CT Volumetric Assessment of Pulmonary Neoplasms after Radiofrequency Ablation: When to Consider a Second Intervention?

PurposeTo determine the minimal follow-up time point to predict therapeutic response to radiofrequency (RF) ablation of lung tumors.Materials and MethodsA retrospective study design was approved by the institutional review board. From January 2008 to January 2010, 78 patients (46 men and 32 women; mean age, 58.9 y) underwent computed tomography (CT)–guided percutaneous RF ablation of pulmonary malignancies. A single RF multitined electrode was used to treat 100 index tumors, 6 primary lesions, and 94 metastatic lesions. CT volumetric measurements of ablated tumors were made before ablation and 24 hours, 3–6 weeks, 3 months, 6 months, 9 months, and 12 months after ablation. An unpaired t test and Spearman rank correlation coefficient were used to analyze the volumetric changes.ResultsComplete successful ablation was achieved in 80% of index tumors. The mean time to detection of tumor residue or recurrence tumor residue or recurrence was 6.7 months after ablation. In successfully ablated lesions, the mean volume before ablation was 1.81 cm³ (standard deviation [SD], 1.71); in failed ablation lesions, the mean volume before ablation was 2.58 cm³ (SD, 2.8) (P = .42). The earliest statistically significant follow-up time point that showed a difference in the volumetric measurements of failed and successful ablations as well as the earliest significant correlation with the 12-month point was 3 months (P = .025, Spearman R = 0.72). Secondary tumor control after repeat ablation was statistically significant for lesions ablated at a 3-month interval (four out of five lesions) (P = .04).ConclusionsCT volumetric assessment of ablated tumors revealed that 3 months was the earliest time point that may determine the response of a pulmonary ablation or repeat intervention.     

Relationship of Antenna Work and Ablation Cavity Volume Following Percutaneous Microwave Ablation of Hepatic Tumors

PurposeTo formulate a statistical model relating ablation time, power, and work with posttreatment cavity volume following percutaneous microwave ablation of hepatic tumors in vivo.Materials and MethodsA retrospective review (October 2015 to October 2018) yielded 122 hepatic tumors treated with microwave ablation. Ablation cavity dimensions were measured at 1-month follow-up examination and calculated using an ellipsoid volume formula. The antenna manufacturer (Neuwave Medical, Madison, Wisconsin) provided the activation time and energy used to calculate the antenna work. Generalized estimating equations with ordinary least-squares regression models were obtained to relate tumor volume with cumulative antenna work. Coefficient of determination (R²) and mean square error were used as statistical measures of model prediction performance.ResultsThere is a logarithmic relationship between postablation cavity volume (cm³) and cumulative work (kJ), represented by the formula: log₁₀ cm³ = ?0.4583 + 0.9887 × cumulative work (log10 kJ) (R² = 0.41, mean square error, 0.102). Ablation volumes were predicted as a function of antenna work, calculated using an antilog transformation. When a single antenna was used, ablation cavity volume was predicted using a generalized estimating equation ordinary least-squares regression model of power and time: log₁₀cm³= ?0.0546 + 0.0485 × total time (min) + 0.0107 × power (W) (R² = 0.30; mean square error, 0.106). Using this model, a nomogram was developed to predict the postablation cavity volume based on total activation time and target power.ConclusionThere is a logarithmic relationship between the ablation work and posttreatment ablation cavity volume, which can be expressed in a nomogram when using a single probe.     

Computed Tomography Evaluation of In Vivo Pulmonary Cryoablation Zone Sizes

PurposeTo evaluate ablation zone sizes in patients undergoing pulmonary tumor cryoablation with 14-gauge cryoablation probes.Materials and MethodsA single-center retrospective analysis of all consecutive patients who underwent cryoablation of pulmonary tumors with 1 or more 14-gauge probes (August 2017 to June 2020) was performed. Intraprocedural and 1–2-month postprocedural chest computed tomography (CT) scans were evaluated to characterize pulmonary lesions, ice balls, and ablation zones. Single-probe 14-gauge ablation zone volumes were compared with manufacturer reference isotherms and single- and 2-probe ablation zones from a prior investigation of 17-gauge probes. Overall survival and local recurrence–free survival were calculated to 3 years.ResultsForty-seven pulmonary malignancies in 42 patients (women, 50%; mean age, 75.2 years ± 11.5) underwent cryoablation with 1 (n = 35), 2 (n = 10), or 3 (n = 2) cryoablation probes. One- to 2-month follow-up CT images were available for 30 of the 42 patients. The mean cryoablation zone volumes at 1–2 months when 1 (n = 21), 2 (n = 8), and 3 (n = 1) probes were used were 5.0 cm³ ± 2.3, 37.5 cm³ ± 20.5, and 28.4 cm³, respectively. The mean single-probe follow-up ablation zone volume was larger than that previously reported for 17-gauge probes (3.0 cm³ ± 0.3) (P < .001) but smaller than manufacturer-reported isotherms (11.6 cm³ for ?40 °C isotherm) and the 2-probe ablation zone volume with 17-gauge devices (12.9 cm³ ± 2.4) (for all, P < 001). The 3-year overall survival and local recurrence–free survival were 69% (95% confidence interval [CI], 53%–89%) and 87% (95% CI, 74%–100%), respectively.ConclusionsFourteen-gauge probes generate larger ablation volumes than those generated by 17-gauge probes. Manufacturer-reported isotherms are significantly larger than actual cryoablation zones. Cryoablation can attain low rates of local recurrence.     

