Virtual Injection Software Reduces Radiation Exposure and Procedural Time of Prostatic Artery Embolization Performed with Cone-Beam CT.

PURPOSE: To evaluate the impact of virtual injection software (VIS) use during cone-beam computed tomography (CT)-guided prostatic artery embolization (PAE) on both patient radiation exposure and procedural time. MATERIALS AND METHODS: This institutional review board (IRB)-approved comparative retrospective study analyzed the treatment at a single institution of 131 consecutive patients from January 2020 to May 2022. Cone-beam CT was used with (Group 1, 77/131; 58.8%) or without VIS (Group 2, 54/131, 41.2%). Radiation exposure (number of digital subtraction angiography [DSA] procedures), dose area product (DAP), total air kerma (AK), peak skin dose (PSD), fluoroscopy time (FT), and procedure time (PT) were recorded. The influences of age, body mass index, radial access, and use of VIS were assessed. RESULTS: In bivariate analysis, VIS use (Group 1) showed reduction in the number of DSA procedures (8.6 ± 3.7 vs 16.8 ± 4.3; P < .001), DAP (110.4 Gy·cm2 ± 46.8 vs 140.5 Gy·cm2 ± 61; P < .01), AK (642 mGy ± 451 vs 1,150 mGy ± 637; P = .01), PSD (358 mGy ± 251 vs 860 mGy ± 510; P = .001), FT (35.6 minutes ± 15.4 vs 46.6 minutes ± 20; P = .001), and PT (94.6 minutes ± 41.3 vs 115.2 minutes ± 39.6, P = .005) compared to those in Group 2. In multivariate analysis, AK, PSD, FT, and PT reductions were associated with VIS use (P < .001, P < .001, P = .001, and P = .006, respectively). CONCLUSIONS: The use of VIS during PAE performed under cone-beam CT guidance led to significant reduction in patient radiation exposure and procedural time.

Incidental findings in cone beam computed tomography volumes: Calcified head-and-neck atheromas detected during dental evaluation.

PURPOSE: Atheromas can be detected incidentally in routine dental cone beam computed tomography (CBCT) images. This study aims to assess prevalence and risk factors associated with these vascular lesions. MATERIALS AND METHODS: The maxillofacial CBCTs of 458 subjects were evaluated and divided into 4 groups based on the presence of calcified atheroma: subjects with no calcified atheroma, subjects with intracranial calcified atheroma (ICA), subjects with extracranial calcified atheroma (ECA), and subjects exhibiting combined lesions. Age, sex, medical conditions, family history, and size were documented. Analysis of variance followed by a multiple comparison test was used for data satisfying parametric test assumptions. Chi-squared tests were used to assess categorical data. The Spearman Rho test was used to assess the correlation between the incidence of calcified atheroma and subjects' medical condition. RESULTS: Of the 458 CBCTs evaluated, 29.90% presented with calcified atheroma. Calcified atheroma prevalence was significantly higher in older patients versus younger patients (p = 0.004) and in males compared to females (p = 0.004). Males were more likely to have the combination of ICA and ECA, whereas females were more likely to have ICA alone (p ≤ 0.040). Patients with calcified atheroma were significantly more likely to have a history of hyperlipidemia (p = 0.001), hypertension (p = 0.001), and myocardial infarction/coronary artery diseases (p = 0.001). Overall, patients exhibiting both intracranial and extracranial lesions were more likely to have cardiovascular risk factors (p = 0.001). CONCLUSION: Incidentally detected calcified atheromas in CBCTs are common. Subjects with combined atheroma lesions are at higher risk for cardiovascular disease. The diagnosis of incidental calcified atheromas in CBCT's warrants early referral to medical specialists, especially if there is no medical history of existing cardiovascular disease.

Can Weightbearing Cone-beam CT Reliably Differentiate Between Stable and Unstable Syndesmotic Ankle Injuries? A Systematic Review and Meta-analysis.

