDG-PET/CT should be further evaluated but current literature suggests an efficacy in the detection of pancreatic metastases not seen on CT and MRI.

CD8 Positive T Lymphocyte Infiltration of Liver Metastases of Uveal Melanoma: A Case Report

A 78-year-old Japanese man was referred for examination of multiple small nodules on his liver detected by magnetic resonance imaging (MRI). These small nodules were hyperintense on T1-weighted MRI, and were in hepatobiliary phase on gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid enhanced MRI. Five years earlier, he had undergone curative enucleation of his left eye for uveal melanoma. US-guided biopsy revealed that the liver nodules were metastases of melanoma. Pathological examination also showed infiltration of CD8 positive T lymphocytes. The metastatic nodules remained unchanged for more than 2 years and he was not further treated. This pathology and clinical course suggest that the systemic immune response of the host could suppress hepatic metastases of uveal melanoma.

Melanoma liver metastases with special imaging features on magnetic resonance imaging after microwave ablations: How to evaluate technical efficacy?

Purpose

To evaluate the technical feasibility of microwave ablation (MWA) for melanoma liver metastases with persistent high signal on magnetic resonance imaging (MRI).

Materials and Methods

Seven patients with 22 target melanoma liver metastases who underwent MWA treatment were included. All procedure-related complications were observed and recorded. One month after MWA, the imaging features of treated liver metastases and ablation zones with different MRI sequences were reviewed to evaluate technique efficacy. To verify the correctness of the evaluation, MRI scans during patient follow-up were reviewed and compared with images before MWA to analyze changes in treated liver metastases and ablation zones.

Results

All ablations were performed successfully, and there were no procedure-related major complications. After ablation, according to MRI T1-weighted pre-contrast or contrast sequences, the persistence of high signals from the treated lesions was noted inside the ablation zones of 19 lesions. Among these 19 lesions, 17 were completely covered by the ablation zones and were considered successfully treated, whereas two lesions were not completely covered and were considered unsuccessfully treated. Three lesions could not be detected on any MRI sequence after ablation and were also considered successfully treated. Finally, MRI scans during patient follow-up care verified these evaluations.

Conclusion

MWA is a technically feasible option for melanoma liver metastases with special imaging features on MRI.

Development of a Prognostic Nomogram for Liver Metastasis of Uveal Melanoma Patients Selected by Liver MRI

Patients with liver metastases of uveal melanoma (LMUM) die from their metastatic evolution within 2 years. We established a nomogram to choose a treatment adapted to life expectancy. From 2002 to 2013, we reviewed 224 patients with LMUM selected by liver MRI. A nomogram was developed based on a Cox model. The predictive performance of the model was assessed according to the C-statistic, Kaplan–Meier curve, and calibration plots. The median follow-up was 49.2 months (range, 0.6–70.9). The survival rates at 6, 12, and 24 months were 0.88 (0.95 CI [0.84–0.93]), 0.68 (0.95 CI [0.62–0.75]), and 0.26 (0.95 CI [0.21–0.33]), respectively. The four factors selected for the nomogram with a worse prognosis were: A disease-free interval between the UM and LMUM groups of less than 6 months (HR = 3.39; 0.95 CI [1.90–6.05]), more than 10 LMUM (HR = 3.95; 0.95 CI [1.97–4.43]), a maximum LMUM of more than 1200 mm2 (HR = 2.47; 0.95 CI [1.53–3.98]), and a lactate dehydrogenase (LDH) value greater than 1.5 (HR = 3.72; 0.95 CI [2.30–6.00]). The model achieved relatively good discrimination and calibration (C-statistic 0.71). This nomogram could be useful for decision-making and risk stratification for therapeutic options.

[Importance of diffusion imaging in liver metastases]

CLINICAL/METHODICAL ISSUE

Detection and characterization of focal liver lesions.

STANDARD RADIOLOGICAL METHODS

Due to its excellent soft tissue contrast, the availability of liver-specific contrast agents and the possibility of functional imaging, magnetic resonance imaging (MRI) is the method of choice for the evaluation of focal liver lesions.

METHODICAL INNOVATIONS

Diffusion-weighted imaging (DWI) enables generation of functional information about the microstructure of a tissue besides morphological information.

PERFORMANCE

In the detection of focal liver lesions DWI shows a better detection rate compared to T2w sequences and a slightly poorer detection rate compared to dynamic T1w sequences. In principle, using DWI it is possible to distinguish malignant from benign liver lesions and also to detect a therapy response at an early stage.

ACHIEVEMENTS

For both detection and characterization of focal liver lesions, DWI represents a promising alternative to the morphological sequences; however, a more detailed characterization with the use of further sequences should be carried out particularly for the characterization of solid benign lesions. For the assessment and prognosis of therapy response, DWI offers advantages compared to morphological sequences.

PRACTICAL RECOMMENDATIONS

For the detection of focal liver lesions DWI is in principle sufficient. After visual detection of a solid liver lesion a more detailed characterization should be carried out using further sequences (in particular dynamic T1w sequences). The DWI procedure should be used for the assessment and prognosis of a therapy response.