Evaluation of Outcomes following Radiofrequency Ablation for Treatment of Parotid Tail Warthin Tumors

PurposeTo evaluate efficacy and safety of radiofrequency (RF) ablation for parotid Warthin tumor.Materials and MethodsFrom September 2016 to August 2017, 7 consecutive patients with biopsy-proven parotid Warthin tumors who did not undergo surgery presented with symptoms or cosmetic concerns and underwent US-guided percutaneous RF ablation treatment. RF ablation procedures were performed using the moving shot technique. US, contrast-enhanced CT, or MR imaging was performed 6–12 months after each procedure. Complications and cosmetic scale improvement after RF ablation were also evaluated.ResultsThere was a significant reduction in mean tumor volume from 14.6 cm³ ± 13.1 (range, 1.9–35.5 cm³) to 0.8 cm³ ± 0.5 (range, 0.2–1.54 cm³) and a mean cosmetic scale improvement (from 4 to 1) on imaging studies 6–12 months after RF ablation compared with before RF ablation (P < .05). Volume reduction ratios at 1–2 months, 5–6 months, and 10–12 months after RF ablation were 51.2% ± 18.1%, 87.8% ± 10.6%, and 94.3% ± 2.0%. There was no facial nerve injury. One patient with parotitis and hematoma recovered in 1 week.ConclusionsRF ablation using the moving shot technique could be an effective and safe alternative treatment for parotid tail Warthin tumors in patients unsuitable for or unwilling to undergo surgical resection.     

Percutaneous Microwave Ablation of Hepatic Tumors: Prospective Evaluation of Postablation Syndrome and Postprocedural Pain

PurposeTo prospectively investigate the frequency and severity of postablation syndrome (PAS) and postprocedural pain in a cohort of patients undergoing hepatic microwave ablation.Materials and MethodsFrom March 2009 to November 2011, 54 consecutive patients undergoing microwave ablation for liver tumors were enrolled. A questionnaire was administered to investigate PAS and pain at 1, 7, and 40 days after ablation. Four patients did not complete all three questionnaires and were excluded from the analysis. Additionally, laboratory tests with results known to significantly increase or decrease after ablation were performed, and ablation parameters were recorded. Potential predictors of PAS and pain at 1 and 7 days were evaluated by a logistic regression model.ResultsFifty patients underwent a single microwave ablation session, 33 for hepatocellular carcinoma (HCC) and 17 for liver metastasis. Median ablation volumes on computed tomography were 31 cm³ for HCC and 42 cm³ for metastasis. Sixty percent of patients experienced PAS in the first week. Aspartate aminotransferase (AST) levels after ablation were significantly associated with PAS during postprocedure days 1–7. Median visual analog scale scores for pain at the puncture site were 1 and 0.24 at 1 and 7 days, respectively. The risk of having at least moderate pain in the first week was significantly related to ablation volume and time and postablation increase in AST level.ConclusionsThe incidence and severity of PAS with hepatic microwave ablation is similar to that reported for radiofrequency ablation, with the best predictive factor being postablation AST level elevation. Postablation pain was best predicted by total ablation volume and AST level.     

