Evaluation of the position of the central venous catheter tip of implantable venous access devices in the occurrence of postoperative thrombotic and non-thrombotic complications.

BACKGROUND: The position of the catheter tip of totally implantable venous access devices (TIVAD) is a risk factor for postoperative complications. The study aim was to assess the early and late complications (EC and LC) associated with the position of the catheter tip in cancer patients. METHODS: We reviewed cancer patients who had a TIVAD placed in 2020. EC (≤ 90 days), LC (> 90 days) and risk factors for TIVAD-associated complications were assessed. The vertical mismatch of the catheter tip was compared to an "ideal position" (> 10 mm below the carina and ≥ 20 mm below the right main bronchus (RMB)) using chest x-ray, post-implantation. RESULTS: 301 patients were included. Median follow-up after TIVAD implantation was 9.4 months. All TIVAD catheters were inserted via the internal jugular vein (IJV). The mean distance between the catheter tip and the carina and the RMB was 21.3 mm and 6.63 mm respectively. In total, 11.3% patients developed EC and 5.6% had LC. An association was found between the position of the catheter tip from the carina (≤ 10 mm vs. > 10 mm) and the occurrence of EC (18.3% vs. 8.6%, p = 0.01) and for the catheter insertion side (left IJV vs. right IJV) (19.1% vs. 9.0% p = 0.02). Multivariate analysis showed that left IJV catheter insertion (OR 2.76), and a catheter tip located ≤ 10 mm below the carina (OR 2.71) are significant independent risk factors of EC. CONCLUSIONS: TIVAD catheter tip located at ≤ 10 mm below the carina, and a left-side inserted catheter, are higher risk of EC.

Predictive factors of non-completion of cytoreductive surgery in colorectal peritoneal metastasis.

INTRODUCTION: Cytoreductive surgery (CRS) ± hyperthermic intraperitoneal chemotherapy (HIPEC) is the only potentially curative treatment that can improve the survival prognosis for patients with peritoneal metastasis (PM) of colorectal origin. The main independent prognostic factors are extent of disease, as measured by the Peritoneal Cancer Index (PCI), and completion of CRS (CC-0 or R1). Despite thorough preoperative work-up for selection of surgical candidates, 20%-25 % of CRS procedures are stopped after exploration during laparotomy. These patients undergo "open-and-close" procedures associated with a risk of complications and without any benefit. The aim of this study was to identify preoperative predictors of non-resectability and/or non-completion of CRS in patients with colorectal PMs who were candidates for surgery. MATERIALS AND METHODS: Retrospective, monocentric study including patients admitted for CRS ± HIPEC at the Jules Bordet Institute between January 01, 2010 and December 31, 2021. The preoperative epidemiological, pathological, clinical, radiological, and biological features of patients with unresectable disease were compared with those of patients treated with CRS. RESULTS: One hundred nineteen patients were included, 60 men and 59 women (median age 61 years). Twenty-one CRS procedures (17.65 %) were stopped during exploratory laparotomy. Statistically significant factors associated with non-completion were age (p = 0.0183), PCI (p = 0.0001), presence of sub/occlusive episode(s) prior to CRS (p = 0.0012), and multifocal-diffuse uptakes on PET-scan (p = 0.0017). CONCLUSION: Almost 18 % of patients had an "open-and-close" procedure. PCI was the major determinant of non-completion of CRS. Other predictive factors of unresectability of colorectal PM were age, the presence of sub/occlusive episodes, and PET/CT with multiple peritoneal uptakes.

Clinical impact of 99mTc-MAA SPECT/CT-based personalized predictive dosimetry in selective internal radiotherapy: a real-life single-center experience in unresectable HCC patients.