Dual-energy CT of liver metastases in patients with uveal melanoma

Objective

To investigate the value of different kVp images of dual-energy CT (DECT) for the detection of liver metastases.

Methods

20 Patients with uveal melanoma were investigated with DECT of the liver. In each patient contrast-enhanced DECT imaging with arterial delay was performed. Number and size of metastases were documented on arterial phase 80-kVp images, virtual 120-kVp images and following angiographic images (DSA) as part of hepatic chemoperfusion. Attenuation of metastases and several anatomic regions, subjective (image noise, image quality) and objective (SNR, CNR) parameters were documented.

Results

The mean number of liver metastases detected was significant higher on 80-kVp images than on virtual 120-kVp/DSA images (5.6 ± 2.1 vs. 4.1 ± 1.8/4.3 ± 1.6); (p < 0.001). All lesions sizes were significant better detected with 80 kVp images than with virtual 120 kVp and DSA-Images (80 kVp vs. 120 kVp: <10 mm: 34 vs. 19, p < 0.05; 10–20 mm:, 33 vs. 25, p < 0.05; >20 mm: 56 vs. 42, p < 0.05/80 kVp vs. DSA: <10 mm: 34 vs. 18 p < 0.05; 10–20 mm: 33 vs. 24, p < 0.05; >20 mm: 56 vs. 41, p < 0.05). Number of detected small lesions <10 mm with 120 kVp compared to DSA-images were significant higher (19 vs. 13; p < 0.05), lesions 10–20 mm and >20 mm were measured statistically equally. Noise, SNR and CNR of 80 kVp images were higher compared to 120 kVp images. Image quality of 120 kVp images was higher compared to 80 kVp images.

Conclusion

Low-kVp images of DECT datasets are more sensitive in detecting liver metastases of patients with uveal melanoma than virtual 120 kVp- and DSA images.

Imaging of gastrointestinal melanoma metastases: Correlation with surgery and histopathology of resected specimen

OBJECTIVE

To assess the appearance of gastrointestinal melanoma metastases on CT and PET/CT and evaluate the diagnostic value of CT and PET/CT compared with surgery and histopathology.

METHODS

We retrospectively included 41 consecutive patients (aged 56.1 ± 13.5 years) with gastrointestinal melanoma metastases who underwent preoperative imaging (CT: all, PET/CT: n = 24) and metastasectomy. Two blinded radiologists assessed CT and PET/CT for gastrointestinal metastases and complications. Diagnostic accuracy and differences regarding lesion detectability and complications were assessed, using surgical findings and histopathology as standard of reference.

RESULTS

Fifty-three gastrointestinal melanoma metastases (5.0 ± 3.8 cm) were confirmed by surgery and histopathology. Lesions were located in the small bowel (81.1 %), colon (15.1 %) and stomach (3.8 %), and described as infiltrating (30.2 %), polypoid (28.3 %), cavitary (24.5 %) and exoenteric (17.0 %). Fifteen patients (37 %) had gastrointestinal complications. Higher complication rates were associated with large and polypoid lesions (p ≤ .012). Diagnostic accuracy was high for CT and PET/CT (AUC ≥ .802). For reader B (less experienced), CT yielded lower diagnostic accuracy than PET/CT (p = .044).

CONCLUSION

Most gastrointestinal melanoma metastases were located in the small bowel. Large and polypoid metastases were associated with higher complication rates. PET/CT was superior for detection of gastrointestinal melanoma metastases and should be considered in patients with limited disease undergoing surgery.

KEY POINTS

• Gastrointestinal melanoma metastases (GI-MM) are rare but often cause serious gastrointestinal complications. • Early detection of GI-MM is important to prevent complications and guide surgery. • PET/CT is superior to CT for detection of GI-MMs. • PET/CT should be considered for patients with limited disease before surgical resection.

Prospective study of surveillance testing for metastasis in 100 high-risk uveal melanoma patients

Despite advances in the local treatment of UM, half of patients develop metastases typically to the liver with poor survival. Microscopic complete surgical resection (R0) of liver metastases improves survival in high selected patients. Early identification of high-risk patients might allow detection of asymptomatic metastases, and increase R0 liver surgery rate. From October 2006 to December 2009, we conducted a prospective study to detect early minimal lesions with 6-monthly liver function tests (LFTs) and liver MRI in 100 high-risk patients. High risk was defined by primary tumor clinical or genomic criteria: thickness>8mm or diameter>15 mm, or extra-scleral extension, or monosomy 3 by FISH or aCGH. With a median follow-up of 49 months, the 5-year metastasis-free survival and overall survival were 47 and 33%, respectively. Of the 60 patients who became metastatic, 50 (83%) had exclusive liver metastasis. LFTs screening had no sufficient accurary, but biannual MRI showed high predictive value to detect metastasis and select patients eligible for curative surgery: 25/50 underwent laparotomy and among them, 8/25 (32%) had a R0 surgery. Median survival after metastasis was 14 months, mean survival reached 40 months in the R0 resected population. Six-monthly liver MRI screening is recommended in patients with large tumors or genomic high risk in order to detect early patient candidates to complete resection of liver metastases.