Osteoid Osteomas

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The Use of Microwaves Ablation in the Treatment of Epiphyseal
Osteoid Osteomas

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Osteoid Osteomas

  1. 1. CLINICAL INVESTIGATION The Use of Microwaves Ablation in the Treatment of Epiphyseal Osteoid Osteomas Antonio Basile • Giovanni Failla • Angelo Reforgiato • Giovanni Scavone • Elena Mundo • Martina Messina • Giuseppe Caltabiano • Francesco Arena • Viola Ricceri • Antonio Scavone • Salvatore Masala Received: 2 July 2013 / Accepted: 22 July 2013 Ó Springer Science+Business Media New York and the Cardiovascular and Interventional Radiological Society of Europe (CIRSE) 2013 Abstract Objective This study was designed to demonstrate the feasibility and the reliability of microwave ablation (MWA) of epiphyseal osteoid osteomas (OO). Materials and Methods From February to November 2012, 7 patients (4 males and 3 females; age range 16–30 years) with epiphyseal OOs were treated with MWA. The treatment was performed with 16 G antennas with a power of 20 W for 2 min. The OOs were approa- ched by using coaxial needles inserted with hammer or with automatic drill. All patients underwent spinal anaes- thesia, with posttreatment 6–8 h observation before dis- charging. We treated epiphyseal OOs placed away from nervous and vascular nontarget structures, located in: femoral head (n = 2), femoral lesser trochanter (n = 2), femoral neck (n = 2), and proximal tibial epiphysis (n = 1). CT was used to visualize the nidus and to insert the needle for thermal ablation and for postprocedure control. Technical success was considered the positioning of the antenna in the nidus, while the efficacy of treatment was clinically evaluated as the complete remission of pain after the procedure by using the visual analogue score (VAS). Follow-up was performed by using VAS score 1 day, 1 week, and 1, 3, and 6 months after the procedure, whereas MRI examination was performed immediately after the procedure, at 1 month, and in any case of recur- rence. Complications were also recorded. Results All patients experienced resolution of the symp- tomatology (VAS = 0) in *1 week until the last follow- up, with residual VAS 2 points occurring only from 1 to 7 days after the procedure. No intraprocedural complication was noted, whereas one patient had back pain for 2 months after the procedure, likely due to spinal analgesic injection. Conclusions In our experience, MWA can be safely performed with excellent results without complications in selected cases of epiphyseal OOs; however, the clinical significance of this report is limited because there were only few patients included in this study. Thus, these data must be confirmed by further and larger studies. Keywords Osteoid osteoma Á Radiofrequency ablation Á Microwaves ablation Radiofrequency ablation (RFA) is considered the less invasive technique for the treatment of osteoid osteomas (OOs), a small benign bone neoplasm, often with a diam- eter of 1 cm [1, 2]. For decades, surgery represented the standard therapy for such lesions. The use of RFA was described for the first time in 1989, and the first results were published in 1992 [3]. Today, this minimally invasive procedure is widely available, safe, and effective for neo- plasms located in the liver, kidney, lung, and also for both A. Basile Á G. Failla Á A. Reforgiato Á G. Scavone Á E. Mundo Á M. Messina Á G. Caltabiano Á F. Arena Á V. Ricceri Á A. Scavone Department of Diagnostic and Interventional Radiology, Garibaldi Centro Hospital, Piazza Santa Maria del Gesu`, 95124 Catania, Italy A. Basile (&) Via Trieste 14, 95127 Catania, Italy e-mail: antodoc@yahoo.com G. Failla Department of Radiology, Policlinico Vittorio Emanuele, Via Santa Sofia 22, 95100 Catania, Italy S. Masala Department of Diagnostic Imaging and Interventional Radiology, Molecular Imaging and Radiotheraphy, Policlinico Universitario Tor Vergata, 00133 Rome, Italy 123 Cardiovasc Intervent Radiol DOI 10.1007/s00270-013-0722-z
  2. 2. primary and secondary bone tumours [4–6]. Also, laser ablation has been used for OOs in particularly risky loca- tions, such as spinal [7]. The clinical success of RFA of OOs rates are in the range of 55–100 % for initial success [8, 9] and 88.8–100 % if reablation is considered [8]. Its clinical success has been reported to range from 67 to 96 % with a recurrence rate from 5 to 10 % [2, 3, 10, 11]. With the same technique and the same coaxial intro- duction systems, it is possible to insert microwaves antennas in place of radiofrequency needles. Microwave ablation (MWA) induces cellular death trough coagulation necrosis caused by high intratumoral temperature, this is produced by the agitation of water molecules exposed to the electromagnetic