Conventional and spectral- CT for renal cell carcinoma thermal ablation: A case report.

Dual-energy or spectral computed tomography (CT) information may be obtained by either sending X-ray beams of different energy spectra through the patient or by discriminating the energy of the X-rays that reach the detector. The spectral signal is then used to generate multiple results: conventional, virtual monoenergetic (MonoE), effective atomic number, electron density, and other material specific (e.g., iodine, calcium, or uric acid). This report demonstrates the potential benefits of spectral CT imaging during percutaneous tumor ablation procedures, specifically regarding visualization of inconspicuous tumors, accurate probe placement, and assessment of treatment efficacy.

Update on Percutaneous Ablation for Sarcoma.

PURPOSE OF REVIEW: To provide an update on the current state of percutaneous thermal ablation in the treatment of sarcoma. RECENT FINDINGS: Data continue to accrue in support of ablation for local control and palliation of specific sarcoma subtypes such as extra-abdominal desmoid fibromatosis and for broader indications such as the treatment of oligometastatic disease. The synergistic possibilities of various combination therapies such as cryoablation and immunotherapy represent intriguing areas of active investigation. Histotripsy is an emerging non-invasive, non-thermal ablative modality that may further expand the therapeutic arsenal for sarcoma treatment. Percutaneous thermal ablation is a valuable tool in the multidisciplinary management of sarcoma, offering a minimally invasive adjunct to surgery and radiation therapy. Although there remains a paucity of high-level evidence specific to sarcomas, ablation techniques are demonstrably safe and effective for achieving local tumor control and providing pain relief in select patients and are of particular benefit in those with metastatic disease or requiring palliative care.

Deep convolutional-neural-network-based metal artifact reduction for CT-guided interventional oncology procedures (MARIO).

BACKGROUND: Computed tomography (CT) is routinely used to guide cryoablation procedures. Notably, CT-guidance provides 3D localization of cryoprobes and can be used to delineate frozen tissue during ablation. However, metal-induced artifacts from ablation probes can make accurate probe placement challenging and degrade the ice ball conspicuity, which in combination could lead to undertreatment of potentially curable lesions. PURPOSE: In this work, we propose an image-based neural network (CNN) model for metal artifact reduction for CT-guided interventional procedures. METHODS: An image domain metal artifact simulation framework was developed and validated for deep-learning-based metal artifact reduction for interventional oncology (MARIO). CT scans were acquired for 19 different cryoablation probe configurations. The probe configurations varied in the number of probes and the relative orientations. A combination of intensity thresholding and masking based on maximum intensity projections (MIPs) was used to segment both the probes only and probes + artifact in each phantom image. Each of the probe and probe + artifact images were then inserted into 19 unique patient exams, in the image domain, to simulate metal artifact appearance for CT-guided interventional oncology procedures. The resulting 361 pairs of simulated image volumes were partitioned into disjoint training and test datasets of 304 and 57 volumes, respectively. From the training partition, 116 600 image patches with a shape of 128 × 128 × 5 pixels were randomly extracted to be used for training data. The input images consisted of a superposition of the patient and probe + artifact images. The target images consisted of a superposition of the patient and probe only images. This dataset was used to optimize a U-Net type model. The trained model was then applied to 50 independent, previously unseen CT images obtained during renal cryoablations. Three board-certified radiologists with experience in CT-guided ablations performed a blinded review of the MARIO images. A total of 100 images (50 original, 50 MARIO processed) were assessed across different aspects of image quality on a 4-point likert-type item. Statistical analyses were performed using Wilcoxon signed-rank test for paired samples. RESULTS: Reader scores were significantly higher for MARIO processed images compared to the original images across all metrics (all p < 0.001). The average scores of the overall image quality, iceball conspicuity, overall metal artifact, needle tip visualization, target region confidence, and worst metal artifact, needle tip visualization, iceball conspicuity, and target region confidence improved by 34.91%, 36.29%, 39.94%, 34.17%, 35.13%, and 45.70%, respectively. CONCLUSIONS: The proposed method of image-based metal artifact simulation can be used to train a MARIO algorithm to effectively reduce probe-related metal artifacts in CT-guided cryoablation procedures.