BACKGROUND: Recent data demonstrated that personalized dosimetry-based selective internal radiotherapy (SIRT) is associated with better outcome for unresectable hepatocellular carcinoma (HCC). AIM: We aim to evaluate the contribution of personalized predictive dosimetry (performed with Simplicity90® software) in our population of HCC patients by comparing them to our historical cohort whose activity was determined by standard dosimetry. METHODS: This is a retrospective, single-center study conducted between February 2016 and December 2020 that included patients with HCC who received SIRT after simulation based on either standard dosimetry (group A) or, as of December 2017, on personalized dosimetry (group B). Primary endpoints were best overall response (BOR) and objective response rate (ORR) evaluated by mRECIST at 3 months. Safety and toxicity profiles were evaluated at 1- and 3-months post-treatment. For group A we compared the activity to be administered determined a posteriori using Simplicit90Y® and the activity actually administered determined by the standard approach. RESULTS: Between February 2016 and December 2020, 66 patients received 69 simulations leading to 40 treatments. The median follow-up time was equal for both groups, 21 months (range 3-55) in group A and 21 months (range 4-39) in group B. The per patient analysis revealed a significant benefit of personalized predictive dosimetry in terms of better overall response at 3 months (80% vs. 33.3%, p = 0.007) and at 6 months (77.8% vs. 22.2%, p = 0.06). This trend was found in the analysis by nodule with a response rate according to mRECIST of 87.5% for personalized dosimetry versus 68.4% for standard dosimetry at 3 months, p = 0.24. Only one grade 3 biological toxicity (hyperbilirubinemia) was noted in group A. The comparison between the administered activity and the recommended activity recalculated a posteriori using Simplicit90Y® showed that the vast majority of patients who progressed (83.33%) received less activity than that recommended by the personalized approach or an inadequate distribution of the administered activity. CONCLUSIONS: Our study aligns to recent literature and confirms that the use of personalized dosimetry allows a better selection of HCC patients who can benefit from SIRT, and consequently, improves the effectiveness of this treatment.

Deep epigastric lymph nodes implication in patients' recurrence pattern after cytoreductive surgery in ovarian peritoneal metastases.

INTRODUCTION: Although complete cytoreductive surgery (CRS) with or without hyperthermic intraperitoneal chemotherapy (HIPEC) offers a good prognosis in patients with peritoneal metastasis of ovarian cancer (PMOC), recurrences are quite common. These recurrences can be intra-abdominal or systemic in nature. Our objective was to study and illustrate the global recurrence pattern in patients operated for PMOC, shedding light on a previously overlooked lymphatic basin at the level of the epigastric artery, the deep epigastric lymph nodes (DELN) basin. PATIENTS AND METHODS: This was a retrospective study including patients with PMOC who underwent surgery with curative-intent, from 2012 until 2018, at our cancer center, and who presented with any type of disease recurrence on follow-up. CT-scans, MRIs and PET-scans were reviewed in order to determine solid organs and lymph nodes (LN) recurrences. RESULTS: During the study period, 208 patients underwent CRS ± HIPEC, 115 (55.3%) presented with organ or lymphatic recurrence over a median follow-up of 81 months. Sixty percent of these patients had radiologically enlarged LN involvement. The pelvis/pelvic peritoneum was the most common intra-abdominal organ recurrence site (47%), while the retroperitoneal LN was the most common lymphatic recurrence site (73.9%). Previously overlooked DELN were found in 12 patients, with 17.4% implication in lymphatic basin recurrence patterns. CONCLUSION: Our study revealed the potential role of the DELN basin, previously overlooked in the systemic dissemination process of PMOC. This study sheds light on a previously unrecognized lymphatic pathway, as an intermediate checkpoint or relay, between the peritoneum, an intra-abdominal organ, and the extra-abdominal compartment.

Defining textbook outcome for selective internal radiation therapy of hepatocellular carcinoma: an international expert study.