BACKGROUND: Ankle injuries are common presentations to the emergency department and may lead to syndesmotic instability. These have a high socioeconomic burden due to prolonged rehabilitation, chronic pain, and posttraumatic arthritis. Early diagnosis is essential to minimize these complications, and the assessment of instability in the clinical setting is often limited by pain and clinician experience. Cross-sectional imaging of the distal syndesmosis accurately evaluates the syndesmosis through abnormal bony relationships, which in the presence of instability, worsens during physiological loading. Cone-beam CT (CBCT) has gained popularity in the diagnosis of these injuries because it enables syndesmotic assessment under weightbearing conditions, it mitigates the high radiation dose, and it is time-efficient. QUESTIONS/PURPOSES: The purposes of this systematic review were: (1) to establish normal values for weightbearing CBCT of the syndesmosis in uninjured ankles and ascertain interobserver reliability and (2) to identify the impact of weightbearing on the syndesmosis in patients with occult ankle injuries and assess the effect of patient demographics on these metrics. METHODS: This systematic review was reported in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and registered in PROSPERO (ID CRD42021248623). MEDLINE, PubMed, Embase, and Emcare databases were searched for studies assessing for syndesmotic instability, of which 307 studies were screened and 11 studies with 559 ankles in 408 uninjured patients and 151 patients with syndesmotic instability were included. All patients 18 years of age or older presenting with unilateral ankle injuries who underwent weightbearing CBCT for the diagnosis of an occult fracture or syndesmotic instability compared with the uninjured contralateral side were included. A control group of uninjured ankles was identified during weightbearing CBCT performed for other indications such as forefoot or midfoot injuries. Methodological assessment of the studies was performed using the Risk of Bias In Non-randomized Studies (ROBINS-1) tool and most included studies had a low risk of bias. Thus, a random-effects restricted maximum likelihood ratio model was used. RESULTS: In the uninjured ankle, the mean area of the tibiofibular syndesmosis was 112.5 ± 7.1 mm 2 , which increased to 157.5 ± 9.6 mm 2 after injury when compared with uninjured ankles with a standardized mean difference of 29.5 (95% confidence interval 19.5 to 39.5; p < 0.01), and an excellent interobserver agreement (κ = 1.0 [95% CI 0.9 to 1.0]). However, syndesmosis volume decreased with age (ß = -0.76; p = 0.04), and therefore, has a negative association with increasing age. CONCLUSION: Our study has shown that the syndesmotic area is the most reliable parameter in the assessment of syndesmotic injuries because it increases in the presence of instability during weightbearing status. It is a composite measurement that could potentially allow clinicians to use weightbearing CBCT as an adjunct when there is a clinical suspicion of syndesmotic instability. Thus, weightbearing CBCT has the potential of being diagnostic of syndesmotic instability and should be evaluated against current radiological modalities to evaluate its accuracy. LEVEL OF EVIDENCE: Level IV, prognostic study.

Management of Multiple Idiopathic Root Resorption in a Rheumatoid Arthritis Patient: A Case Report with 4-year Follow-up.

Cervical root resorption is a rare destructive disease that originates from the external cervical root surface. It has a multifactorial etiology. Cervical root resorption may affect several teeth and its treatment can be complicated due to the size, location, and extension of the resorptive defect. Rheumatoid arthritis is a chronic inflammatory autoimmune disease that has systemic effects. The objective of this article was to report a rare case of multiple idiopathic cervical resorptions in a patient with rheumatoid arthritis. A 52-year-old male patient with a 20-year history of rheumatoid arthritis was diagnosed with multiple idiopathic cervical resorptions through cone-beam computed tomography (CBCT) and clinical examination. All known causes for cervical resorption were ruled out after a detailed anamnesis. This report details inflammation due to rheumatoid arthritis as a possible cause of idiopathic cervical resorption. The systemic alterations wrought by rheumatoid arthritis could be related to the etiopathogenesis of cervical root resorption. Non-surgical endodontic treatment was done for the maxillary left canine. The defect was surgically repaired using bioceramic putty. The 12-month recall revealed the good healing of the periodontal and periradicular conditions with no obvious clinical symptoms. At the 36-month recall visit, clinical and radiographic evidence of deterioration in the repair material was observed. At the 54-month follow-up, deterioration of repair material was observed with an increase in the extension of resorption in tooth 14 was detected. Reasons for this deterioration remain unclear. Ruling out all other factors for cervical root resorption, how rheumatoid arthritis contributes to cervical root resorption is still lacking/unclear. Dental care providers must be vigilant for signs of cervical root resorption in vulnerable patients with rheumatoid arthritis for early diagnosis and prompt treatment. Keywords: External root resorption, Inflammatory markers, Multiple root resorption, Rheumatoid arthritis, Resorption repair.

Etiology of Tinnitus on CT and CBCT: A Narrative Review.

