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Thermal Ablation for Malignancy-Associated Pain
Colin J. McCarthy, MB, BCh, BAO, MRCSI, FFR (RCSI); Raul N. Uppot, MD; Christos Georgiades, MD, PhD
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KEY FACTS

  • Terminology

    • Preprocedure

      • Post Procedure

        • Outcomes

          • Procedure

            TERMINOLOGY

            • Definitions

              • Ablation: Direct application of chemical or thermal therapies to tumors for tissue destruction
              • Overall survival (OS): Length of time from either date of diagnosis or start of treatment for disease, such as cancer, to date of death of any cause
                • Usually expressed in median ± standard deviation
              • Cancer-specific survival (CSS): Length of time from either date of diagnosis or start of treatment for disease, such as cancer, to date of death from disease
                • Patients who die from causes unrelated to disease are not counted in this measurement
              • Progression-free survival: Length of time (from set point, usually treatment) that patient demonstrates no disease progression
              • Time to progression: Length of time (from set point, usually treatment) until patient shows disease progression
                • Mortalities are excluded
              • Disease-free survival (DFS): Length of time after treatment, until patient dies or shows evidence for recurrent disease
            • Ablation Modalities

              • Radiofrequency ablation (RFA)
                • Physics
                  • Relies on electrical conduction through tissue for heat generation
                  • Closed circuit necessary for conduction; body acts as resistor
                  • Direct radiofrequency heating
                    • Occurs within millimeters of applicator needle
                  • Thermal conduction
                    • Heat transfer more distally; therefore, good thermal conductivity crucial for large ablation
                    • Quick charring (dehydration) of tissue increases resistance, opens circuit, and limits ablation zone
                    • Slow, gradual "cooking" more effective than fast ablation
                  • Common current frequency of 400-500 kHz
                • Disadvantages
                  • Irregular ablation shape, depends on thermal conductivity of tissue
                  • Charring limits effectiveness
                  • Heat sink effect
                    • Flow of blood in nearby vessels cools tissue, limiting effectiveness
                  • Impedance (instead of temperature) regulating systems may lengthen total procedure time and increase ablation zone
                  • Grounding pads required for monopolar systems
                  • May require slow and lengthy treatment to effectively kill tumor
              • Microwave ablation (MWA)
                • Physics
                  • Relies on dielectric heating
                    • Alternating electromagnetic (EM) field applied to imperfect dielectric material (tissue); forces water molecules in tissue to oscillate
                    • Water molecules oscillate out of phase with EM field
                    • Frictional energy loss generates heat
                    • Higher water content = better heat absorption and conductivity = larger ablation zone
                  • Frequencies often 915 MHz or 2.45 GHz
                  • Relative permittivity: How well materials accept EM field (capacitance)
                    • Lower the permittivity, the less movement of energy from source dispersed through tissues
                    • Low relative permittivity: Bone, spleen
                    • High relative permittivity: Muscle, lung, liver
                  • Effective conductivity: How well tissue absorbs microwave energy
                    • Lower the conductivity, the higher thermal energy deposited locally, and the more effective ablation around antennae
                    • Low conductivity: Bone, lung, liver
                    • High conductivity: Muscle, blood, spleen
                • Advantages
                  • Ablation volume is more predictable, as it does not depend on thermal conductivity of tissue
                  • Can pass through and heat tissue at any temperature or water content
                  • Less susceptible to heat sink by producing larger areas of active heating
                  • Does not require grounding pads
              • Cryoablation
                • Physics
                  • Relies on Joules-Thomson effect
                    • Compressed gas circulates within double-barreled probe
                    • Gas released within probe results in sudden pressure drop
                    • Resultant temperature drop cools surrounding tissues
                  • Process consists of alternate freezing and thawing of tissue (commonly 10 minutes, 8 minutes, 10 minutes)
                  • Multifaceted cellular death mode: Cell membrane fracture, apoptosis, vessel thrombosis/ischemia
                  • Argon gas
                  • Each probe has characteristic isotherms (size and shape of surface with same temperature)
                  • Temperatures drop to ~ -150°C at probe
                  • Heat pump effect: Nearby vessels may increase temperature and limit ablation margin
                • Advantages
                  • Well tolerated (minimal pain)
                  • "Ice ball" readily visible with CT (US/MR) guidance
                    • Represents 0°C isotherm (not lethal)
                    • Lethal isotherm (-20°C) ~ 5 mm inside visible "ice ball"
                  • Operator can sculpt irregularly shaped ablation zone by altering orientation of multiple probes
                • Disadvantages
                  • More expensive, as multiple probes may be required
                  • System requires gas availability and storage