Preliminary Study of Microwave Ablation for Multifocal Papillary Thyroid Microcarcinoma in Nonoperative Candidates

PurposeTo study the feasibility, safety, and effectiveness of microwave ablation (MWA) in patients with multifocal papillary thyroid microcarcinoma (PTMC).Materials and MethodsThis retrospective study included patients who underwent MWA for multifocal PTMC (number of nodules ≤3). A total of 44 patients were included, and the mean age was 43 years (SD ± 11). After ablation, progression-free survival (PFS) at 6, 12, 24, 36, and 48 months; disease progression; change in tumor size and volume; tumor disappearance rate; and adverse events (AEs) were assessed, and the feasibility, safety, and effectiveness of MWA for PTMC were evaluated on the basis of statistical analysis.ResultsThe median follow-up period was 18 months (interquartile range, 12–33 months). The PFS rates at 6, 12, 24, 36, and 48 months were 100.0%, 96.4%, 96.4%, 70.3%, and 52.7%, respectively. The disease progression rate was 11.4% (5 of 44 patients). The maximum diameter (MD) and volume of the ablation zone were larger at the 3-month follow-up than before ablation (median MD, 13.0 vs 7.0 mm; P < .001; median volume, 503.8 vs 113.0 mm³; P < .001). Subsequently, the tumors exhibited a reduction in both size and volume after 18 months (median MD, 4.0 vs 7.0 mm; P = .04; median volume, 12.6 vs 113.0 mm³; P = .055). At the end of the follow-up period, the complete response rate was 59% (26 of 44 patients). The overall AE rate was 6.8%.ConclusionsMWA is a feasible treatment for PTMC (number of nodules ≤3), and this study preliminarily demonstrated the safety and effectiveness of this technique.     

Percutaneous Radiofrequency Ablation with Internally Cooled versus Internally Cooled Wet Electrodes for Small Subphrenic Hepatocellular Carcinomas

PurposeTo compare retrospectively technical effectiveness and complications after radiofrequency (RF) ablation with internally cooled wet (ICW) electrodes versus conventional internally cooled (IC) electrodes in patients with small (≤3 cm) subphrenic hepatocellular carcinomas (HCCs).Materials and MethodsFrom March 2008 to January 2012, 165 patients, each with a single small subphrenic HCC, were treated with RF ablation using IC (n = 81) or ICW (n = 84) electrodes.ResultsAfter initial RF ablation, technical success was achieved in 88% of patients treated with IC electrodes and 91% of patients treated with ICW electrodes (P = .623). At 1 month, technical effectiveness was achieved in 93% and 99% (P = .061). Mean ablation volume was significantly greater in patients treated with ICW electrodes compared with patients treated with IC electrodes, using 2-cm (14.5 cm³ vs 6.2 cm³; P = .001) and 3-cm (32.7 cm³ vs 15.2 cm³; P <.001) exposed tips. The 6-month and 1-, 2-, and 4-year local tumor progression rates were significantly lower after RF ablation with ICW electrodes (5%, 13%, 15%, and 26%) compared with IC electrodes (11%, 24%, 32%, and 35%; P = .044). Major complications occurred in 6% of patients treated with IC electrodes and 2% of patients treated with ICW electrodes.ConclusionsIn the treatment of small subphrenic HCCs, percutaneous RF ablation using ICW electrodes results in larger ablation zones and lower rates of local tumor progression than RF ablation using conventional IC electrodes.     

Quantitative Assessment of Lipiodol Deposition after Chemoembolization: Comparison between Cone-Beam CT and Multidetector CT

PurposeTo evaluate the ability of cone-beam computed tomography (CBCT) performed directly after transarterial chemoembolization to assess ethiodized oil (Lipiodol) deposition in hepatocellular carcinoma (HCC) and compare it with unenhanced multidetector computed tomography (CT).Materials and MethodsConventional transarterial chemoembolization was used to treat 15 patients with HCC, and CBCT was performed to assess Lipiodol deposition directly after transarterial chemoembolization. Unenhanced multidetector CT was performed 24 hours after transarterial chemoembolization. Four patients were excluded because the margin of tumor or area of Lipiodol deposition was unclear. The image enhancement density of the entire tumor and liver parenchyma was measured by ImageJ software, and tumor-to-liver contrast (TLC) was calculated. In addition, volumetric measurement of tumor and Lipiodol was performed by semiautomatic three-dimensional volume segmentation and compared using linear regression to evaluate consistency between the two imaging modalities.ResultsThe mean value of TLC on CBCT was not significantly different from TLC on multidetector CT (337.7 HU ± 233.5 vs 283.0 HU ± 152.1, P = .103).The average volume of the whole tumor and of only the regions with Lipiodol deposition and the calculated average percentage of Lipiodol retention on CBCT were not significantly different compared with multidetector CT (tumor volume, 9.6 cm³ ± 11.8 vs 10.8 cm³ ± 14.2, P = .142; Lipiodol volume, 6.3 cm³ ± 7.7 vs 7.0 cm³ ± 8.1, P = .214; percentage of Lipiodol retention, 68.9% ± 24.0% vs 72.2% ± 23.1%, P = .578). Additionally, there was a high correlation in the volume of tumor and Lipiodol between CBCT and multidetector CT (R² = 0.919 and 0.903).ConclusionsThe quantitative image enhancement and volume analyses demonstrate that CBCT is similar to multidetector CT in assessing Lipiodol deposition in HCC after transarterial chemoembolization.     