Normal and Abnormal Appearances of the Ovaries during Assisted Reproduction: Multimodality Imaging Review.

Infertility is a common diagnosis that prompts many couples and individuals to seek assisted reproductive technology (ART) for assistance with conception. These technologies have become increasingly used in the United States in the past several decades, with 326 468 ART cycles performed in 2020, resulting in 75 023 live births. This ubiquity of ART also increases the likelihood that radiologists will encounter both normal and abnormal imaging findings associated with these treatments. Thus, radiologists of all subspecialties should be familiar with the multimodality appearance of the ovaries and pelvis in patients undergoing ART treatments. Furthermore, it is imperative that radiologists understand the appearance expected during different stages of the ART process. During stimulated ovulatory cycles, it is normal and expected for the ovaries to appear enlarged and to contain numerous cystic follicles, often with a small to moderate volume of pelvic free fluid. After oocyte retrieval, hemorrhagic ovarian follicles and a small to moderate volume of blood products in the cul-de-sac can be expected to be seen. Multiple nonemergency and emergency complications are related to ART, many of which can be seen at imaging. The most encountered emergency complications of ART include ovarian hyperstimulation syndrome, ectopic pregnancy, heterotopic pregnancy, multiple gestations, ovarian torsion, and procedural complications related to oocyte retrieval. These complications have important clinical implications, thus necessitating accurate and timely detection by the radiologist and the clinical team. ©RSNA, 2023 Supplemental material is available for this article. Quiz questions for this article are available through the Online Learning Center.

Thermoprotection of Neural Structures During Musculoskeletal Ablation.

Percutaneous thermal ablation is widely used for local control and palliation of a variety of lesions throughout the musculoskeletal system. In this setting, safe ablation is predicated on the avoidance of unintentional injury to vulnerable neural structures that are often in proximity to ablation targets. This article highlights key periprocedural considerations in musculoskeletal ablation and reviews the array of active and passive thermoprotective measures that are critical to safe and successful treatment.

C11 choline PET/CT succeeds when conventional imaging for primary hyperparathyroidism fails.

BACKGROUND: Focused parathyroidectomy in primary hyperparathyroidism is possible with accurate preoperative localization. A growing body of data exists regarding the role of radio-labeled C11 choline positron emission tomography/computed tomography. In cases of nonlocalized disease, it may be a useful adjunct to ultrasound, (123)I/(99)Tc-sestamibi (I-123 sestamibi), or 4-dimensional computed tomography imaging. METHODS: Patients who received a neck and chest limited coverage C11 choline positron emission tomography/computed tomography for evaluation of primary hyperparathyroidism from 2017 to 2021 at a single institution were retrospectively reviewed. We assessed the sensitivity, positive predictive value, and false negative rate. We also compared these rates to the standard modalities of ultrasound, I-123 sestamibi, 4-dimensional computed tomography, and examined concordance rates. RESULTS: We identified 43 patients, of whom 33 had a positive C11 choline positron emission tomography/computed tomography finding. This cohort of patients had failed to localize on multiple standard imaging modalities. Twenty-five patients proceeded to surgery, 72% of whom were reoperative cases. Twenty (80%) achieved an intraoperative cure. Analysis showed that C11 choline positron emission tomography/computed tomography achieved a sensitivity of 64% (95% confidence interval 47%-82%) and positive predictive value of 72% (95% confidence interval 54%-90%). There were 5/25 (20%) false positive positron emission tomography C11 choline results found to be lymph nodes, normal parathyroid, and 1 recurrent laryngeal nerve neuroma. CONCLUSION: C11 choline positron emission tomography/computed tomography is a useful adjunct for parathyroid localization in a complex population of patients who have failed standard localization techniques including ultrasound, I-123 sestamibi, or 4-dimensional computed tomography and/or prior operations. Although routine inclusion of C11 choline positron emission tomography/computed tomography imaging may not be necessary, it may aid in preoperative localization in the reoperative setting.