Tinnitus is commonly depicted as a ringing within the ears, but it can sound like roaring, clicking, hissing, or buzzing. It is a symptom that shows something is wrong in the auditory system, which includes the sound-related nerve that interfaces the inward ear to the brain, and the parts of the brain that handle sound. Generally, the causes of tinnitus include: Otologic causes, Neurologic causes, temporomandibular joint, and masticatory muscle disorders. Causes of tinnitus can be diagnosed with CT and CBCT. A CT scan or computed tomography scan is a medical imaging technique used in radiology that can obtain detailed internal images of the brain and CBCT is a developing imaging technique designed to provide relatively low-dose high-spatial-resolution visualization of highcontrast structures in the head and neck and other anatomic areas. CBCT has a lower radiation dose, shorter imaging time, and better resolution than CT. This chapter reviews etiology of tinnitus on CT and CBCT.

Moderately hypofractionated radiotherapy for localized prostate cancer: updated long-term outcome and toxicity analysis.

PURPOSE: Evaluation of long-term outcome and toxicity of moderately hypofractionated radiotherapy using intensity-modulated radiotherapy (IMRT) with simultaneous integrated boost treatment planning and cone beam CT-based image guidance for localized prostate cancer. METHODS: Between 2005 and 2015, 346 consecutive patients with localized prostate cancer received primary radiotherapy using cone beam CT-based image-guided intensity-modulated radiotherapy (IG-IMRT) and volumetric modulated arc therapy (IG-VMAT) with a simultaneous integrated boost (SIB). Total doses of 73.9 Gy (n = 44) and 76.2 Gy (n = 302) to the high-dose PTV were delivered in 32 and 33 fractions, respectively. The low-dose PTV received a dose (D95) of 60.06 Gy in single doses of 1.82 Gy. The pelvic lymph nodes were treated in 91 high-risk patients to 45.5 Gy (D95). RESULTS: Median follow-up was 61.8 months. The 5­year biochemical relapse-free survival (bRFS) was 85.4% for all patients and 93.3, 87.4, and 79.4% for low-, intermediate-, and high-risk disease, respectively. The 5­year prostate cancer-specific survival (PSS) was 94.8% for all patients and 98.7, 98.9, 89.3% for low-, intermediate-, and high-risk disease, respectively. The 5­year and 10-year overall survival rates were 83.8 and 66.3% and the 5­year and 10-year freedom from distant metastasis rates were 92.2 and 88.0%, respectively. Cumulative 5­year late GU toxicity and late GI toxicity grade ≥2 was observed in 26.3 and 12.1% of the patients, respectively. Cumulative 5­year late grade 3 GU/GI toxicity occurred in 4.0/1.2%. CONCLUSION: Moderately hypofractionated radiotherapy using SIB treatment planning and cone beam CT image guidance resulted in high biochemical control and survival with low rates of late toxicity.

Improving Cone-Beam CT Angiography for Prostatic Artery Embolization: Is a Low-Dose Protocol Equivalent to the Standard?

PURPOSE: To compare the utility of low-dose versus standard cone-beam computed tomography (CT) angiography protocols in identifying nontarget embolization (NTE) during prostatic artery embolization (PAE). MATERIALS AND METHODS: A prospective, single-center, Phase-1 study (NCT02592473) was conducted for lower urinary tract symptoms in benign prostatic hyperplasia. Prostate volume, international prostate symptom score (IPSS), quality of life score (QoL), International Index of Erectile Function (IIEF), peak flow rate, UCLA Prostate Cancer Index (UCLA-PCI), and postvoid residual were recorded at baseline and 1, 3, 6, 12, and 24-months after PAE. Six-second (standard protocol, n = 29) or 5-second (low-dose protocol n = 45) rotations were made. Images were selected and matched in pairs by areas of NTE and compared by readers using a binomial generalized estimating equation model. Procedural outcomes were analyzed using a linear mixed model. RESULTS: Seventy-four cone-beam CT angiographies were performed in 21 patients. IPSS and QoL scores significantly improved (P <.05). There was no change in UCLA-PCI or IIEF scores. Dose area product of the low- and standard-dose protocol were 37,340.82 mGy·cm2 ± 104.66 and 62,645.66 mGy·cm2 ± 12,711.48, respectively, representing a dose reduction of 40.4%. A total of 120 comparisons showed no preference between the 2 protocols (P =.24). Observers identified 76 and 69 instances of NTE in the standard- and low-dose protocols, respectively (P =.125). CONCLUSIONS: Low-dose cone-beam CT angiography achieved equivalent clinical utility in identifying NTE during PAE, with the advantage of a lower radiation dose.

Radiation Dose during Transarterial Radioembolization: A Dosimetric Comparison of Cone-Beam CT and Angio-CT Technologies.