field; these characteristic can overtake major limitations of RFA related to incomplete nidus ablation [4]. The purpose of our case series was to dem- onstrate the feasibility and the reliability of treatment with MWA of epiphyseal OOs. Materials and Methods From February 2012 to November 2012, 7 patients (4 males and 3 females; age range 16–39 years; age range from 16 to 30 years, respectively) underwent CT-guided MWA of epiphyseal OOs. All patients had been referred for treatment if they had both clinical and radiological features of OO and if lesions were located in the long bone epiphysis, thus away from nervous and vascular nontarget structures. All patients had never been treated. The lesions were located in: femoral head (n = 2), lesser femoral tro- chanter (n = 2), femoral neck (n = 2), and proximal tibial epiphysis (n = 1) (Figs. 1, 2A–D). The lesion diameter ranged from 4 to 11 mm (Table 1). All patients had increasing pain during the night with a mean pretreatment visual analogue score (VAS = 2) during the day (range 0–5) and VAS = 6 (range 4–7) during the night. Six patients needed pain medication during the night, whereas only one also during the day. Patients were informed of alternative treatments, including the option of medical management. Informed consent was obtained in all cases. All patients underwent spinal anaesthesia and deep sedation for pain relief under the anaesthesiologist guidance. CT (Optima, GE Health- care, USA) was used to visualize the nidus and to insert the needle for thermal ablation and for postprocedure control. Interventional radiologists examined CT images and mul- tiplanar reconstruction to identify the nidus and to plan needles trajectory. The guiding CT protocol refers to 4/8 continuous slices of 1-mm thickness with low kV (100) and mA (50) to reduce the radiation exposure, parallel to the needle trajectory. For the OOs located in the lesser tro- chanter, the lesions were approached by drilling from the lateral portion of the bone to give more support to the needle and not get out from the cortex. Fig. 1 Patient 1: magnetic resonance imaging (A), showing a femoral OO (arrow) not well seen at coronal and axial CT scans (B, C arrows), treated with MW antenna (D) A. Basile et al.: The use of MWA in the treatment of epiphyseal OO 123
  3. 3. The OOs were approached by using coaxial needles (Bonopty, Radix, Sweden) inserted manually or with hammer or automatic drill (Oncontrol Power Driver, Vidacare, Shavano Park, TX, USA). An antenna of 16 G (HS, Aprilia, Italy) was introduced to ensure that the antenna active tip of 2 cm was kept inside the bone Fig. 2 Patient 2: lesser trocanteric OO with thick osteosclerotic rim: A coronal and B axial CT scans, treated with MWA, 16-gauge (Amica, HS, Italy) 20 W 9 2 min; D posttreatment CT scan; E MRI performed after the procedure, STIR axial sequence, coronal T1 turbo spin echo. F, G Axial T1 turbo spin echo weighted shows post- ablation signal intensity of the bone tissue. ROI region of interest was positioned to measure the surface area of the ablation zone (D, E) and three dimensions were obtained (F, G) A. Basile et al.: The use of MWA in the treatment of epiphyseal OO 123
  4. 4. trajectory. The applicator we used has to be inserted in the bone for at least 2 cm, which correspond to the antenna length, to avoid heating tissues outside the bone. The treatment was performed by connecting the antenna to the generator (HS, Aprilia, Italy) with a power of 20 W for 2 min as suggested by manufacturer. After removal of the needle system, CT scan was performed to evaluate ablation area and identify possible complications. All patients underwent spinal anaesthesia, with posttreatment 6–8 h observation before discharge. Technical success was considered the positioning of the antenna in the nidus, while the efficacy of treatment was clinically evaluated as the complete remission of pain after the procedure by using the (VAS 1 without medication) obtained by outpatient visit or telephone interview. Follow- up was performed by using VAS score at 1 day, 1 week, and 1, 3, and 6 months after the procedure while MRI examination was performed immediately after the proce- dure, after 1 month, and in any case of recurrence. MRI was performed with a 1.5-T imager (Philips, Ingenia 1.5T). The imaging protocols included: multiplanar T1-weighted, T2-weighted, and STIR sequences. No contrast medium was administered, even if contrast enhancement is known to be a predictor of recurrence. The imaging parameters used were: repetition time 480–670 ms, echo time 20 ms for T1-weighted sequences; repetition time 2,400–4,120 ms, echo time 90 ms for T2- weighted sequences; repetition time 4,104 ms, inversion time 140 ms, echo time 30 ms for STIR sequences; a 18–22 cm FOV, 4–5 mm section