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Simple Summary: Liver metastases presenting as small hyperintense lesions on diffusion-weighted imaging pose a therapeutic challenge for conventional thermal ablation, as they are often occult on ultrasound and CT. This study aimed to assess the efficacy of the Hepatic Arteriography and C-Arm CT-Guided Ablation (HepACAGA) technique, a novel approach that integrates C-arm CT hepatic arteriography with C-arm CT-guided navigation, for treating small liver metastases (≤10 mm) detected on MRI. A total of 15 patients with 26 liver metastases were included. The metastases originated predominantly from colorectal cancer (73%), followed by neuro-endocrine tumors (15%), breast cancer (8%) and esophageal cancer (4%). The HepACAGA technique achieved a 100% technical success rate in detecting and ablating the small metastases. After a median follow-up of 9 months, one tumor recurred (4%) which was successfully treated with a subsequent re-ablation. No complications were observed. These findings demonstrate that the HepACAGA technique can effectively ablate subcentimeter liver metastases identified on MRI. Purpose: Liver metastases presenting as small hyperintense foci on diffusion-weighted imaging (DWI) pose a therapeutic challenge. Ablation is generally not possible since these lesions are often occult on ultrasound and CT. The purpose of this prospective study was to assess if small liver metastases (≤10 mm) detected on DWI can be successfully localized and ablated with the Hepatic Arteriography and C-Arm CT-Guided Ablation technique (HepACAGA). Materials and Methods: All consecutive patients with small liver metastases (≤10 mm), as measured on DWI, referred for ablation with HepACAGA between 1 January 2021, and 31 October 2023, were included. Re-ablations and ablations concomitant with another local treatment were excluded. The primary outcome was the technical success rate, defined as the intraprocedural detection and subsequent successful ablation of small liver metastases using HepACAGA. Secondary outcomes included the primary and secondary local tumor progression (LTP) rates and the complication rate. Results: A total of 15 patients (26 tumors) were included, with liver metastases from colorectal cancer (73%), neuro-endocrine tumors (15%), breast cancer (8%) and esophageal cancer (4%). All 26 tumors were successfully identified, punctured and ablated (a technical success rate of 100%). After a median follow-up of 9 months, primary and secondary LTP were 4% and 0%, respectively. No complications occurred. Conclusion: In this proof-of-concept study, the HepACAGA technique was successfully used to detect and ablate 100% of small liver metastases identified on DWI with a low recurrence rate and no complications. This technique enables the ablation of subcentimeter liver metastases detected on MRI. [ABSTRACT FROM AUTHOR]

Simple Summary: Catheter-assisted ablations have shown significant improvements in the outcomes of percutaneous thermal ablation for liver cancer. A novel approach within this category is the Hepatic Arteriography and C-Arm CT-Guided Ablation (HepACAGA) technique, which integrates C-arm CT hepatic arteriography with C-arm guided navigation. This cohort study aimed to assess the effectiveness and safety of the HepACAGA technique compared to conventional ultrasound/CT-guided thermal ablation in treating hepatocellular carcinoma and colorectal liver metastasis. A total of 68 patients with 120 tumors undergoing HepACAGA and 53 patients with 78 tumors undergoing conventional ablation were included. The HepACAGA technique demonstrated superior outcomes: lower rates of local tumor recurrence, longer local tumor recurrence-free survival, and fewer procedure-related complications. These findings suggest that HepACAGA is a safer and more effective ablation technique in liver cancer treatment compared to conventional ablation methods. Purpose: Hepatic Arteriography and C-Arm CT-Guided Ablation of liver tumors (HepACAGA) is a novel technique, combining hepatic–arterial contrast injection with C-arm CT-guided navigation. This study compared the outcomes of the HepACAGA technique with patients treated with conventional ultrasound (US) and/or CT-guided ablation. Materials and Methods: In this retrospective cohort study, all consecutive patients with hepatocellular carcinoma (HCC) or colorectal liver metastases (CRLM) treated with