BACKGROUND: A textbook outcome (TO) is a composite indicator covering the entire intervention process in order to reflect the "ideal" intervention and be a surrogate for patient important outcomes. Selective internal radiation therapy (SIRT) is a complex multidisciplinary and multistep intervention facing the challenge of standardization. This expert opinion-based study aimed to define a TO for SIRT of hepatocellular carcinoma. METHODS: This study involved two steps: (1) the steering committee (4 interventional radiologists) first developed an extensive list of possible relevant items reflecting an optimal SIRT intervention based on a literature review and (2) then conducted an international and multidisciplinary survey which resulted in the final TO. This survey was online, from February to July 2021, and consisted three consecutive rounds with predefined settings. Experts were identified by contacting senior authors of randomized trials, large observational studies, or studies on quality improvement in SIRT. This study was strictly academic. RESULTS: A total of 50 items were included in the first round of the survey. A total of 29/40 experts (73%) responded, including 23 interventional radiologists (79%), three nuclear medicine physicians (10%), two hepatologists, and one oncologist, from 11 countries spanning three continents. The final TO consisted 11 parameters across six domains ("pre-intervention workup," "tumor targeting and dosimetry," "intervention," "post-90Y imaging," "length of hospital stay," and "complications"). Of these, all but one were applied in the institutions of > 80% of experts. CONCLUSIONS: This multidimensional indicator is a comprehensive standardization tool, suitable for routine care, clinical round, and research.

Added Value of Computed Tomography Angiography Prior to Bronchial Artery Embolization for Hemoptysis: A Retrospective Two-Center Study.

Objectives: The aim of this retrospective study was to evaluate the added value of pre-procedural computed tomography angiography (CTA) prior to bronchial artery embolization for patients presenting with hemoptysis. Materials and Methods: In this retrospective study, we evaluated patients admitted for hemoptysis from 2010 to 2021 and treated by catheter-directed embolization. After establishing quality criteria for pre-procedural computed tomography (CT), patients were divided into two groups depending on their pre-procedural imaging assessment: Quality CT-angiography (QCTA group) and suboptimal pre-procedural imaging (suboptimal CTA, unenhanced or no CT evaluation; control group). Groups were compared based on radiological success, procedure-related complications, and clinical success, including cessation of hemoptysis, recurrence rates, and overall mortality. Results: We included 31 patients in the QCTA group, and 35 in the control group. Clinical success was n = 24/31 (77.4%) in the QCTA group and n = 27/35 (77.1%) in the control group (p = 0.979). Technical success was n = 37/42 (88.1%) in the QCTA group and n = 39/42 (92.86%) in the control group (p = 0.820). Overall recurrence was 10.6%. Minor complications occurred in 27.3%, and one major complication was reported.The concordance between the affected bleeding lung and the identification of pathological arteries during angiography was better in the QCTA group (p = 0.045).The average number of culprit arteries (bronchial, non-bronchial systemic arteries [NBSA] or pulmonary) in the QCTA group was not significantly higher than that in the control group. Conclusions: Preprocedural QCTA better identifies the affected bleeding lung and bleeding vessels compared to direct angiography. No difference in clinical success, complications, recurrence rates, or mortality was observed.

Sarcoidosis Versus Lymphoma?

An association between lymphoma and sarcoidosis was first suggested in 1960. We report a case of sarcoidosis-lymphoma syndrome, which is a diagnostically challenging condition. We conclude that an associated lymphoma should be considered in all patients with suspected sarcoidosis, especially those who do not respond to treatment or who present with persistent haematological abnormalities. Splenomegaly should prompt splenectomy to rule out lymphoma if a less invasive approach has failed to confirm the diagnosis. LEARNING POINTS: Clinical consideration should be given to an associated lymphoma in all patients with sarcoidosis, especially those who do not respond to treatment or who present with persistent haematological abnormalities.Splenomegaly should raise the possibility of splenectomy to rule out associated lymphoma.

Decrease in Pancreatic Perfusion of Patients with Type 2 Diabetes Mellitus Detected by Perfusion Computed Tomography.