Adjuvant Thermal Accelerant Gel Use Increases Microwave Ablation Zone Temperature in Porcine Liver as Measured by MR Thermometry

PurposeTo determine the effects of a thermal accelerant gel on temperature parameters during microwave liver ablation.Materials and MethodsSixteen consecutive liver ablations were performed in 5 domestic swine under general anesthesia with (n = 8) and without (n = 8) administration of thermal accelerant gel. Ablation zone temperature was assessed by real-time MR thermometry, measured as maximum temperature (T_max) and the volume of tissue ≥ 60°C (V₆₀). Tissue heating rate, ablation zone shape, and thermal energy deposition using the temperature degree-minutes at 43°C (TDM43) index were also measured. Differences between groups were analyzed using generalized mixed modeling with significance set at P = .05.ResultsMean peak ablation zone temperature was significantly greater with thermal accelerant use (mean T_max, thermal accelerant: 120.0°C, 95% confidence interval [CI] 113.0°C–126.9°C; mean T_max, control: 80.3°C, 95% CI 72.7°C–88.0°C; P < .001), and a significantly larger volume of liver tissue achieved or exceeded 60°C when thermal accelerant was administered (mean V₆₀, thermal accelerant: 22.2 cm³; mean V₆₀, control: 15.9 cm³; P < .001). Significantly greater thermal energy deposition was observed during ablations performed with accelerant (mean TDM43, thermal accelerant: 198.4 min, 95% CI 170.7–230.6 min; mean TDM43, control: 82.8 min, 95% CI 80.5–85.1 min; P < .0001). The rate of tissue heating was significantly greater with thermal accelerant use (thermal accelerant: 5.8 min ± 0.4; control: 10.0 min; P < .001), and accelerant gel ablations demonstrated a more spherical temperature distribution (P = .002).ConclusionsThermal accelerant use is associated with higher microwave ablation zone temperatures, greater thermal energy deposition, and faster and more spherical tissue heating compared with control ablations.     

Coil Embolization of the Splenic Artery: Impact on Splenic Volume

PurposeTo determine the impact of coil embolization of the splenic artery on splenic volume based on computed tomography (CT) imaging.Materials and MethodsSplenic artery embolization (SAE) was performed in 148 consecutive patients over an 8-year period in an institutional review board–approved retrospective study. Of these, 60 patients (36 men; mean age, 49 y) had undergone contrast-enhanced CT before and after SAE with a mean time interval of 355 days. Pre- and postembolization splenic volumes were calculated with volume-rendering software. Presence of Howell–Jolly bodies was ascertained on laboratory tests. A trauma control group consisted of 39 patients with splenic laceration and follow-up CT but no splenic intervention.ResultsSAE in trauma patients resulted in an insignificant decrease in mean spleen size from 224 cm³ to 190 cm³ (P = .222). However, postembolization splenic volume was significantly smaller than follow-up volume in the trauma control group (353 cm³; P < .001). In nontrauma patients, the mean splenic volume decreased from 474 cm³ to 399 cm³ after SAE (P = .068). Multivariable analysis revealed that coil pack location was the only factor significantly affecting resultant splenic volume (P = .016). For trauma and nontrauma patients, distal embolization resulted in significant splenic volume loss (P = .034 and P = .013), whereas proximal embolization did not. No patients had persistent circulating Howell–Jolly bodies after SAE. No patients required repeat embolization or splenectomy.ConclusionsCoil embolization of the splenic artery resulted in a modest but significant decrease in splenic volume when performed distally; proximal embolization resulted in an insignificant volume change.     

Percutaneous Microwave Ablation of Renal Angiomyolipomas

Purpose

To evaluate the safety and efficacy of US-guided percutaneous microwave (MW) ablation in the treatment of renal angiomyolipoma (AML).