conventional US-/CT-guided ablation between 1 January 2015, and 31 December 2020, and patients treated with HepACAGA between 1 January 2021, and 31 October 2023, were included. The primary outcome was local tumor recurrence-free survival (LTRFS). Secondary outcomes included the local tumor recurrence (LTR) rate and complication rate. Results: 68 patients (120 tumors) were included in the HepACAGA cohort and 53 patients (78 tumors) were included in the conventional cohort. In both cohorts, HCC was the predominant tumor type (63% and 73%, respectively). In the HepACAGA cohort, all patients received microwave ablation. Radiofrequency ablation was the main ablation technique in the conventional group (78%). LTRFS was significantly longer for patients treated with the HepACAGA technique (p = 0.015). Both LTR and the complication rate were significantly lower in the HepACAGA cohort compared to the conventional cohort (LTR 5% vs. 26%, respectively; p < 0.001) (complication rate 4% vs. 15%, respectively; p = 0.041). Conclusions: In this study, the HepACAGA technique was safer and more effective than conventional ablation for HCC and CRLM, resulting in lower rates of local tumor recurrence, longer local tumor recurrence-free survival and fewer procedure-related complications. [ABSTRACT FROM AUTHOR]

Background: Recent studies have shown a clear relationship between absorbed dose and tumor response to treatment after hepatic radioembolization. These findings help to create more personalized treatment planning and dosimetry. However, crucial to this goal is the ability to predict the dose distribution prior to treatment. The microsphere distribution is ultimately determined by (i) the hepatic vasculature and the resulting blood flow dynamics and (ii) the catheter position. Purpose: To show that pretreatment, intra‐procedural imaging of blood flow patterns, as quantified by catheter‐directed intra‐arterial contrast enhancement, correlate with posttreatment microsphere accumulation and, consequently, absorbed dose. Materials and methods: Patients who participated in a clinical trial (NCT01177007) and for whom both a pretreatment dual‐phase contrast‐enhanced cone‐beam CT (CBCT) and a posttreatment 90Y PET/CT scan were available were included in this retrospective study. Tumors and perfused volumes were manually delineated on the CBCT by an experienced radiologist. The mean, sum, and standard deviation of the voxels in each volume were recorded. The delineations were transferred to the PET‐based absorbed dose maps by coregistration of the corresponding CTs. Linear multiple regression was used to correlate pretreatment CBCT enhancement to posttreatment 90Y PET/CT‐based absorbed dose in each region. Leave‐one‐out cross‐validation and Bland–Altman analyses were performed on the predicted versus measured absorbed doses. Results: Nine patients, with a total of 23 tumors were included. All presented with hepatocellular carcinoma (HCC). Visually, all patients had a clear correspondence between CBCT enhancement and absorbed dose. The correlation between CBCT enhancement and posttherapy absorbed tumor dose based was strong (R2 = 0.91), and moderate for the non‐tumor liver tissue (R2 = 0.61). Limits of agreement were approximately ±55 Gray for tumor tissue. Conclusion: There is a linear relationship between pretreatment blood dynamics in HCC tumors and posttreatment absorbed dose, which, if shown to be generalizable, allows for pretreatment tumor absorbed dose prediction. [ABSTRACT FROM AUTHOR]

Purpose: Radiation pneumonitis is a serious complication of radioembolization. In holmium-166 ([166Ho]) radioembolization, the lung mean dose (LMD) can be estimated (eLMD) using a scout dose with either technetium-99 m-macroaggregated albumin ([99mTc]MAA) or [166Ho]-microspheres. The accuracy of eLMD based on [99mTc]MAA (eLMDMAA) was compared to eLMD based on [166Ho]-scout dose (eLMDHo-scout) in two prospective clinical studies. Materials and Methods: Patients were included if they received both scout doses ([99mTc]MAA and [166Ho]-scout), had a posttreatment [166Ho]-SPECT/CT (gold standard) and were scanned on the same hybrid SPECT/CT system. The correlation between eLMDMAA/eLMDHo-scout and LMDHo-treatment was assessed by Spearman's rank correlation coefficient (r). Wilcoxon signed rank test was used to analyze paired data. Results: Thirty-seven patients with unresectable liver metastases were included. During