OBJECTIVES: The objectives of the study was to compare pancreatic perfusion by computed tomography in type 2 diabetes and non-diabetic subjects. MATERIAL AND METHODS: In this case-control study, 17 patients with type 2 diabetes and 22 non-diabetic controls were examined with a dynamic 192-slices perfusion computed tomography for estimating pancreatic perfusion parameters. RESULTS: Thirty-nine patients were included (22 with Type 2 diabetes mellitus [T2DM]), with a mean age of 64 years. There were significant differences in some pancreatic perfusion parameters in patients with and without type 2 diabetes. Blood volume (BV) was lower in pancreatic head (with T2DM: 14.0 ± 3.4 vs. without T2DM: 16.1 ± 2.4 mL/100 mL; P = 0.033), pancreatic tail (with: 14.4 ± 3.6 vs. without: 16.8 ± 2.5 mL/100 mL; P = 0.023), and in whole pancreas (with: 14.2 ± 3.2 vs. without: 16.2 ± 2.5 mL/100 mL; P = 0.042). Similar behavior was observed with mean transit time (MTT) in pancreatic head (with: 7.0 ± 1.0 vs. without: 7.9 ± 1.2 s; P = 0.018), pancreatic tail (with: 6.6 ± 1.3 vs. without: 7.7 ± 0.9 s; P = 0.005), and in whole pancreas (with: 6.8 ± 1.0 vs. without: 7.7 ± 0.9 s; P = 0.016). BV in head, tail, and whole pancreas had negative correlations with age (head r: -0.352, P = 0.032; tail r: -0.421, P = 0.031; whole pancreas r: -0.439, P = 0.007), and fasting plasma glucose (head r: -0.360, P = 0.031; tail r: -0.483, P = 0.003; whole pancreas r: -0.447, P = 0.006). In a multivariate linear regression model, HbA1c was independently associated with decrease in BV in whole pancreas (ß: -0.884; CI95%: -1.750 to -0.017; P = 0.046). CONCLUSION: Pancreatic BV and MTT were significantly lower in patients with type 2 diabetes. BV was decreased with older age and poorer glycemic control.

Combined quality and dose-volume histograms for assessing the predictive value of 99mTc-MAA SPECT/CT simulation for personalizing radioembolization treatment in liver metastatic colorectal cancer.

BACKGROUND: The relationship between the mean absorbed dose delivered to the tumour and the outcome in liver metastases from colorectal cancer patients treated with radioembolization has already been presented in several studies. The optimization of the personalized therapeutic activity to be administered is still an open challenge. In this context, how well the 99mTc-MAA SPECT/CT predicts the absorbed dose delivered by radioembolization is essential. This work aimed to analyse the differences between predictive 99mTc-MAA-SPECT/CT and post-treatment 90Y-microsphere PET/CT dosimetry at different levels. Dose heterogeneity was compared voxel-to-voxel using the quality-volume histograms, subsequently used to demonstrate how it could be used to identify potential clinical parameters that are responsible for quantitative discrepancies between predictive and post-treatment dosimetry. RESULTS: We analysed 130 lesions delineated in twenty-six patients. Dose-volume histograms were computed from predictive and post-treatment dosimetry for all volumes: individual lesion, whole tumoural liver (TL) and non-tumoural liver (NTL). For all dose-volume histograms, the following indices were extracted: D90, D70, D50, Dmean and D20. The results showed mostly no statistical differences between predictive and post-treatment dosimetries across all volumes and for all indices. Notably, the analysis showed no difference in terms of Dmean, confirming the results from previous studies. Quality factors representing the spread of the quality-volume histogram (QVH) curve around 0 (ideal QF = 0) were determined for lesions, TL and NTL. QVHs were classified into good (QF < 0.18), acceptable (0.18 ≤ QF < 0.3) and poor (QF ≥ 0.3) correspondence. For lesions and TL, dose- and quality-volume histograms are mostly concordant: 69% of lesions had a QF within good/acceptable categories (40% good) and 65% of TL had a QF within good/acceptable categories (23% good). For NTL, the results showed mixed results with 48% QF within the poor concordance category. Finally, it was demonstrated how QVH analysis could be used to define the parameters that predict the significant differences between predictive and post-treatment dose distributions. CONCLUSION: It was shown that the use of the QVH is feasible in assessing the predictive value of 99mTc-MAA SPECT/CT dosimetry and in estimating the absorbed dose delivered to liver metastases from colorectal cancer via 90Y-microspheres. QVH analyses could be used in combination with DVH to enhance the predictive value of 99mTc-MAA SPECT/CT dosimetry and to assist personalized activity prescription.