Materials and Methods

From January 2011 to April 2014, seven patients (5 females and 2 males; mean age 51.4) with 11 renal AMLs (9 sporadic type and 2 tuberous sclerosis associated) with a mean size of 3.4 ± 0.7 cm (range 2.4–4.9 cm) were treated with high-powered, gas-cooled percutaneous MW ablation under US guidance. Tumoral diameter, volume, and CT/MR enhancement were measured on pre-treatment, immediate post-ablation, and delayed post-ablation imaging. Clinical symptoms and creatinine were assessed on follow-up visits.

Results

All ablations were technically successful and no major complications were encountered. Mean ablation parameters were ablation power of 65 W (range 60–70 W), using 456 mL of hydrodissection fluid per patient, over 4.7 min (range 3–8 min). Immediate post-ablation imaging demonstrated mean tumor diameter and volume decreases of 1.8 % (3.4–3.3 cm) and 1.7 % (27.5–26.3 cm³), respectively. Delayed imaging follow-up obtained at a mean interval of 23.1 months (median 17.6; range 9–47) demonstrated mean tumor diameter and volume decreases of 29 % (3.4–2.4 cm) and 47 % (27.5–12.1 cm³), respectively. Tumoral enhancement decreased on immediate post-procedure and delayed imaging by CT/MR parameters, indicating decreased tumor vascularity. No patients required additional intervention and no patients experienced spontaneous bleeding post-ablation.

Conclusion

Our early experience with high-powered, gas-cooled percutaneous MW ablation demonstrates it to be a safe and effective modality to devascularize and decrease the size of renal AMLs.

     

Characterization of In Vivo Ablation Zones Following Percutaneous Microwave Ablation of the Liver with Two Commercially Available Devices: Are Manufacturer Published Reference Values Useful?

PurposeTo analyze in vivo ablation properties of microwave ablation antennae in tumor-bearing human livers by performing retrospective analysis of ablation zones following treatment with two microwave ablation systems.Materials and MethodsPercutaneous microwave ablations performed in the liver between February 2011 and February 2013 with use of the AMICA and Certus PR ablation antennae were included. Immediate postablation computed tomography images were evaluated retrospectively for ablation length, diameter, and volume. Ablation length, diameter, and volume indices were calculated and compared between in vivo results and references provided from each device manufacturer. The two microwave antenna models were then also compared versus each other.ResultsTwenty-five ablations were performed in 20 patients with the AMICA antenna, and 11 ablations were performed in eight patients with the Certus PR antenna. The AMICA and Certus PR antennae showed significant differences in ablation length (P = .013 and P = .009), diameter (P = .001 and P = .009), and volume (P = .003 and P = .009). The AMICA ablation indices were significantly higher than the Certus PR ablation indices in length (P = .026) and volume (P = .002), but there was no significant difference in ablation diameter indices (P = .110).ConclusionsIn vivo ablation indices of human tumors are significantly smaller than reference ex vivo ablation indices, and there are significant differences in ablation indices and sphericity between devices.     

Microwave Ablation in Porcine Livers Applying 5-minute Protocols: Influence of Deployed Energy on Extent and Shape of Coagulation

PurposeTo evaluate the influence of deployed energy on extent and shape of microwave (MW)-induced coagulation in porcine livers applying 5-minute protocols.Materials and MethodsMW ablations (n = 25) were performed in ex vivo porcine livers (n = 8). Ablation time was 5 minutes. Five study groups were defined, each with different power output: I, 20 W (n = 5); II, 40 W (n = 5); III, 60 W (n = 5); IV, 80 W (n = 5); and V, 105 W (n = 5). Extent and shape of white coagulation was evaluated macroscopically, including short diameter, volume, front margin, coagulation center (distance between center of short diameter of coagulation and applicator tip), and ellipticity index (short diameter/long diameter). Deployed energy was also analyzed.ResultsShort diameter and volume were significantly different (P<.001 and P<.001) between the groups: I, 23.0 mm and 11.1 cm³; II, 12.4 mm and 12.4 cm³; III, 27.0 mm and 17.6 cm³; IV, 31.0 mm and 29.2 cm³; and V, 35.0 mm and 42.3 cm³. Front margin and coagulation center were also significantly different (P<.05 and P<.001): I, 6.0 mm and 13.0 mm; II, 8.0 mm and 11.0 mm; III, 8.0 mm and 14.0 mm; IV, 8.0 mm and 18.0 mm; and V, 10.0 mm and 19.0 mm. Ellipticity index was not significantly different. Deployed energy was significantly different (P<.001): I, 5.7 kJ; II, 11.0 kJ; III, 15.5 kJ; IV, 21.6 kJ; and V, 26.6 kJ.ConclusionsExtent, but not shape, of MW-induced coagulation depends on the deployed energy. Applying the protocols described in this study, significantly different coagulation volumes can be created with an ablation time of 5 minutes but different power output.     