PURPOSE: To evaluate the radiation dose differences for intraprocedural computed tomography (CT) imaging between cone-beam CT and angio-CT acquired during transarterial radioembolization (TARE) therapies for hepatocellular carcinoma. MATERIALS AND METHODS: A retrospective cohort of 22 patients who underwent 23 TARE procedures were selected. Patients were imaged in both cone-beam CT and angio-CT rooms as a part of their conventional treatment plan. Effective dose contributions from individual CT acquisitions as well as the cumulative dose contributions from procedural 3D imaging were evaluated. Angiography dose contributions were omitted. Cone-beam CT images were acquired on a C-arm Philips Allura system. Effective doses were evaluated by coupling previously published conversion factors (effective dose per dose-area product) to patient's dose-area product meter readings after the procedure. Angio-CT images were acquired on a hybrid Canon Infinix-i Aquilion PRIME system. Effective doses from angio-CT scans were estimated using Radimetrics. Comparisons of a single patient's dose differential between the 2 technologies were made. RESULTS: The mean effective dose from a single CT scan was 6.42 mSv and 5.99 mSv in the cone-beam CT room and the angio-CT room, respectively (P = .3224), despite the greater field of view and average craniocaudal scan coverage in angio-CT. The mean effective dose summed across all CTs in a procedure was 12.89 mSv and 34.35 mSv in the cone-beam CT room and the angio-CT room, respectively (P = .0018). CONCLUSIONS: The mean effective dose per CT scan is comparable between cone-beam CT and angio-CT when considered in direct comparison for a single patient.

What Is the Diagnostic Accuracy of Flat-panel Cone-beam CT Arthrography for Diagnosis of Scapholunate Ligament Tears?

BACKGROUND: Cone beam CT (CBCT) is a widely available technique with possible indications in carpal ligament injuries. The accuracy of CBCT arthrography in diagnosing traumatic tears of the scapholunate ligament has not been reported. QUESTIONS/PURPOSES: (1) What is the diagnostic accuracy of CBCT and how does it relate to the accuracy of multislice CT arthrography and conventional arthrography in diagnosing scapholunate ligament tears? (2) What is the estimated magnitude of skin radiation doses of each method? METHODS: This secondary analysis of a previous prospective study included 71 men and women with suspected scapholunate ligament tears and indications for arthroscopy. Preoperative imaging was conventional arthrography and either MSCT arthrography for the first half of patients to be included (n = 36) or flat-panel CBCT arthrography for the remaining patients (n = 35). Index tests identified therapy-relevant SLL tears with dorsal or complete SLL ruptures, and these tears were compared with relevant SLL tears which were determined through arthroscopy as Geissler Stadium III and IV by probing the instable SL joint with a microhook or arthroscope. These injuries were treated by open ligament repair and Kirschner wire fixation. Accuracy values and 95% confidence intervals were calculated. Additional estimates of the radiation skin doses of each CBCT exam and two MSCT protocols were subsequently calculated using dose area products, dose length products, and CT dose indices. RESULTS: The diagnostic accuracy was high for all imaging methods. 95% CIs were broadly overlapping and therefore did not indicate differences between the diagnostic groups: Sensitivity of CBCT arthrography was 100% (95% CI 77 to 100), specificity was 95% (95% CI 76 to 99.9), positive predictive value was 93% (95% CI 68 to 99.8), and negative predictive value was 100% (95% CI 83 to 100). For MSCT arthrography, the sensitivity was 92% (95% CI 64 to 99.8), specificity was 96% (95% CI 78 to 99.9), positive predictive value was 92% (95% CI 64 to 99.8), and negative predictive value was 96% (95% CI 78 to 99.9). For conventional arthrography, the sensitivity was comparably high: 96% (95% CI 81 to 99.9). Specificity was (81% [95% CI 67 to 92]); the positive predictive value was 77% (95% CI 59 to 89) and negative predictive value was 97% (95% CI 86 to 99.9). Estimated mean (range) radiation skin doses were reported in a descriptive fashion and were 12.9 mSv (4.5 to 24.9) for conventional arthrography, and 3.2 mSv (2.0 to 4.8) for CBCT arthrography. Estimated radiation skin doses were 0.2 mSv and 12 mSv for MSCT arthrography, depending on the protocol. CONCLUSION: Flat-panel CBCT arthrography can be recommended as an accurate technique to diagnose scapholunate ligament injuries after wrist trauma. Estimated skin doses are low for CBCT arthrography and adapted MSCT arthrography protocols. LEVEL OF EVIDENCE: Level III, diagnostic study.

Impact of onlay fusion and cone beam computed tomography on radiation exposure and technical assessment of fenestrated-branched endovascular aortic repair.