Haemoptysis treated by bronchial artery embolisation in severe acute respiratory syndrome coronavirus 2: case report.

BACKGROUND: We found no data in the literature on the embolization of the bronchial arteries in the context of hemoptysis associated with severe acute respiratory syndrome coronavirus 2. We therefore decided to share this experience. CASE PRESENTATION: A 62-year-old patient with no significant medical history was admitted with acute respiratory distress. Chest computed tomography showed diffuse bilateral ground-glass opacities with limited consolidations. Diagnostic tests confirmed severe acute respiratory syndrome coronavirus 2 infection. The severity of respiratory failure required the implantation of veno-venous extracorporeal membrane oxygenation. The patient developed severe haemoptysis, which was successfully treated by bronchial artery embolisation. CONCLUSIONS: In the case of coronavirus-19 pneumonia, our experience suggests that the treatment of severe haemoptysis by bronchial artery embolisation is feasible and effective. The survival benefit should be assessed in the future.

Personalized selective internal radiation therapy in liver metastasis of thyroid cancer with impaired liver function: A case report.

Follicular thyroid cancer (FTC) is a less common form of differentiated thyroid cancer. Liver metastasis of differentiated thyroid cancer frequently occurs in the late onset of the metastatic disease, are often unrescetable and noniodine avid, leading to a poor prognosis. A 69-year-old man with a 14-year history of multi-metastatic follicular thyroid cancer was treated iteratively with 131-Iodine allowing to maintain a stable disease. Upon a recent exponential increase of the thyroglobulin, a peritoneal mass and a voluminous hepatic metastasis were discovered, comorbidities and an insufficient future remnant liver function excluded liver surgical resection. The tumour board proposed a resection of the peritoneal mass followed by selective internal radiation therapy of the liver mass. Due to the already impaired liver function, personalized dosimetry allowed a safe treatment delivering low activity to the nontumoral liver followed by a clinical and imaging response of the liver mass at 3 months. At our knowledge, this is the first case of thyroid liver metastasis treated by selective internal radiation therapy.

Retrospective analysis of the immunogenic effects of intra-arterial locoregional therapies in hepatocellular carcinoma: a rationale for combining selective internal radiation therapy (SIRT) and immunotherapy.

BACKGROUND: Immunotherapy represents a promising option for treatment of hepatocellular carcinoma (HCC) in cirrhotic patients but its efficacy is currently inconsistent and unpredictable. Locoregional therapies inducing immunogenic cell death, such as transarterial chemoembolization (TACE) or selective internal radiation therapy (SIRT), have the potential to act synergistically with immunotherapy. For the development of new approaches combining locoregional treatments with immunotherapy, a better understanding of the respective effects of TACE and SIRT on recruitment and activation of immune cells in HCC is needed. To address this question, we compared intra-tumor immune infiltrates in resected HCC after preoperative treatment with TACE or SIRT. METHODS: Data fromr patients undergoing partial hepatectomy for HCC, without preoperative treatment (SURG, n = 32), after preoperative TACE (TACE, n = 16), or preoperative SIRT (n = 12) were analyzed. Clinicopathological factors, tumor-infiltrating lymphocytes (TILs), CD4+ and CD8+ T cells, and granzyme B (GZB) expression in resected HCC, and postoperative overall and progression-free survival were compared between the three groups. RESULTS: Clinicopathological and surgical characteristics were similar in the three groups. A significant increase in TILs, CD4+ and CD8+ T cells, and GZB expression was observed in resected HCC in SIRT as compared to TACE and SURG groups. No difference in immune infiltrates was observed between TACE and SURG patients. Within the SIRT group, the dose of irradiation affected the type of immune infiltrate. A significantly higher ratio of CD3+ cells was observed in the peri-tumoral area in patients receiving < 100 Gy, whereas a higher ratio of intra-tumoral CD4+ cells was observed in patients receiving > 100 Gy. Postoperative outcomes were similar in all groups. Irrespective of the preoperative treatment, the type and extent of immune infiltrates did not influence postoperative survival. CONCLUSIONS: SIRT significantly promotes recruitment/activation of intra-tumor effector-type immune cells compared to TACE or no preoperative treatment. These results suggest that SIRT is a better candidate than TACE to be combined with immunotherapy for treatment of HCC. Evaluation of the optimal doses for SIRT for producing an immunogenic effect and the type of immunotherapy to be used require further evaluation in prospective studies.