Added value of mass characteristic frequency to 2-D shear wave elastography for differentiation of benign and malignant thyroid nodules.

Mass characteristic frequency (fmass) is a novel shear wave (SW) parameter that represents the ratio of the averaged minimum SW speed within the regions of interest to the largest dimension of the mass. Our study objective was to evaluate if the addition of fmass to conventional 2-D shear wave elastography (SWE) parameters would improve the differentiation of benign from malignant thyroid nodules. Our cohort comprised 107 patients with 113 thyroid nodules, of which 67 (59%) were malignant. Two-dimensional SWE data were obtained using the Supersonic Imagine Aixplorer ultrasound system equipped with a 44- to 15-MHz15-MHz linear array transducer. A receiver operating characteristic curve was generated based on a multivariable logistic regression analysis to evaluate the ability of SWE parameters with/without fmass and with/without clinical factors to discriminate benign from malignant thyroid nodules. The addition of fmass to conventional SW elasticity parameters increased the area under the curve from 0.808 to 0.871 (p = 0.02). The combination of SW elasticity parameters plus fmass plus clinical factors provided the strongest thyroid nodule malignancy probability estimate, with a sensitivity of 93.4% and specificity of 91.1% at the optimal threshold. In summary, fmass can be a valuable addition to conventional 2-D SWE parameters.

Percutaneous Cryoablation of Large Tumors: Safety, Feasibility, and Technical Considerations.

INTRODUCTION: Large tumors may prove unsuitable for surgical cure or other local therapies due to their size, involvement of critical structures, prior non-ablative treatment failure, or coexisting disease burden. This study was performed to assess the safety and feasibility of percutaneous cryoablation for treatment of large tumors exceeding 6 cm in size, and to highlight the key technical considerations inherent to such cases. MATERIALS AND METHODS: This single-institution retrospective study identified 77 patients (42 male, 35 female; median age 55 years) who underwent 96 cryoablation procedures for treatment of 78 tumors (mean diameter 9.8 ± 3.6 cm) from 2008 through 2020. Technical success, procedure-related complications, mortality, oncologic outcomes, and procedural logistics were evaluated. Technical success was defined as ice ball extension at least 5 mm beyond the tumor margins. RESULTS: Intentional subtotal ablations were performed in 32% of cases due to tumor encroachment on vulnerable structures or as part of staged/combined therapies. Of the 68% of cases that were planned for complete ablation, the technical success rate was 100%. Major complications occurred after 19/96 (20%) procedures, with hemorrhage and acute kidney injury each occurring in 6/96 (6%). Post-procedural myositis occurred in 24/96 (25%) cases and was not considered a major complication in the absence of acute kidney injury. Local recurrence occurred in 2/23 (8.7%) of patients undergoing ablation for cure or local control at a median follow-up duration of 13 months. CONCLUSION: Percutaneous cryoablation may be used to treat large (> 6 cm) tumors with a high degree of technical success and an acceptable safety profile.

Challenges in Diagnosis and Management of Hemobilia.

Hemobilia, or hemorrhage within the biliary system, is an uncommon form of upper gastrointestinal (GI) bleeding that presents unique diagnostic and therapeutic challenges. Most cases are the result of iatrogenic trauma, although accidental trauma and a variety of inflammatory, infectious, and neoplastic processes have also been implicated. Timely diagnosis can often be difficult, as the classic triad of upper GI hemorrhage, biliary colic, and jaundice is present in a minority of cases, and there may be considerable delay in the onset of bleeding after the initial injury. Therefore, the radiologist must maintain a high index of suspicion for this condition and be attuned to its imaging characteristics across a variety of modalities. CT is the first-line diagnostic modality in evaluation of hemobilia, while catheter angiography and endoscopy play vital and complementary roles in both diagnosis and treatment. The authors review the clinical manifestations and multimodality imaging features of hemobilia, describe the wide variety of underlying causes, and highlight key management considerations.©RSNA, 2021.

A Single-Institution Experience in Percutaneous Image-Guided Cryoablation of Lymph Node Metastases.