OBJECTIVE: The objective of this study was to analyze the impact of advanced imaging applications and cone beam computed tomography (CBCT) on radiation exposure of the patient and operator and detection of technical problems during fenestrated-branched endovascular aortic repair (F-BEVAR) for treatment of pararenal aneurysms and thoracoabdominal aortic aneurysms (TAAAs). METHODS: We reviewed the clinical data of 386 consecutives patients (289 male; mean age, 75 ± 8 years) treated by F-BEVAR for 196 pararenal aneurysms and 190 TAAAs (mean, 3.4 ± 0.9 targeted vessels/patient) between 2007 and 2017. Radiation exposure (cumulative air kerma) was analyzed in three fixed imaging systems used between 2007 and 2011 (system 1), 2012 and 2016 (system 2), and 2016 and 2017 (system 3). Onlay fusion and CBCT were available with systems 2 and 3, whereas digital zoom with fusion overlay was used with system 3. Operator effective dose was measured per month using a radiation dosimeter badge. Computed tomography angiography and CBCT were analyzed for findings requiring immediate revision or secondary interventions. End points were patient radiation exposure; operator effective dose; procedure technical success; and 30-day rates of mortality, major adverse events, and secondary interventions. RESULTS: F-BEVAR was performed using system 1 in 98 patients, system 2 in 198 patients, and system 3 in 90 patients. Use of onlay fusion/CBCT was 0% with system 1, 42% with system 2, and 98% with system 3. Procedures performed with onlay fusion/CBCT had significantly (P < .05) higher technical success (99.4% vs 98.8%) and lower contrast material volume (155 ± 58 mL vs 172 ± 80 mL), fluoroscopy time (83 ± 34 minutes vs 94 ± 49 minutes), and cumulative air kerma (2561 ± 1920 mGy vs 3767 ± 2307 mGy). Despite higher case volume and increasing complexity during the experience, operator effective dose decreased to 9 ± 4 × 10-2 mSv/case with system 3 compared with 26 ± 3 × 10-2 mSv/case with system 1 and 20 ± 2 × 10-2 mSv/case with system 2 (P = .001). Among 219 patients who had no CBCT, 18 (8%) had computed tomography angiography findings that prompted secondary interventions before dismissal. Conversely, among 167 patients who had CBCT, 14 patients (8%) had intraoperative CBCT findings requiring immediate revision, with no additional secondary interventions. Patients treated with onlay fusion/CBCT had significantly (P < .05) lower mortality (4% vs 1%), major adverse events (43% vs 19%), and secondary interventions (10% vs 4%) at 30 days. CONCLUSIONS: Radiation exposure and operator effective dose significantly decreased with evolution of F-BEVAR experience and use of advanced imaging applications such as onlay fusion and CBCT. CBCT allowed immediate assessment and identified intraoperative technical problems, leading to immediate revision and avoiding early secondary interventions.

Dental Cone Beam Computed Tomography in Children: Clinical Effectiveness and Cancer Risk due to Radiation Exposure.

Firstly used in the early 90s to generate 3-dimensional projections of X-ray images, cone beam computed tomography (CBCT) has resulted in a large application in dentomaxillofacial imaging, even in children. CBCT uses ionizing radiation that may cause damage to the DNA, and children are at the greatest carcinogenesis risk due to their higher tissue radiosensitivity and their longer life expectancy compared to adults. The questions of whether the cancer risk is really increased after repeated dental CBCT in childhood and of what the underlying biological basis is have become hot topics in the field of dentistry and radiobiology. We performed an overview of the current literature to assess an acceptable role of CBCT in pediatric dentistry.

Safety and Efficacy of Combined Transarterial Embolization and Percutaneous Radiofrequency Ablation for Liver Tumors Using Cone-Beam CT and Needle Navigation Software in a Single Session.

PURPOSE: To assess the safety and efficacy of single-session transarterial embolization and radiofrequency (RF) ablation for hepatic tumors with the use of needle navigation software. MATERIALS AND METHODS: Retrospective analysis was conducted of 24 patients with liver cancer undergoing embolization followed by RF ablation between May 2014 and August 2017. Twelve patients each underwent (i) embolization and computed tomography (CT)-guided RF ablation during different sessions (group 1) and (ii) embolization followed by RF ablation with cone-beam CT and Needle Assist software in 1 session (group 2). Median age (70.5 y [range, 58-78 y] vs 70.5 y [range, 50-82 y]; P = .76) and performance status (0/1) were comparable between groups. Median tumor size was significantly larger in group 2 (2 cm [range, 1.0-7.3 cm] vs 3.2 cm [range, 1.1-9.6 cm]; P < .03). Procedure time, effective dose, and number of scans were examined. Efficacy was assessed by modified Response Evaluation Criteria In Solid Tumors after 1 month. Safety was assessed by Society of Interventional Radiology adverse event classification. RESULTS: Group 1 had a mean of 8.5 CT scans, vs a mean of 5.0 cone-beam CT scans in group 2 (P < .001). Median procedure times were 110 min in group 1 and 199.5 min in group 2 (P < .001). Median effective doses were 68.8 mSv in group 1 and 55.4 mSv in group 2 (P = .38). There was no difference in complete response between groups (66.7% vs 63.6%; P = 1). CONCLUSIONS: Transarterial embolization followed by RF ablation with cone-beam CT and needle guidance software in a single session seems to be safe and effective.