Intra- and interobserver reproducibility of pancreatic perfusion by computed tomography.

The aim of this study was to measure intra- and interobserver agreement among radiologists in the assessment of pancreatic perfusion by computed tomography (CT). Thirty-nine perfusion CT scans were analyzed. The following parameters were measured by three readers: blood flow (BF), blood volume (BV), mean transit time (MTT) and time to peak (TTP). Statistical analysis was performed using the Bland-Altman method, linear mixed model analysis, and intraclass correlation coefficient (ICC). There was no significant intraobserver variability for the readers regarding BF, BV or TTP. There were session effects for BF in the pancreatic body and MTT in the pancreatic tail and whole pancreas. There were reader effects for BV in the pancreatic head, pancreatic body and whole pancreas. There were no effects for the interaction between session and reader for any perfusion parameter. ICCs showed substantial agreement for the interobserver measurements and moderate to substantial agreement for the intraobserver measurements, with the exception of MTT. In conclusion, satisfactory reproducibility of measurements was observed for TTP in all pancreatic regions, for BF in the head and BV in the tail, and these parameters seem to ensure a reasonable estimation of pancreatic perfusion.

Update on transarterial approaches to locoregional treatment in hepatocellular carcinoma.

PURPOSE OF REVIEW: This review explores current knowledge and recent data about vascular-centered locoregional treatments and proposes alternate algorithms. RECENT FINDINGS: Hepatocellular carcinoma represents the sixth most common neoplasm worldwide. Currently, the Barcelona Clinic Liver Cancer (BCLC) staging is the most commonly used in Europe for treatment allocation. According to this classification, European Society for Medical Oncology (ESMO) guidelines currently recommend transarterial chemoembolization for intermediate stage HCC and systemic treatments, such as, sorafenib in more advanced stages. However, strong evidences are still lacking to conclude to the superiority of one technique over another, as the optimal treatment choice remains challenging and should take into consideration more clinical, biological and imaging findings than reported in the BCLC staging system, such as patient age or clinical status, tumor characteristics (including distribution and heterogeneity), tumor vascularization and concomitant portal hypertension or biliary anomalies. SUMMARY: Many controversies remain, in particular, the relative place of bland embolization versus chemoembolization, the clinical benefit of drug-eluting bead chemoembolization (DEB-TACE) over conventional chemoembolization (cTACE), as well as the real place of radioembolization in general setting as well as innovative applications, such as radiation segmentectomy and radiation lobectomy.

Schwannoma of the colon and rectum: a systematic literature review.