Impact on renal function of percutaneous thermal ablation of renal masses in patients with preexisting chronic kidney disease

PurposeTo examine the effect of percutaneous thermal ablation of renal masses on renal function among patients with baseline chronic kidney disease (CKD).Materials And MethodsPatients with baseline CKD (initial glomerular filtration rate [GFR] < 60 mL/min/1.73 m²) who underwent percutaneous cryoablation or radiofrequency (RF) ablation of renal masses were reviewed.ResultsA total of 48 patients with a GRF of 60 mL/min/1.73 m² or lower were treated with renal cryoablation or RF ablation and had follow-up GFR measurement 1 month afterward. Mean patient age was 73 years (range, 47–89 y). Cryoablation was performed in 22 patients and RF ablation was performed in 26. Mean tumor diameter was 3.4 cm (range, 0.9–10.2 cm). Mean overall GFRs were 39.8 mL/min/1.73 m² at baseline and 39.7 mL/min/1.73 m² at 1 month after ablation (P = .85). A total of 38 patients had 1-year follow-up GFR measurement (cryoablation, n = 18; RF ablation, n = 20), and their mean GFR was 40.9 mL/min/1.73 m² ± 11.4 (SD), compared with a preablation GFR of 41.2 mL/min/1.73 m²(P = .79). In the cryoablation group, mean GFRs at 1 month and 1 year were 41.4 mL/min/1.73 m² and 44.4 mL/min/1.73 m², compared with respective baseline GFRs of 41.1 mL/min/1.73 m² and 42.1 mL/min/1.73 m² (P = .75 and P = .19, respectively). In the RF ablation group, mean GFRs at 1 month and 1 year were 38.2 mL/min/1.73 m² and 37.8 mL/min/1.73 m², compared with respective baseline GFRs of 38.7 mL/min/1.73 m² and 40.4 mL/min/1.73 m² (P = .58 and P = .09, respectively).ConclusionsIndependent of ablation modality, percutaneous renal mass ablation does not appear to affect renal function among patients with CKD.     

A Single-Center 10-Year Retrospective Analysis of Cryoablation for the Management of Desmoid Tumors

PurposeTo determine the efficacy and safety of cryoablation in patients with desmoid tumors (DTs) retrospectively over a 10-year period at a single institution.Materials and MethodsBetween February 25, 2010, and February 25, 2020, 25 patients (age, 12–80 years) with 26 lesions (mean preprocedural tumor volume was 237 cm³) were treated over 44 cryoablation procedures. Eleven patients were treated with first-line therapy. Fourteen patients had previous medical therapy, radiotherapy, and/or surgery. Subsequent clinical follow-up, imaging outcomes, and safety were analyzed for technical success, change in total lesion volume (TLV) and viable tumor volume (VTV), modified response evaluation criteria in solid tumors (mRECIST), progression-free survival (PFS) for tumor progression and symptom recurrence, symptom improvement, and procedure-related complications. Symptomatic improvement was defined as documentation of relief of pain (partial or complete) and/or functional impairment.ResultsAll procedures were technically successful. At 7–12 months, median changes in TLV and VTV were −6.7% (P = .809) and −43.7% (P = .01), respectively. At 10–12 months, the mRECIST responses were complete response, 0%; partial response, 61.5% (8/13); stable disease, 30.8% (4/13); and progressive disease, 7.7% (1/13). The median PFS for tumor progression and symptom recurrence were not reached, with a median follow-up of 15.3 and 21.0 months, respectively. Symptomatic relief (partial or complete) was achieved in 96.9% (32/33) of patients. One major complication was noted (2.4%).ConclusionsIn this retrospectively identified cohort, cryoablation was effective and safe for the local control of extra-abdominal DTs in short-term follow-up.     