            PREPROCEDURE

            • Indications

              • Contraindications

                • Preprocedure Imaging

                  • Getting Started

                    PROCEDURE

                    • Patient Position/Location

                      • Baseline Imaging and Planning

                        • Probe Insertion/Positioning

                          • Added Maneuvers

                            • Intraprocedural Monitoring of Patient and Treatment

                              • Completion Imaging

                                • Recovery

                                  POST PROCEDURE

                                  • Things to Do

                                    OUTCOMES

                                    • Complications

                                      Selected References

                                      1. Burke CJ et al: Ultrasound-guided therapeutic injection and cryoablation of the medial plantar proper digital nerve (Joplin's Nerve): sonographic findings, technique, and clinical outcomes. Acad Radiol. ePub, 2019
                                      2. Ferrer-Mileo L et al: Efficacy of cryoablation to control cancer pain: a systematic review. Pain Pract. 18(8):1083-98, 2018
                                      3. Sujka J et al: Outcomes using cryoablation for postoperative pain control in children following minimally invasive pectus excavatum repair. J Laparoendosc Adv Surg Tech A. 28(11):1383-6, 2018
                                      4. Marshall RH et al: Feasibility of intraoperative nerve monitoring in preventing thermal damage to the "nerve at risk" during image-guided ablation of tumors. Cardiovasc Intervent Radiol. 39(6):875-84, 2016
                                      5. Ahmed M et al: Image-guided tumor ablation: standardization of terminology and reporting criteria--a 10-year update: supplement to the consensus document. J Vasc Interv Radiol. 25(11):1706-8, 2014
                                      6. Kurup AN et al: Neuroanatomic considerations in percutaneous tumor ablation. Radiographics. 33(4):1195-215, 2013
                                      7. Callstrom MR et al: Painful metastases involving bone: percutaneous image-guided cryoablation--prospective trial interim analysis. Radiology. 241(2):572-80, 2006
                                      8. Callstrom MR et al: Painful metastases involving bone: feasibility of percutaneous CT- and US-guided radio-frequency ablation. Radiology. 224(1):87-97, 2002
                                      Related Anatomy
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                                      Related Differential Diagnoses
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                                      References
                                      Tables

                                      Tables

                                      KEY FACTS

                                      • Terminology

                                        • Preprocedure

                                          • Post Procedure

                                            • Outcomes

                                              • Procedure

                                                TERMINOLOGY

                                                • Definitions

                                                  • Ablation: Direct application of chemical or thermal therapies to tumors for tissue destruction
                                                  • Overall survival (OS): Length of time from either date of diagnosis or start of treatment for disease, such as cancer, to date of death of any cause
                                                    • Usually expressed in median ± standard deviation
                                                  • Cancer-specific survival (CSS): Length of time from either date of diagnosis or start of treatment for disease, such as cancer, to date of death from disease
                                                    • Patients who die from causes unrelated to disease are not counted in this measurement
                                                  • Progression-free survival: Length of time (from set point, usually treatment) that patient demonstrates no disease progression
                                                  • Time to progression: Length of time (from set point, usually treatment) until patient shows disease progression
                                                    • Mortalities are excluded
                                                  • Disease-free survival (DFS): Length of time after treatment, until patient dies or shows evidence for recurrent disease
                                                • Ablation Modalities