OBJECTIVE. The purpose of this study was to assess the feasibility, safety, and efficacy of percutaneous cryoablation for the treatment of lymph node metastases. MATERIALS AND METHODS. In this single-institution retrospective study 55 patients were identified who underwent CT-guided cryoablation of metastatic lymph nodes between November 2006 and September 2019. Patient demographics, disease characteristics, and procedural details were recorded. The primary endpoints were technical success and major complications. The secondary endpoints were time to local and time to distant progression. Complications were graded according to the Society of Interventional Radiology consensus guidelines. RESULTS. The study sample comprised 55 patients (42 men, 13 women; mean age 64 ± 12 years) who underwent 61 cryoablation procedures to treat 65 lymph node metastases. Targeted nodes measured 1.7 ± 1.2 cm in mean short-axis diameter. Technical success was achieved in 60 of 61 cryoablation procedures (98%). Adjunctive maneuvers performed to protect adjacent structures included hydrodissection (n = 40), ureteral stenting (n = 3), and neural monitoring (n = 3). There were two Society of Interventional Radiology major complications (3%): pneumothorax (n = 1) and bleeding (n = 1). Local tumor control was achieved in treatment of 53 of 65 (82%) nodal metastases within a median of 25 months (range, 1-121 months) of follow-up. Local progression occurred in 12 of 65 cases (18%); the median time to recurrence was 11 months. CONCLUSION. Percutaneous cryoablation of nodal metastases is feasible and safe. Further investigation is warranted to assess the long-term efficacy of this technique and to define its role in oncologic care.

Trends in Musculoskeletal Ablation: Emerging Indications and Techniques.

Image-guided percutaneous thermal ablation plays an increasingly important role in the multidisciplinary management of musculoskeletal lesions. Established indications for ablation in this setting include the treatment of osteoid osteomas, palliation of painful skeletal metastases, local control of oligometastatic disease, and consolidation of bone tumors at risk for fracture. Emerging indications include the treatment of symptomatic soft tissue masses such as extra-abdominal desmoid tumors and abdominal wall endometriosis. This review will discuss considerations in patient selection and preprocedural workup, ablation technology and techniques, strategies to avoid complications, and expected outcomes of ablation in the musculoskeletal system.

Cowden Syndrome: A Cause of Pulmonary Cysts.

OBJECTIVE: To describe the pulmonary imaging findings in patients with Cowden syndrome (CS). MATERIALS AND METHODS: A retrospective review identified all patients with CS who underwent dedicated computed tomography examinations of the chest at our institution between January 2000 and October 2017. Patient demographics and imaging characteristics were identified through a review of the electronic medical record and relevant imaging. RESULTS: Fifteen patients (6 males/9 females; mean age 53 y) with a clinical diagnosis of CS were identified. Genetic confirmation of the PTEN mutation was available in 8/15 (50%) patients. Pulmonary cysts were present in 12/15 (80%) patients and in 8/8 (100%) patients with documented PTEN mutations. The cysts ranged in size from 4 to 63 mm and were <10 in 10/12 (83%). Cysts were distributed randomly in 10/12 (83%) cases. Solid pulmonary nodules were present in 13/15 (87%) patients and were distributed randomly in all cases. CONCLUSIONS: Pulmonary cysts and solid nodules are common in patients with CS. Cysts tend to be distributed randomly, few in number, and may have traversing vessels. These findings should not be interpreted as evidence of another underlying disorder in the setting of CS.

11C-Choline PET/CT for Detection and Localization of Parathyroid Adenomas.