Radiofrequency Ablation,Cryoablation, and Microwave Ablation for T1a Renal Cell Carcinoma: A Comparative Evaluation of Therapeutic and Renal Function Outcomes

PurposeTo compare the therapeutic and renal function outcomes of radiofrequency (RF) ablation, cryoablation, and microwave (MW) ablation for treatment of T1a renal cell carcinoma (RCC).Materials and MethodsA retrospective assessment of 297 patients (mean age 72 years range 24–90 years) with biopsy-proven RCC treated with image-guided percutaneous thermal ablation was performed between October 2006 and December 2016. Mean tumor size was 2.4 cm; mean radius, exophytic/endophytic properties, nearness of tumor to collecting system or sinus, anterior/posterior, hilar tumor touching the main renal artery or vein, and location relative to polar lines; Preoperative Aspects and Dimensions Used for an Anatomical; and c-centrality scores were 6.0, 7.0, and 2.8, respectively. Assessments of adverse events, treatment efficacy, and therapeutic outcomes were performed among RF ablation, cryoablation, and MW ablation. The 2-year disease-free, metastatic-free, and cancer-specific survival rates were tabulated. Estimated glomerular filtration rate was used to assess for treatment related changes in renal function.ResultsA total of 297 T1aN0M0 biopsy-proven RCCs measuring 1.2–3.9 cm were treated with computed tomography–guided RF ablation (n = 244, 82%), cryoablation (n = 26, 9%), and MW ablation (n = 27, 9%). There were no significant differences in patient demographics among the 3 groups (P = .09). Technical success rates were similar among the 3 treatments (P = .33). Primary efficacy at 1 month postablation was more likely to be achieved with RF ablation and MW ablation than with cryoablation. At 2 years’ follow-up, there was no local recurrence, metastatic progression, or RCC-related death observed in the 3 groups. There was no significant change in estimated glomerular filtration rate among the 3 ablation groups compared with baseline at 2-year follow-up (P = .71).ConclusionRF ablation, cryoablation, and MW ablation are equivalent at 2 years for treatment of T1a RCC for therapeutic outcome, stability of renal function, and low adverse event rate.     

Value of 18F-FDG PET/MR Imaging in the Early Evaluation of Treatment Response following Radiofrequency Ablation of Liver Cancer in a Rabbit Model

PurposeTo test the hypothesis that ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography (PET) and magnetic resonance (MR) imaging can detect early residual tumor following radiofrequency (RF) ablation of liver cancer using a VX2 tumor model.Materials and MethodsTwenty-four rabbits with VX2 liver tumors were randomly divided into 3 groups (n = 8/group): Group 1 without RF ablation treatment, Group 2 with complete ablation, and Group 3 with partial ablation. An ¹⁸F-FDG PET/MR imaging scan was obtained within 2 hours after RF ablation. The maximum standardized uptake values (SUV) of the nontreated liver tumor, benign periablational enhancement (BPE), residual tumor, ablated tumor, and adjacent liver parenchyma and mean SUV of the normal liver were measured. The ratios of maximum SUV for these targets to the mean SUV of the normal liver (TNR) were calculated and compared.ResultsThe mean TNR of the nontreated liver tumors in Group 1 was significantly greater than that of the adjacent liver parenchyma (8.68 ± 0.71 vs 1.89 ± 0.26, P < .001). In Group 2, the mean TNR of BPE was significantly greater than that of the adjacent liver parenchyma (2.85 ± 0.20 vs 1.86 ± 0.25, P < .001). In Group 3, the mean TNR of the residual tumor was significantly greater than that of BPE (8.64 ± 0.59 vs 2.78 ± 0.23, P < .001), which was significantly greater than that of completely ablated tumor (2.78 ± 0.23 vs 0.50 ± 0.06, P < .001).Conclusions¹⁸F-FDG PET/MR imaging may serve as a promising imaging tool for the early detection of viable residual tumors due to incomplete tumor ablation.     

Dual-Applicator MR Imaging–Guided Microwave Ablation with Real-Time MR Thermometry: Phantom and Porcine Tissue Model Experiments

PurposeTo investigate the effect of simultaneous use of dual applicators on the image quality of real-time magnetic resonance (MR) thermometry and to characterize the dual-applicator treatment zone pattern during MR imaging–guided microwave ablation (MWA).Materials and MethodsMWA experiments were performed on a 1.5-T MR scanner with 2 commercial microwave systems (902–928 MHz). Phantom experiments were first performed to evaluate the effect of dual-applicator MWA on the image quality of MR. Then, porcine tissue model experiments were conducted with real-time MR thermometry using either a single applicator or dual applicators inserted 2.6, 3.6, and 4.6 cm apart. Fiberoptic thermal probes were used to measure the temperature changes at the tissue surface.ResultsSimultaneous use of dual applicators resulted in a decrease in the relative signal-to-noise ratio (SNR) in the MR thermometry images to 55% ± 2.9% when compared with that of a single applicator (86.2% ± 2.0%). Despite the lower SNR, the temperature and ablation zone maps were of adequate quality to allow visualization of the ablation zone(s). The extents of increase in the temperature at the tissue surface using dual applicators (19.7 °C ± 2.6 °C) and a single applicator (18.2 °C ± 3.3 °C) were not significantly different (P = .40). Treatment zones were significantly larger (P < .05) in dual-applicator ablations (29.4 ± 0.4, 39.9 ± 0.6, and 42.6 ± 0.9 cm² with 2.6-, 3.6-, and 4.6-cm spacing, respectively) at the end of the ablation procedure than in the single-applicator MWA (18.6 ± 0.9 cm²).ConclusionsMR imaging–guided dual-applicator MWA produced larger ablation zones while allowing adequate real-time MR thermometry image quality for monitoring the evolution of the treatment zone.     

