Smartphone application with 3D-printed needle guide for faster and more accurate CT-guided interventions in a phantom.

OBJECTIVE: This study is to determine whether a needle guidance device combining a 3D-printed component with a smartphone would decrease the number of passes and time required to perform a standard CT-guided needle procedure in a phantom study. MATERIALS AND METHODS: A 3D-printed mechanical guide with built-in apertures for various needle sizes was designed and printed. It was mounted on a smartphone and used to direct commercially available spring-loaded biopsy devices. A smartphone software application was developed to use the phone's sensors to provide the real-time location of a lesion in space, based on parameters derived from preprocedural CT images. The physical linkage of the guide, smartphone, and needle allowed the operator to manipulate the assembly as a single unit, with real-time graphical representation of the lesion shown on the smartphone display. Two radiology trainees and 3 staff radiologists targeted 5 lesions with and without the device (50 total procedures). The number of passes and time taken to reach each lesion were determined. RESULTS: Use of the smartphone needle guide decreased the mean number of passes (with guide, 1.8; without guide, 3.4; P < 0.001) and mean time taken (with guide, 1.6 min; without guide, 2.7 min; P = 0.005) to perform a standard CT-guided procedure. On average, the decreases in number of passes and procedure time were more pronounced among trainees (P < 0.001). CONCLUSION: The combination of a mechanical guide and smartphone can reduce the number of needle passes and the amount of time needed to reach a lesion in a phantom for both trainees and experienced radiologists.

Keratin-Positive Giant Cell-Rich Tumor of Bone Harboring an HMGA2::NCOR2 Fusion: Two Cases, Including a Patient With Metastatic Disease, and Review of the Literature.

Giant cell-rich lesions of bone represent a heterogeneous group of entities which classically include giant cell tumor of bone, aneurysmal bone cyst, nonossifying fibroma, and Brown tumor of hyperparathyroidism. A recently described subset of giant cell-rich tumors involving bone and soft tissue has been characterized by recurrent HMGA2::NCOR2 fusions and keratin expression. The overlapping clinical, radiographic, and morphological features of these giant cell-rich lesions provide a unique diagnostic challenge, particularly on biopsy. We present 2 additional cases of keratin-positive giant cell-rich tumor of bone with HMGA2::NCOR2 fusions, including 1 patient who developed metastatic disease.

Osteoid osteomas of the hands and feet: a series of 71 cases.

Osteoid osteomas typically arise in the long bones of extremities. Patients often report pain relieved by NSAIDS, and radiographic findings are often sufficient for diagnosis. However, when involving the hands/feet, these lesions may go unrecognized or misdiagnosed radiographically due to their small size and prominent reactive changes. The clinicopathologic features of this entity involving the hands and feet are not well-described. Our institutional and consultation archives were searched for all cases of pathologically confirmed osteoid osteomas arising in the hands and feet. Clinical data was obtained and recorded. Seventy-one cases (45 males and 26 females, 7 to 64 years; median 23 years) arose in the hands and feet, representing 12% of institutional and 23% of consultation cases. The clinical impression often included neoplastic and inflammatory etiologies. Radiology studies demonstrated a small lytic lesion in all cases (33/33), the majority of which had a tiny focus of central calcification (26/33). Nearly, all cases demonstrated cortical thickening and/or sclerosis and perilesional edema which almost always had an extent two times greater than the size of the nidus. Histologic examination showed circumscribed osteoblastic lesions with formation of variably mineralized woven bone with single layer of osteoblastic rimming. The most common growth pattern of bone was trabecular (n = 34, 48%) followed by combined trabecular and sheet-like (n = 26, 37%) with only 11 (15%) cases presenting with pure sheet-like growth pattern. The majority (n = 57, 80%) showed intra-trabecular vascular stroma. No case showed significant cytology atypia. Follow up was available for 48 cases (1-432 months), and 4 cases recurred. Osteoid osteomas involving the hands and feet follow a similar age and sex distribution as their non-acral counterparts. These lesions often present with a broad differential diagnosis and may initially be confused with chronic osteomyelitis or a reactive process. While the majority of cases have classic morphologic features on histologic exam, a small subset consists solely of sheet-like sclerotic bone. Awareness that this entity may present in the hands and feet will help pathologists, radiologists, and clinicians accurately diagnose these tumors.

Deep Learning Diagnosis and Classification of Rotator Cuff Tears on Shoulder MRI.