OBJECTIVE: The purpose of this study is to determine the efficacy of 11C-choline PET/CT for the detection of parathyroid adenomas by retrospectively reviewing a large patient population. MATERIALS AND METHODS: In this single-institution retrospective study, 7088 11C-choline PET/CT scans performed of 2933 men with prostate cancer from January 2005 through February 2016 were evaluated. Patients with suspected parathyroid adenomas were identified through a review of the electronic medical record and relevant imaging. Patient demographics, laboratory results, and lesion characteristics were noted. Pathologically proven parathyroid adenomas and lesions in patients with imaging or laboratory findings consistent with the diagnosis were considered positive. RESULTS: Thirteen men (mean [± SD] age, 72 ± 7 years) with pathologically or laboratory-proven parathyroid adenomas were identified. All had abnormally elevated serum calcium and parathyroid hormone levels. All adenomas were tracer avid on 11C-choline PET/CT (maximum standardized uptake value, 5.6 ± 3.0), with activity averaging 4.2 times that of the blood pool and 2.1 times that of the adjacent thyroid. One case of an ectopic adenoma was identified. Of the six pathologically confirmed cases, none displayed high-grade features such as capsular, vascular, or adjacent tissue invasion. Three additional patients with possible parathyroid adenomas at 11C-choline PET/CT were ultimately found to have thyroid lesions on the basis of tissue diagnosis; however, none of these patients had abnormal calcium or parathyroid hormone levels. CONCLUSION: In our patient population, 11C-choline PET/CT identified parathyroid adenomas with high specificity. Prospective investigation is warranted to validate this result and delineate the utility of 11C-choline PET/CT relative to other modalities.

Correlation of Doxorubicin Delivery and Tumor Necrosis after Drug-eluting Bead Transarterial Chemoembolization of Rabbit VX2 Liver Tumors.

Purpose To quantify the correlation between doxorubicin (DOX) delivery and tumor necrosis after drug-eluting bead (DEB) transarterial chemoembolization (TACE). Materials and Methods In this animal care committee-approved study, New Zealand white rabbit VX2 liver tumors were treated transarterially with DOX-loaded 70-150-µm DEBs in five treatment groups with varying drug doses: sham (saline), 0 mg, 12.5 mg, 25 mg, and 37.5 mg. DEB TACE was followed by 3- and 7-day sacrifice, tumor harvest, and sectioning. Drug delivery was assessed by using fluorescence imaging, and tumor necrosis was quantified by means of histologic analysis. Statistical correlation of DOX delivery and tumor necrosis was performed by using the Spearman rank correlation coefficient (ρ). Results Thirty-six VX2 tumors (median diameter, 1.3 cm) in 20 rabbits (median weight, 2.8 kg) underwent successful DEB TACE. Treatment groups included eight, seven, eight, five, and eight tumors of similar size (P > .05). Tumors showed progressively greater DOX extent (sham, 0%; 0 mg, 0%; 12.5 mg, 3%; 25 mg, 20%; and 37.5 mg, 27%) and intensity (sham, 0.4; 0 mg, 1.9; 12.5 mg, 8.5; 25 mg, 9.6; and 37.5 mg, 18.3) and higher median percentage necrosis (sham, 68%; 0 mg, 64%; 12.5 mg, 76%; 25 mg, 78%; and 37.5 mg, 83%) across DOX treatment groups. Correlation of DOX extent (ρ = 0.975, P = .005) and intensity (ρ = 0.900, P = .037) with percentage tumor necrosis was statistically significant. Conclusion Incremental increases in DOX correlate with greater necrosis in rabbit VX2 liver tumors after DEB TACE. This result indicates an essential role for chemotherapy-induced cytotoxicity in TACE effectiveness and supports the use of chemotherapeutic drugs in transarterial therapy. (©) RSNA, 2016 Online supplemental material is available for this article.

Pharmacokinetic study of conventional sorafenib chemoembolization in a rabbit VX2 liver tumor model.