                                                  • Radiofrequency ablation (RFA)
                                                    • Physics
                                                      • Relies on electrical conduction through tissue for heat generation
                                                      • Closed circuit necessary for conduction; body acts as resistor
                                                      • Direct radiofrequency heating
                                                        • Occurs within millimeters of applicator needle
                                                      • Thermal conduction
                                                        • Heat transfer more distally; therefore, good thermal conductivity crucial for large ablation
                                                        • Quick charring (dehydration) of tissue increases resistance, opens circuit, and limits ablation zone
                                                        • Slow, gradual "cooking" more effective than fast ablation
                                                      • Common current frequency of 400-500 kHz
                                                    • Disadvantages
                                                      • Irregular ablation shape, depends on thermal conductivity of tissue
                                                      • Charring limits effectiveness
                                                      • Heat sink effect
                                                        • Flow of blood in nearby vessels cools tissue, limiting effectiveness
                                                      • Impedance (instead of temperature) regulating systems may lengthen total procedure time and increase ablation zone
                                                      • Grounding pads required for monopolar systems
                                                      • May require slow and lengthy treatment to effectively kill tumor
                                                  • Microwave ablation (MWA)
                                                    • Physics
                                                      • Relies on dielectric heating
                                                        • Alternating electromagnetic (EM) field applied to imperfect dielectric material (tissue); forces water molecules in tissue to oscillate
                                                        • Water molecules oscillate out of phase with EM field
                                                        • Frictional energy loss generates heat
                                                        • Higher water content = better heat absorption and conductivity = larger ablation zone
                                                      • Frequencies often 915 MHz or 2.45 GHz
                                                      • Relative permittivity: How well materials accept EM field (capacitance)
                                                        • Lower the permittivity, the less movement of energy from source dispersed through tissues
                                                        • Low relative permittivity: Bone, spleen
                                                        • High relative permittivity: Muscle, lung, liver
                                                      • Effective conductivity: How well tissue absorbs microwave energy
                                                        • Lower the conductivity, the higher thermal energy deposited locally, and the more effective ablation around antennae
                                                        • Low conductivity: Bone, lung, liver
                                                        • High conductivity: Muscle, blood, spleen
                                                    • Advantages
                                                      • Ablation volume is more predictable, as it does not depend on thermal conductivity of tissue
                                                      • Can pass through and heat tissue at any temperature or water content
                                                      • Less susceptible to heat sink by producing larger areas of active heating
                                                      • Does not require grounding pads
                                                  • Cryoablation
                                                    • Physics
                                                      • Relies on Joules-Thomson effect
                                                        • Compressed gas circulates within double-barreled probe
                                                        • Gas released within probe results in sudden pressure drop
                                                        • Resultant temperature drop cools surrounding tissues
                                                      • Process consists of alternate freezing and thawing of tissue (commonly 10 minutes, 8 minutes, 10 minutes)
                                                      • Multifaceted cellular death mode: Cell membrane fracture, apoptosis, vessel thrombosis/ischemia
                                                      • Argon gas
                                                      • Each probe has characteristic isotherms (size and shape of surface with same temperature)
                                                      • Temperatures drop to ~ -150°C at probe
                                                      • Heat pump effect: Nearby vessels may increase temperature and limit ablation margin
                                                    • Advantages
                                                      • Well tolerated (minimal pain)
                                                      • "Ice ball" readily visible with CT (US/MR) guidance
                                                        • Represents 0°C isotherm (not lethal)
                                                        • Lethal isotherm (-20°C) ~ 5 mm inside visible "ice ball"
                                                      • Operator can sculpt irregularly shaped ablation zone by altering orientation of multiple probes
                                                    • Disadvantages
                                                      • More expensive, as multiple probes may be required
                                                      • System requires gas availability and storage

                                                PREPROCEDURE

                                                • Indications

                                                  • Contraindications

                                                    • Preprocedure Imaging

                                                      • Getting Started

                                                        PROCEDURE

                                                        • Patient Position/Location

                                                          • Baseline Imaging and Planning

                                                            • Probe Insertion/Positioning

                                                              • Added Maneuvers

                                                                • Intraprocedural Monitoring of Patient and Treatment

                                                                  • Completion Imaging

                                                                    • Recovery

                                                                      POST PROCEDURE

                                                                      • Things to Do

                                                                        OUTCOMES

                                                                        • Complications

                                                                          Selected References

                                                                          1. Burke CJ et al: Ultrasound-guided therapeutic injection and cryoablation of the medial plantar proper digital nerve (Joplin's Nerve): sonographic findings, technique, and clinical outcomes. Acad Radiol. ePub, 2019
                                                                          2. Ferrer-Mileo L et al: Efficacy of cryoablation to control cancer pain: a systematic review. Pain Pract. 18(8):1083-98, 2018
                                                                          3. Sujka J et al: Outcomes using cryoablation for postoperative pain control in children following minimally invasive pectus excavatum repair. J Laparoendosc Adv Surg Tech A. 28(11):1383-6, 2018
                                                                          4. Marshall RH et al: Feasibility of intraoperative nerve monitoring in preventing thermal damage to the "nerve at risk" during image-guided ablation of tumors. Cardiovasc Intervent Radiol. 39(6):875-84, 2016
                                                                          5. Ahmed M et al: Image-guided tumor ablation: standardization of terminology and reporting criteria--a 10-year update: supplement to the consensus document. J Vasc Interv Radiol. 25(11):1706-8, 2014
                                                                          6. Kurup AN et al: Neuroanatomic considerations in percutaneous tumor ablation. Radiographics. 33(4):1195-215, 2013
                                                                          7. Callstrom MR et al: Painful metastases involving bone: percutaneous image-guided cryoablation--prospective trial interim analysis. Radiology. 241(2):572-80, 2006
                                                                          8. Callstrom MR et al: Painful metastases involving bone: feasibility of percutaneous CT- and US-guided radio-frequency ablation. Radiology. 224(1):87-97, 2002