thickness with a 0.4- to 0.5-mm interslice gap, 284–512 9 246–512 matrix and 1-2 NEX. Complications also were recorded. Results All patients experienced resolution of the symptomatology (VAS 1 without medication) until the last follow-up, with residual VAS 2 points occurring only from 1 to 7 days after the procedure. Follow-up time ranged from 5 to 13 months (Table 1). No intraprocedural complication was noted, whereas one patient (no. 2) had back pain for 2 months after the procedure, likely due to spinal analgesic injection. MR images showed the nidus as hypointense area in T1- weighted sequences and hyperintense area in long TR sequences in all of the cases (n = 7); the surrounding bone marrow was inhomogeneously hyperintense in long TR sequences in all cases (n = 7) and in three cases the same signal was detected along the needle pathway; hyperintense signal of the adjacent soft tissue was detected in three cases in long TR sequences (Fig. 2E–H); intra-articular effusionof the hip was revealed in both lesions located in the femoral neck. We measured approximately the ablation area at 1-month MR follow-up, and we had a mean of 21 9 12 9 14-mm3 ablation area (Table 1). Discussion The reduction and elimination of pain caused by OO is the goal of the treatment. The recurrence rate for RFA has been reported to be from 5 to 10 % [1, 3, 11]. In a recent article [12], the authors stated that treatment failure can occur more frequently in lesions treated with only one needle position, especially but not exclusively when needle placement was inaccurate, missing the nidus ablation, or when lesions were large. The use of only one needle position is the most important independent parameter that is associated with an increased risk for treatment failure in lesions of all sizes. The main problem related to the one needle insertion is the relative inadequate ablation area; multiple needle insertions lead to a time-spending proce- dure with an increasing radiation exposure especially for young patients, because the operator has to insert the needle and give energy, thus replaces the needle and gives Table 1 Summary of patient population Patient Age (years)/ gender Pretreatment VAS (d = day) (n = night) Lesion location Maximum diameter (mm) Follow-up (months) Last follow-up VAS Ablation area measured at 1 month MR (mm3 ) 1 22/m d = 1 n = 6 (needing medication) Femoral neck 4 13 0 21 9 13 9 13 2 30/m d = 2 n = 6 (needing medication) Lesser trocanter 11 10 0 22 9 11 9 13 3 16/f d = 0, n = 7 (needing medication) Femoral head 6 9 0 24 9 12 9 15 4 29/f d = 4, n = 7 (needing medication) Femoral neck 8 8 1 20 9 13 9 14 5 18/m d = 1 n = 6 (needing medication) Proximal tibial epiphysis 4 8 0 21 9 13 9 15 6 16/f d = 5 (needing medication) n = 7 (needing medication) Lesser trocanter 10 7 1 19 9 11 9 13 7 18/m d = 1 n = 4 Femoral head 8 5 0 22 9 14 9 16 A. Basile et al.: The use of MWA in the treatment of epiphyseal OO 123
  5. 5. again energy. The insufficient ablation area also can be related to the impossibility to achieve the needed temper- ature for sufficient time due to problems in current mod- ulation or to high impedance inside the OO [13]. Many studies have assessed the use of MW for the ablation of lesions located in liver, lungs, kidneys, or adrenal gland and in treatment of cystic masses, such as adrenal metastasis, and in these cases are valid options for RF ablation [14]. MWA induces cellular death trough coagulation necro- sis caused by high intratumoral temperature produced by the agitation of water molecules exposed to the electro- magnetic field. For the supramentioned reasons, micro- waves are insensitive to impedance thus provide deeper penetration and more successful heating resulting in larger ablation areas [4, 14]. The characteristic of MWA could overtake the limitation of RFA for OOs, due to the need for multiple needle inser- tions and to inadequate ablation area also potentially related to high impedance and low thermal conduction present in these lesions. MWA is in fact able to produce faster heating, higher intralesional temperature, and bigger ablation area even with only one needle insertion, potentially even if not precisely located in the centre of the nidus [4]. Until now, there is no experience in the literature with treatment of OOs with microwaves likely because of the risk of nontarget damage in small lesions. Benign bone lesions and especially OOs often are *1 cm and require short ablation zones that many systems are not capable to generate. Today, with modulating energy and time we are able to produce smaller ablation areas, thus it is feasible to use them to treat OOs away from nontarget neurological structures. Some authors [14] have established that the use of MW is more advantageous in tissue with high impedance, such as bone, because higher impedance reduces energy depo- sition from current RF generators, which, in turn, leads to a smaller temperature increase and potentially increased treatment failure rates. In our preliminary experience to evaluate the feasibility of MWA for epiphyseal OOs, we chose lesions located away from neurological structures. Furthermore, we had to choose a needle trajectory of at least 2 cm inside bone, as suggested by manufacturer, warranting that the 2-cm tip of the antennas was ‘‘insulated by bone tissue.’’ This technical precaution limits the use of MWA, because many OOs do not allow for 2-cm bone coverage, for example, those periosteal or subperiosteal. For these reasons, we enrolled for this study only epiphyseal OOs. Potentially, with MWA we do not need to put the antenna in the long axis of the lesion and we do not need multiple insertions, because we can achieve an effective ablation of the entire lesion exploiting its ability to create a larger area of necrosis. Furthermore, theoretically MW antennas do not need to be perfectly in the centre of the nidus, such as for RFA, and this could be helpful in cases of not perfectly viewable lesions or for lesions with a thick osteosclerosis difficult to over cross. In our series, we also had an approximate ablation area very similar in every case (Table 1). Our study has some major limitations, in particular the small group of patients. Whilst this would need to be confirmed by larger and prospective, randomized trials, our data suggest that MWA of OOs can be considered a feasible alternative to RFA in selected cases, potentially overtaking the limitations of the latter method, in particular that related to the incomplete nidus ablation secondary to the high intralesional imped- ance or to the necessity of multiple needle insertion. In our experience, MWA can be performed with excellent results without complications in selected cases, in particular those located in the epiphyses of long bones, because in that location we are likely away from vascular or neurological nontarget structures. Furthermore, we have several possible bone accesses trajectories, ensuring that the 2-cm active tip of the antenna is kept inside the bone. Conflict of interest None References 1. Rosenthal DI, Hornicek FJ, Torriani M et al (2003) Osteoid osteoma: percutaneous treatment with radiofrequency energy. Radiology 229(1):171–175 2. Kjar RA, Powell GJ, Schilcht SM et al (2006) Percutaneous radiofrequency ablation for osteoid osteoma: experience with a new treatment. Med J Aust 184:563–565 3. Gangi A, Tsoumakidou G, Buy X et al (2010) Quality improvement guidelines for bone tumour management. Cardio- vasc Intervent Radiol 33:706–713 4. Lubner MG, Brace CL, Hinshaw JL et al (2010) Microwave tumor ablation: mechanism of action, clinical results, and devi- ces. J Vasc Interv Radiol 21(8 Suppl):S192–S203 5. Motamedi D, Learch TJ, Ishimitsu DN et al (2009) Thermal ablation of osteoid osteoma: overview and step-by-step guide. Radiographics 29(7):2127–2141 6. Gangi A, Basile A, Buy X et al (2005) Radiofrequency and laser ablation of spinal lesions. Semin Ultrasound CT MR 26(2):89–97 7. Gangi A, Alizadeh H, Wong L et al (2007) Osteoid osteoma: percutaneous laser ablation and follow-up in 114 patients. Radi- ology 242:293–301 8. Mahnken AH, Bruners P, Delbru¨ck H et al (2011) Radiofre- quency ablation of osteoid osteoma: initial experience with a new monopolar ablation device. Cardiovasc Intervent Radiol 34: 579–584 9. Mastrantuono D, Martorano D, Verna V et al (2005) Osteoid osteoma: our experience using radio-frequency (RF) treatment. Radiol Med (Torino) 109:220–228 10. Rehnitza C, Sprengela SD, Lehnerb B et al (2012) CT-guided radiofrequency ablation of osteoid osteoma and osteoblastoma: clinical success and long-term follow-up in 77 patients. Eur J Radiol 81(11):3426–3434 A. Basile et al.: The use of MWA in the treatment of epiphyseal OO 123
  6. 6. 11. Rosenthal DI, Springfield DS, Gebhardt MC et al (1995) Osteoid osteoma: percutaneous radio-frequency ablation. Radiology 197:451–454 12. Vanderschueren GM, Taminiau AHM, Obermann WR et al (2004) Osteoid osteoma: factors for increased risk of unsuc- cessful thermal coagulation. Radiology 233:757–762 13. Pinto CI, Taminiau AHM, Vanderschueren GM et al (2002) Technical considerations in CT-guided radiofrequency thermal ablation of osteoid osteoma: tricks of the trade. AJR Am J Roentgenol 179:1633–1642 14. Brace CL, Hinshaw JL, Laeseke PF et al (2009) Pulmonary thermal ablation: comparison of radiofrequency and microwave devices by using gross pathologic and CT findings in a swine model. Radiology 251(3):705–711 A. Basile et al.: The use of MWA in the treatment of epiphyseal OO 123

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