follow-up, none developed symptoms of radiation pneumonitis. Median eLMDMAA (1.53 Gy, range 0.09–21.33 Gy) was significantly higher than median LMDHo-treatment (0.00 Gy, range 0.00–1.20 Gy; p < 0.01). Median eLMDHo-scout (median 0.00 Gy, range 0.00–1.21 Gy) was not significantly different compared to LMDHo-treatment (p > 0.05). In all cases, eLMDMAA was higher than LMDHo-treatment (p < 0.01). While a significant correlation was found between eLMDHo-scout and LMDHo-treatment (r = 0.43, p < 0.01), there was no correlation between eLMDMAA and LMDHo-treatment (r = 0.02, p = 0.90). Conclusion: [166Ho]-scout dose is superior in predicting LMD over [99mTc]MAA, in [166Ho]-radioembolization. Consequently, [166Ho]-scout may limit unnecessary patient exclusions and avoid unnecessary therapeutic activity reductions in patients eligible for radioembolization. Trail registration: NCT01031784, registered December 2009. NCT01612325, registered June 2012. [ABSTRACT FROM AUTHOR]

Background: With the introduction of prostate specific membrane antigen (PSMA) PET/CT, the detection rate of prostate cancer metastases has improved significantly, both for primary staging and for biochemical recurrence. EANM/SNMMI guidelines recommend a 60 min time interval between [68Ga]Ga‐PSMA administration and acquisition. Purpose: This study evaluates the possibility of a shorter time interval by investigating the dynamic change in image quality measures. Method: We retrospectively analyzed 10 consecutive prostate cancer patients who underwent a dynamic whole body [68Ga]Ga‐PSMA‐11 PET/CT of 75 min from skull vertex to mid‐thigh using Siemens FlowMotion. PET images were acquired directly after injection of 1.5 MBq/kg [68Ga]Ga‐PSMA‐11. Image quality measures included lesion maximum standardized uptake value corrected for lean body mass (SULmax), tumor‐to‐background ratio (TBR), and contrast‐to‐noise ratio (CNR). Quantitative analysis of image quality in dynamic PET was performed using PMOD (version 4.2). Regions of interest (ROIs), drawn included different types of prostate lesions (primary tumor, lymph nodes, and bone metastasis), organ tissue (liver, spleen, lacrimal gland, submandibular gland, parotid gland, urinary bladder, kidneys blood pool [ascending aorta], left ventricle), bone tissue (4th lumbar vertebral body [L4]) and muscle tissue (gluteus maximus). To further investigate image quality four 10 min multi‐frame reconstructions with clinical parameters were made at different post‐injection times (15, 30, 45, and 60 min). A nuclear medicine physician performed a blinded lesion detectability evaluation on these multi‐frame reconstructions for different prostate cancer lesions. Results: Six primary prostate tumors in seven patients with prostate in situ, 13 lymph node metastases in six patients and up to 12 bone metastases in three patients were found. The different prostate lesion types (lymph nodes metastases, bone metastases, and primary prostate tumor) all show an increase in average SULmax, TBR, and CNR over time during the scan. The normalized average SULmax, TBR, and CNR of the combined prostate lesions at 15, 30, and 45 min post‐injection scans were all significant p < 0.05 lower from the 60 min post‐injection [68Ga]Ga‐PSMA‐11 PET/CT (9.5 ± 4.5, 12.7 ± 6.2, and 41.8 ± 24.5, respectively). At patient level, the reader concluded the same regarding the presence/absence of primary prostate cancer recurrence, lymph node metastases, and/or bone metastases on all <60 min post‐injection [68Ga]Ga‐PSMA‐11 PET/CT's in comparison to the reference scan (60 min post‐injection). At lesion level, all bone metastases seen on the reference scan were also seen on all <60 min post‐injection [68Ga]Ga‐PSMA‐11 PET/CT's but there were some lymph nodes (n = 2) metastases missed on the 15, 30, and 45 min post‐injection scans. One lymph node metastasis on both the 15 and 30 min post‐injection [68Ga]Ga‐PSMA‐11 PET/CT's was missed and one lymph node metastasis was missed, only on the 45 min post‐injection [68Ga]Ga‐PSMA‐11 PET/CT. Conclusion: Shorter post‐injection times (15, 30, and 45 min) compared to the recommended post‐injection time of 60 min are not optimal. However, the impact of a shorter time interval of 45 min instead of 60 min between [68Ga]Ga‐PSMA‐11 administration and the start of PET/CT acquisition on both image quality (SULmax, TBR, and CNR) and lesion detection, while significant, is small. [ABSTRACT FROM AUTHOR]