Radiation Dose in Prostatic Artery Embolization Using Cone-Beam CT and 3D Roadmap Software.

PURPOSE: To evaluate the radiation dose in patients undergoing prostatic artery embolization (PAE) using cone-beam CT and 3-dimensional (3D) guidance software. MATERIALS AND METHODS: In this single-center retrospective study, 100 patients with benign prostatic hyperplasia (mean prostate volume, 83.6 mL ± 44.2; 69.4 ± 9.6 years of age; body mass index, 26.5 ± 4.2) were treated using PAE between October 2016 and April 2018. Informed consent was obtained from all participants included in the study. All patients received at least 1 intraprocedural cone-beam CT per side for evaluation of the vessel anatomy and software rendering of 3D guidance for catheter guidance. Digital subtraction angiography (DSA) was performed in the distal branches only. The total dose area product (DAP), along with the DAP attributed to fluoroscopy, DSA, and cone-beam CT, were assessed. RESULTS: Bilateral embolization was achieved in 83 patients (83%). The average total DAP was 134.4 Gy ⋅ cm2 ± 69.5 (range, 44.7-410.9 Gy ⋅ cm2). Fluoroscopy, DSA, and cone-beam CT accounted for 35.5 Gy ⋅ cm2 ± 21.3 (range, 8.6-148.6 Gy ⋅ cm2) or 26.4% (percentage of total DAP), 58.2 Gy ⋅ cm2 ± 48.3 (range, 10.3-309.3 Gy ⋅ cm2) or 43.3%, and 40.7 Gy ⋅ cm2 ± 14.5 (range, 15.9-86.3 Gy ⋅ cm2) or 30.3%, respectively. Average procedure time was 89.4 ± 27.0 minutes, and the average fluoroscopy time was 30.9 ± 12.2 minutes. CONCLUSIONS: Intraprocedural cone-beam CT in combination with 3D guidance software allows for identification and catheterization of the prostatic artery in PAE. Furthermore, the results of this trial indicate that this study protocol may lead to a low overall radiation dose.

Cone-Beam CT-Guided Chemoembolization in Patients with Complete Response after Previous Chemoembolization but Subsequent Elevated α-Fetoprotein without Overt Hepatocellular Carcinoma.

PURPOSE: To evaluate the performance of C-arm computed tomography (CT)-guided chemoembolization in patients with hepatocellular carcinoma (HCC) with serum α-fetoprotein (AFP) level > 20 ng/mL but with no overt tumor on CT and/or magnetic resonance imaging. MATERIALS AND METHODS: From May 2010 to May 2017, 34 patients with HCC (25 men and 9 women; mean age, 59.7 y) who had elevated serum AFP levels (> 20 ng/mL) but no overt tumor on 6-mo imaging studies and had shown complete response (CR) after previous chemoembolization underwent C-arm CT-guided conventional chemoembolization. Three radiologists retrospectively reviewed the imaging studies (preprocedural images, C-arm CT scans, and follow-up images) in consensus, and clinical data including AFP levels were retrospectively obtained. Tumor detection by C-arm CT and treatment response after chemoembolization were assessed. RESULTS: HCC was imaged at the time of chemoembolization in 24 of 34 patients (70.6%). C-arm CT detected tumors in 25 patients (73.5%); 23 detections were true positives, 2 were false positives, and 1 was a false negative (diaphragm metastasis). Among the 23 patients with true-positive results, the first follow-up enhanced imaging studies showed CR (n = 17), partial response (n = 1), progressive disease (n = 4), and indeterminate status (n = 1; treated by percutaneous ethanol injection). CONCLUSIONS: C-arm CT-guided chemoembolization may help to detect and treat recurrent tumors in patients who have shown CR after previous chemoembolization but subsequently, during follow-up surveillance, had serum AFP levels > 20 ng/mL without an overt tumor evident on imaging studies.