BACKGROUND: Schwannomas of the colon and rectum are rare among gastrointestinal schwannomas. They are usually discovered incidentally as a submucosal mass on routine colonoscopy and diagnosed on pathologic examination of the operative specimen. Little information exists on the diagnosis and management of this rare entity. The aim of this study is to report a case of cecal schwannoma and the results of a systematic review of colorectal schwannoma in the literature. MAIN BODY: PubMed, Scopus, and Cochrane database searches were performed for case reports and case series of colonic and rectal schwannoma. Ninety-five patients with colonic or rectal schwannoma from 70 articles were included. Median age was 61.5 years (59% female). Presentation was asymptomatic (28%), rectorrhagia (23.2%), or abdominal pain (15.8%). Schwannoma occurred in the left and sigmoid colon in 36.8%, in the cecum and right colon in 30.5%, and in the rectum in 21.1%. Median tumor size was 3 cm and 56.2% of patients who underwent preoperative colonoscopy had a typical smooth submucosal mass. At pathology, 97.9, 13.7, and 5.3% of schwannomas stained positive for S100, vimentin, and GFAP, respectively. The median mitotic index was 1/50. CONCLUSIONS: Colorectal schwannoma is a very rare subtype of gastrointestinal schwannoma which occurs in the elderly, almost equally in men and women. Schwannoma should be included in the differential diagnosis of a submucosal lesion along with gastrointestinal stromal tumor, neuro-endocrine tumors, and leiomyoma-leiomyosarcoma. Definitive diagnosis is based on immunohistochemistry of the operative specimen. Rarely malignant, surgery is the mainstay of treatment.

Endovascular management of a rare complication of an aortic coarctation.

A 28-year-old pregnant woman presents with arterial hypertension of the upper limbs. The examination suggests an aortic coarctation. After a normal delivery, a contrast-enhanced computed tomography revealed a subocclusive aortic coarctation of the descending thoracic aorta and a 33-mm aneurysm developed from the left cervical-thoracic artery. The coarctation of the aorta was treated by a stent graft, and the aneurysm was treated by an injection of thrombin and glue.

90Y-PET/CT-based dosimetry after selective internal radiation therapy predicts outcome in patients with liver metastases from colorectal cancer.

BACKGROUND: The aim of this work was to confirm that post-selective internal radiation therapy (SIRT) 90Y-PET/CT-based dosimetry correlates with lesion metabolic response and to determine its correlation with overall survival (OS) in liver-only metastases from colorectal cancer (mCRC) patients treated with SIRT. Twenty-four mCRC patients underwent pre/post-SIRT FDG-PET/CT and post-SIRT 90Y-PET/CT. Lesions delineated on pre/post-SIRT FDG-PET/CT were classified as non-metabolic responders (total lesion glycolysis (TLG)-decrease < 15%) and high-metabolic responders (TLG-decrease ≥ 50%). Lesion delineations were projected on the anatomically registered 90Y-PET/CT. Voxel-based 3D dosimetrywas performed on the 90Y-PET/CT and lesions' mean absorbed dose (Dmean) was measured. The coefficient of correlation between Dmean and TLG-decrease was calculated. The ability of lesion Dmean to predict non-metabolic response and high-metabolic response was tested and two cutoff values (Dmean-under-treated and Dmean-well-treated) were determined using ROC analysis. Patients were dichotomised in the "treated" group (all the lesions received a Dmean > Dmean-under-treated) and in the "under-treated" group (at least one lesion received a Dmean < Dmean-under-treated). Kaplan-Meier product limit method was used to describe OS curves. RESULTS: Fifty-seven evaluable mCRC lesions were included. The coefficient of correlation between Dmean and TLG-decrease was 0.82. Two lesion Dmean cutoffs of 39 Gy (sensitivity 80%, specificity 95%, predictive-positive-value 86% and negative-predictive-value 92%) and 60 Gy (sensitivity 70%, specificity 95%, predictive positive-value 96% and negative-predictive-value 63%) were defined to predict non-metabolic response and high-metabolic response respectively. Patients with all lesions Dmean> 39 Gy had a significantly longer OS (13 months) than patients with at least one lesion Dmean < 39 Gy (OS = 5 months) (p = 0.012;hazard-ratio, 2.6 (95% CI 0.98-7.00)). CONCLUSIONS: In chemorefractory mCRC patients treated with SIRT, lesion Dmean determined on post-SIRT 90Y-PET/CT correlates with metabolic response and higher lesion Dmean is associated with prolonged OS.