PURPOSE: Use of oral sorafenib, an antiangiogenic chemotherapeutic agent for hepatocellular carcinoma (HCC), is limited by an unfavorable side effect profile. Transarterial chemoembolization (TACE) employs targeted intravascular drug administration, and has potential as a novel sorafenib delivery method to increase tumoral concentrations and reduce systemic levels. This study aimed to discern the pharmacokinetics of sorafenib TACE in a rabbit VX2 liver tumor model. METHODS: A 3 mg/kg dose of sorafenib ethiodized oil emulsion was delivered via an arterial catheter to VX2 liver tumors in seven New Zealand white rabbits. Following TACE, serum sorafenib levels were measured at days 0, 1, 2, 3, 7, 10, and 14 until the time of sacrifice, after which rabbit livers were harvested for analysis of sorafenib concentrations within treated tumors and normal liver. Liquid chromatography tandem mass spectrometry was used for drug quantification. RESULTS: Sorafenib uptake within liver tumor and nontumorous liver tissue peaked at mean 3.53 and 0.75 µg/mL, respectively, immediately post-procedure (5:1 tumor to normal tissue drug uptake ratio), before decreasing with a 10-18 hour half-life. Serum sorafenib levels peaked immediately after TACE at a mean value of 58.58 µg/mL before normalizing with a 5.2-hour half-life, suggesting early drug washout from liver into the systemic circulation. Hepatic lab parameters showed transient increase 24 hours post-TACE with subsequent resolution. CONCLUSION: While targeted transarterial delivery of sorafenib ethiodized oil emulsion shows preferential tumor uptake compared to normal liver, systemic washout occurs with a short half-life, resulting in high circulating drug levels.

Gene expression in hepatocellular carcinoma: pilot study of potential transarterial chemoembolization response biomarkers.

PURPOSE: To perform a feasibility study to explore the relationship between hepatocellular carcinoma genetics and transarterial chemoembolization treatment response to identify potential biomarkers associated with enhanced treatment efficacy. MATERIALS AND METHODS: In this single-institution study, pretreatment hepatocellular carcinoma biopsy specimens for tumors in 19 patients (14 men, five women; mean age, 59 y) treated with chemoembolization between 2007 and 2013 were analyzed for a panel of 60 chemotherapy-sensitivity, hypoxia, mitosis, and inflammatory genes with the QuantiGene Plex 2.0 mRNA detection assay. Demographic, disease, and procedure data and tumor response outcomes were collected. Quantitative mRNA levels were compared based on radiologic response between tumors exhibiting complete response (CR) versus partial response (PR). RESULTS: The study sample included 19 biopsy specimens from tumors (mean size, 3.0 cm; grade 1, n = 6; grade 2, n = 9; grade 3, n = 4) in patients treated with a mean of two conventional chemoembolization sessions. Thirteen and six tumors exhibited CR and PR, respectively, at a mean of 116 days after treatment. Tumors with CR showed a significant increase in (P < .05) or trend toward (P < .1) greater (range, 1.49-3.50 fold) pretreatment chemotherapy-sensitivity and mitosis (ATF4, BAX, CCNE1, KIF11, NFX1, PPP3CA, SNX1, TOP2A, and TOP2B) gene mRNA expression compared with tumors with PR, in addition to lower CXCL10 levels (0.48-fold), and had significantly (P < .05) higher (1.65-fold) baseline VEGFA levels. CONCLUSIONS: Genetic signatures may allow prechemoembolization stratification of tumor response probability, and gene analysis may therefore offer an opportunity to personalize locoregional therapy by enhancing treatment modality allocation. Further corroboration of identified markers and exploration of their respective predictive capacity thresholds is necessary.

Transcatheter renal interventions: a review of established and emerging procedures.

Catheter-based interventions play an important role in the multidisciplinary management of renal pathology. The array of procedures available to interventional radiologists (IRs) includes established techniques such as angioplasty, stenting, embolization, thrombolysis, and thrombectomy for treatment of renovascular disease, as well as embolization of renal neoplasms and emerging therapies such as transcatheter renal artery sympathectomy for treatment of resistant hypertension. Here, we present an overview of these minimally invasive therapies, with an emphasis on interventional technique and clinical outcomes of the procedure.

Clearing the Confusion over Hepatic Encephalopathy After TIPS Creation: Incidence, Prognostic Factors, and Clinical Outcomes.