Outcomes of Patients with Hepatocellular Carcinoma Treated with Conventional Transarterial Chemoembolization Using Guidance Software.

PURPOSE: To evaluate the outcomes of conventional transarterial chemoembolization using guidance software for hepatocellular carcinoma (HCC) patients. MATERIALS AND METHODS: One hundred two patients with treatment-naïve HCC with ≤ 7-cm and ≤ 5 lesions treated with conventional transarterial chemoembolization using guidance software were selected. Technical success was classified into 3 grades by computed tomography performed 1 week after transarterial chemoembolization: (i) A, complete embolization with a safety margin; (ii) B, entire tumor embolization without a safety margin; and (iii) C, incomplete embolization. Intrahepatic tumor recurrence was classified into 2 categories: local tumor progression (LTP) and intrahepatic distant recurrence (IDR). Overall survival (OS) and tumor recurrence rates were calculated by the Kaplan-Meier method. Additionally, the incidences of LTP between grade A and B tumors, IDR with/without LTP, and OS with/without LTP were compared by the log-rank test. RESULTS: One hundred fifty-six (82.1%) tumors were determined to be grade A, 26 (13.7%) were determined to be grade B, and 8 (4.2%) were determined to be grade C. The 1-, 3-, and 5-year LTP and IDR rates were 31.7%, 49.4%, and 59.4% and 33.9%, 58.2%, and 73.3%, respectively. LTP developed more frequently in grade B tumors than grade A tumors (P = .0016). IDR developed more frequently in patients with LTP than without LTP (P = .0004). The 1-, 3-, and 5-year OS rates were 96.1%, 71.1%, and 60%, respectively; the 1-, 3-, and 5-year OS rates in patients with/without LTP were 95.7%, 69.8%, and 59.3% and 96.2%, 71.6%, and 59.4%, respectively (P = .9984). CONCLUSIONS: Transarterial chemoembolization guidance software promotes the technical success of transarterial chemoembolization and excellent OS in HCC patients.

Safety and accuracy of spinal instrumentation surgery in a hybrid operating room with an intraoperative cone-beam computed tomography.

Although spinal instrumentation technique has undergone revolutionary progress over the past few decades, it may still carry significant surgery-related risks. The purpose of the present study was to assess the radiological accuracy of spinal screw instrumentation using a hybrid operating room (OR) and quantify the related radiation exposure. This retrospective study included 33 cases of complex spine fusion surgeries that were conducted using a hybrid OR with a flat panel detector (FPD) angiography system. Twelve cases (36.4%) were cervical, and 21 (63.6%) were thoracolumbar. The average number of spine fusion levels was 3 and 4.8, respectively, at the cervical and thoracolumbar spine levels. A FPD angiography system was used for intraoperative cone-beam computed tomography (CBCT) to obtain multi-slice spine images. All operations were conducted under optimized radiation shielding. Entrance surface doses (ESDs) and exposure times were recorded in all cases. A total of 313 screws were placed. Satisfactory screw insertion could be achieved in all cases with safe screw placement in 97.4% and acceptable placement in 2.6%. None of the cases showed any significant anatomical violation by the screws. The radiation exposure to the patients was absolutely consistent with the desired ESD value, and that to the surgeons, under the annual dose limit. These results suggest that the hybrid OR with a FPD angiography system is helpful to achieve safe and precise spinal fusion surgery, especially in complex cases.

Dosimetric assessment of the exposure of radiotherapy patients due to cone-beam CT procedures.

Cone-beam computed tomography (CBCT) is widely used for pre-treatment verification and patient setup in image-guided radiation therapy (IGRT). CBCT imaging is employed daily and several times per patient, resulting in potentially high cumulative imaging doses to healthy tissues that surround exposed target organs. Computed tomography dose index (CTDI) is the parameter used by CBCT equipment as indication of the radiation output to patients. This study aimed to increase the knowledge on the relation between CBCT organ doses and weighted CTDI (CTDIW) for a thorax scanning protocol. A CBCT system was modelled using the Monte Carlo (MC) radiation transport program MCNPX2.7.0. Simulation results were validated against half-value layer (HVL), axial beam profile, patient skin dose (PSD) and CTDI measurements. For organ dose calculations, a male voxel phantom ("Golem") was implemented with the CBCT scanner computational model. After a successful MC model validation with measurements, a systematic comparison was performed between organ doses (and their distribution) and CTDI dosimetry concepts [CTDIW and cumulative dose quantities f100(150) and [Formula: see text]]. The results obtained show that CBCT organ doses vary between 1.2 ± 0.1 mGy and 3.3 ± 0.2 mGy for organs located within the primary beam. It was also verified that CTDIW allows prediction of absorbed doses to tissues at distances of about 5 cm from the isocentre of the CBCT system, whereas f100(150) allows prediction of organ doses at distances of about 10 cm from the isocentre, independently from its location. This study demonstrates that these dosimetric concepts are suitable methods that easily allow a good approximation of the additional CBCT imaging doses during a typical lung cancer IGRT treatment.