Hypertensive Crisis during Microwave Ablation of Adrenal Neoplasms: A Retrospective Analysis of Predictive Factors

PurposeTo identify risk factors for hypertensive crisis (HC) during ultrasound-guided percutaneous microwave (MW) ablation of adrenal neoplasms.Materials and MethodsPatients who underwent MW ablation for adrenal tumors between April 2006 and November 2017 were retrospectively identified for this study (51 consecutive patients; 35 males, 16 females; mean age, 55 years; range, 15–85 years). A total of 77 MW ablation treatments were performed for 67 tumors (24 primary [9 pheochromocytomas, 8 adenomas, and 7 cortical carcinomas]; and 43 metastases [22 hepatocellular carcinoma, 8 renal cell carcinoma, 5 non-small cell lung cancer, 4 colorectal cancer, 3 liposarcoma, and 1 malignant fibrous histiocytoma]). The mean diameter of the adrenal tumors was 4.6 cm (range, 1.2–16.2 cm). Information about patient demographics, imaging studies, pathology and laboratory results, procedure records, and clinical outcomes was retrieved and analyzed. Statistical analysis was then performed to determine potential risk factors for HC.ResultsOf the 77 MW ablation procedures, HC occurred in 13 (16.9%). A significantly higher risk of HC was observed in patients with pheochromocytoma (odds ratio [OR], 9.037; 95% confidence interval [CI], 1.731–47.172; P = .009), body mass index <24 kg/m² (OR, 5.167; 95% CI, 1.060–25.194; P = .042), dominant tumor size ≤4.5 cm (OR, 4.023; 95% CI, 1.011–16.005; P = .048), and pre-procedural systolic blood pressure ≥130 mmHg (OR, 0.242; 95% CI, 0.068–0.861; P = .029).ConclusionHC can occur during MW ablation in patients with either primary or metastatic adrenal tumors. Pheochromocytoma, body mass index, tumor size, and pre-procedural systolic blood pressure appear to be significant risk factors for the occurrence of HC.     

Higher percentage of positive biopsy cores and Gleason score are associated with a greater degree of prostate gland shrinkage after neoadjuvant cytoreductive therapy

PurposeTo determine whether adverse pathologic features, including tumor grade and percent positive biopsy (PPB) cores, predict for prostate size reduction after neoadjuvant cytoreductive therapy.Methods and MaterialsEighty-two consecutive patients who were diagnosed with prostate cancer by transperineal template–guided mapping biopsy (TTMB) received neoadjuvant cytoreductive therapy. The median number of biopsy cores was 59. Thirty patients received a leutinizing hormone–releasing hormone agonist and bicalutamide, whereas 52 patients received bicalutamide (50 mg daily) and dutasteride (0.5 mg daily). A transrectal ultrasound volumetric study of the prostate gland and ellipsoid volume determinations of the prostate gland and transition zone (TZ) were obtained immediately before TTMB and at 90 days (±7 days) after the initiation of neoadjuvant medical therapy. Univariate and multivariate regression analyses were performed to identify predictors of prostate gland and TZ volume reduction.ResultsAt TTMB, the mean prostate volumetric and ellipsoid volumes were 55.4 cm³ and 49.0 cm³, respectively. After neoadjuvant medical therapy, the mean volumetric and ellipsoid prostate volumes were 30.8 cm³ and 28.5 cm³, respectively. On average, the prostate volume decreased by 43.9% and 41.0% on volumetric and ellipsoid measurements, respectively. The TZ volume decreased from 19.8 cm³ to 10.1 cm³ (mean volume reduction of 47.7%). In multivariate analysis, prostate volume cytoreduction was most closely associated with PPB (p = 0.014), TTMB prostate volume (p = 0.01), and drug regimen (p = 0.001).ConclusionsThe degree of prostate volume cytoreduction was positively associated with higher Gleason score and PPBs. Greater reductions in prostate volume may be an indicator of more aggressive cancer.