PURPOSE: To assess the incidence, prognostic factors, and clinical outcomes of hepatic encephalopathy (HE) after transjugular intrahepatic portosystemic shunt (TIPS) creation. MATERIALS AND METHODS: In this single-institution retrospective study, 191 patients (m:f = 114:77, median age 54 years, median Model for End-Stage Liver Disease or MELD score 14) who underwent TIPS creation between 1999 and 2013 were studied. Medical record review was used to identify demographic characteristics, liver disease, procedure, and outcome data. Post-TIPS HE within 30 days was defined by new mental status changes and was graded according to the West Haven classification system. The influence of data parameters on HE occurrence and 90-day mortality was assessed using binary logistic regression. RESULTS: TIPS was successfully created with hemodynamic success in 99 % of cases. Median final PSG was 7 mmHg. HE incidence within 30 days was 42 % (81/191; 22 % de novo, 12 % stable, and 8 % worsening). Degrees of HE included grade 1 (46 %), grade 2 (29 %), grade 3 (18 %), and grade 4 (7 %). Medical therapy typically addressed HE, and shunt reduction was necessary in only three cases. MELD score (P = 0.020) and age (P = 0.009) were significantly associated with HE development on multivariate analysis. Occurrence of de novo HE post-TIPS did not associate with 90-day mortality (P = 0.400), in contrast to worsening HE (P < 0.001). CONCLUSIONS: The incidence of post-TIPS HE is non-trivial, but symptoms are typically mild and medically managed. HE rates are higher in older patients and those with worse liver function and should be contemplated when counseling on expected TIPS outcomes and post-procedure course.

Development, growth, propagation, and angiographic utilization of the rabbit VX2 model of liver cancer: a pictorial primer and "how to" guide.

The VX2 tumor is a leporine anaplastic squamous cell carcinoma characterized by rapid growth, hypervascularity, and facile propagation in the skeletal muscle. Since its introduction over 70 years ago, it has been used to model a variety of malignancies, and is commonly employed by interventional radiologists in preclinical investigations of hepatocellular carcinoma. However, despite the widespread and lasting popularity of the model, there are few technical resources detailing its use. Herein, we present a comprehensive pictorial outline of the technical methodology for development, growth, propagation, and angiographic utilization of the rabbit VX2 liver tumor model.

Characteristics of primary and secondary hepatic malignancies associated with hepatopulmonary shunting.

PURPOSE: To identify liver tumor characteristics associated with low (<10%), intermediate (10%-20%), and high (>20%) lung shunt fraction (LSF) at technetium 99m ((99m)Tc) macroaggregated albumin (MAA) imaging performed before yttrium 90 ((90)Y) radioembolization (RE). MATERIALS AND METHODS: In this single-center retrospective study, 141 patients (70 with hepatocellular carcinoma [HCC], 71 with other tumors; 95 men, 45 women; median age, 61 years) underwent mapping arteriography with (99m)Tc-MAA LSF calculation before (90)Y RE from 2006 to 2012. Tumor characteristics, including tumor type, index lesion size and morphologic structure (circumscribed, infiltrative), focality (solitary oligonodular, multinodular), disease distribution (unilobar, bilobar), tumor burden (≤50%, 50%), portal vein invasion (present, absent), and arterioportal shunting (present, absent) were correlated with (99m)Tc-MAA imaging-calculated LSFs at univariate and multivariate analysis. RESULTS: Median LSF was 8.4% (HCC, 9.0%; other tumors, 8.3%). LSF greater than 20% occurred in 14% of HCCs, but only in 3% of other tumors (P = .004). For HCC, tumor morphologic structure (P = .022), tumor burden (P < .001), main portal vein invasion (P = .033), and arterioportal shunting (P < .001) were significantly associated with different LSF categories at univariate analysis; infiltrative morphologic structure, tumor burden greater than 50%, portal vein invasion, and shunting had confirmed association with high LSF at multivariate analysis. For other liver tumors, tumor size (P = .001) and tumor burden (P = .003) were significantly associated with different LSF categories at univariate analysis. Multivariate confirmation was precluded by small sample size. Patients underwent a median of one (90)Y RE session (range, one to six), with median per-treatment and cumulative lung doses of 6.0 Gy and 8.5 Gy, respectively. CONCLUSION: LSF greater than 20% periodically occurs in HCC but is uncommon in other liver tumors. Specific tumor characteristics are associated with LSF greater than 20% and may indicate need for interventions to reduce LSF.