Intra- and inter-fraction uncertainties during IGRT for Wilms' tumor.

BACKGROUND AND PURPOSE: To assess intra- and inter-fraction motion uncertainties, due to displacements of the tumor bed (TB) and organs at risk (OAR), as well as intra- and inter-fraction patient set-up uncertainties, due to positioning variations, during image-guided radiation therapy (IGRT) in children with Wilms' tumor. MATERIAL AND METHODS: Four-dimensional computed tomography (4D-CT) and daily pre- and post-treatment cone-beam CT (CBCT)-scans of 15 patients (average 4, range 1-8 years) undergoing flank irradiation after nephrectomy were analyzed. TB (marked by four surgical clips) and OAR motion uncertainties were quantified by displacements of the center of mass in all orthogonal directions. Translational and rotational bone off-sets were recorded for patient set-up uncertainties assessment in all orthogonal directions. The average results, systematic and random errors were computed. RESULTS: Average intra- and inter-fraction motion uncertainties were ≤1.1 mm (range: [-6.9;7.9] mm) for the TB and ≤3.2 mm (range: [-9.1;9.6] mm) for the OAR. Average intra- and inter-fraction patient set-up uncertainties were ≤0.1 mm (range: [-3.3;4.8] mm) and ≤0.9° (range: [0.0;2.8°]). Both motion and patient set-up uncertainties were larger for the cranio-caudal direction. Calculated systematic and random errors were ≤2.4 mm for the motion uncertainties and ≤0.8 mm/0.7° for the patient set-up uncertainties. CONCLUSIONS: Average motion and patient set-up uncertainties during radiotherapy treatment were found to be limited. However, uncertainties were larger for the cranio-caudal direction and outliers were found in all orthogonal directions. When having available 4D-CT and CBCT information, the use of patient-specific and anisotropic safety margin expansions is advised for both target volume and OAR.

Image Fusion and 3-Dimensional Roadmapping in Endovascular Surgery.

Practitioners of endovascular surgery have historically used 2-dimensional (2D) intraoperative fluoroscopic imaging, with intravascular contrast opacification, to treat complex 3-dimensional (3D) pathology. Recently, major technical developments in intraoperative imaging have made image fusion techniques possible, the creation of a 3D patient-specific vascular roadmap based on preoperative imaging which aligns with intraoperative fluoroscopy, with many potential benefits. First, a 3D model is segmented from preoperative imaging, typically a computed tomography scan. The model is then used to plan for the procedure, with placement of specific markers and storing of C-arm angles that will be used for intraoperative guidance. At the time of the procedure, an intraoperative cone beam computed tomography is performed, and the 3D model is registered to the patient's on-table anatomy. Finally, the system is used for live guidance in which the 3D model is codisplayed with overlying fluoroscopic images. There are many applications for image fusion in endovascular surgery. We have found it to be particularly useful for endovascular aneurysm repair (EVAR), complex EVAR, thoracic EVAR, carotid stenting, and for type 2 endoleaks. Image fusion has been shown in various settings to lead to decreased radiation dose, less iodinated contrast use, and shorter procedure times. In the future, fusion models may be able to account for vessel deformation caused by the introduction of stiff wires and devices, and the user-dependent steps may become more automated. In its current form, image fusion has already proven itself to be an essential component in the planning and success of complex endovascular procedures.

Understanding and communicating radiation dose and risk from cone beam computed tomography in dentistry.

With the increased use of 3-dimensional dental imaging and cone beam computed tomography in dentistry, dental practitioners should understand and effectively communicate the associated radiation doses and risks to patients. This article will explain dose and risk of cone beam computed tomography technology, drawing on 3 decades of experience in communicating human health risk to the public from radiation exposure in the environment. This report provides examples of dose and risk metrics and comparisons to help providers understand the risk to their patients and to effectively communicate that risk. In the clinical setting, providers can use the guidelines outlined in this report for responsible delivery of dose using cone beam computed tomography. In addition, the metrics and comparisons provided here can be shared with patients to aid in communicating pertinent information about dose and risk.