BACKGROUND: Detection of rotator cuff tears, a common cause of shoulder disability, can be time-consuming and subject to reader variability. Deep learning (DL) has the potential to increase radiologist accuracy and consistency. PURPOSE: The aim of this study was to develop a prototype DL model for detection and classification of rotator cuff tears on shoulder magnetic resonance imaging into no tear, partial-thickness tear, or full-thickness tear. MATERIALS AND METHODS: This Health Insurance Portability and Accountability Act-compliant, institutional review board-approved study included a total of 11,925 noncontrast shoulder magnetic resonance imaging scans from 2 institutions, with 11,405 for development and 520 dedicated for final testing. A DL ensemble algorithm was developed that used 4 series as input from each examination: fluid-sensitive sequences in 3 planes and a sagittal oblique T1-weighted sequence. Radiology reports served as ground truth for training with categories of no tear, partial tear, or full-thickness tear. A multireader study was conducted for the test set ground truth, which was determined by the majority vote of 3 readers per case. The ensemble comprised 4 parallel 3D ResNet50 convolutional neural network architectures trained via transfer learning and then adapted to the targeted domain. The final tear-type prediction was determined as the class with the highest probability, after averaging the class probabilities of the 4 individual models. RESULTS: The AUC overall for supraspinatus, infraspinatus, and subscapularis tendon tears was 0.93, 0.89, and 0.90, respectively. The model performed best for full-thickness supraspinatus, infraspinatus, and subscapularis tears with AUCs of 0.98, 0.99, and 0.95, respectively. Multisequence input demonstrated higher AUCs than single-sequence input for infraspinatus and subscapularis tendon tears, whereas coronal oblique fluid-sensitive and multisequence input showed similar AUCs for supraspinatus tendon tears. Model accuracy for tear types and overall accuracy were similar to that of the clinical readers. CONCLUSIONS: Deep learning diagnosis of rotator cuff tears is feasible with excellent diagnostic performance, particularly for full-thickness tears, with model accuracy similar to subspecialty-trained musculoskeletal radiologists.

Extra-abdominal desmoid fibromatosis: Cryoablation versus traditional therapies.

PURPOSE: To retrospectively review the various methods used to treat extra-abdominal desmoid fibromatosis (EDF) at our institution to compare treatment response and complications with those for the emerging option of percutaneous cryoablation therapy. METHODS: A single-center retrospective review was conducted to identify patients with EDF who underwent some form of treatment for EDF in any combination (including medical therapy, surgery, percutaneous ablation and radiation therapy) at our institution between January 2007 and January 2020. Patients with pathological evidence of EDF and pretreatment and posttreatment images were included. Medical records and imaging data were also reviewed. Treatment response assessment was based on tumor size on follow-up imaging. RESULTS: A total of 41 patients (30 women; mean age, 34 y; range, 18-79 y) were included in the study. The extremities (44%) and back (22%) were the most common locations of EDF. Patients underwent a variety of treatment methods, including medical therapy (31 patients), surgery (24 patients), cryoablation (7 patients), radiation therapy (6 patients), and radiofrequency ablation (4 patients). Reduction in lesion size after at least 3 months of follow-up was most common in patients who underwent surgery alone (5 patients) or cryoablation (4 patients). Among all study patients, there were 10 minor complications and 3 major complications. Complication rates were lowest in patients who underwent cryoablation (no complications). CONCLUSION: Although further work is needed, the early data in this study offers promising results regarding the clinical application of cryoablation for EDF, which appears safer than radiofrequency ablation and a potentially effective.

Preoperative cryoablation of a hypervascular bone metastasis: A case of effective devascularization before preoperative embolization.

Image-guided cryoablation has become a common approach for the palliative treatment of painful metastatic bone lesions, and indications for this procedure have expanded to include local control of bone metastases. We report a case in which cryoablation was performed on a large hypervascular renal cell carcinoma bone metastasis before surgical fixation of an impending fracture. In this case, cryoablation reduced the patient's pain but also appeared to result in devascularization of the tumor, thus obviating the need for preoperative embolization. This case raises the possibility that image-guided cryoablation may represent an alternative to preoperative embolization for vascular tumors while also serving a palliative function.

Updates and Ongoing Challenges in Imaging of Multiple Myeloma: AJR Expert Panel Narrative Review.

Advances in the understanding and treatment of multiple myeloma have led to the need for more sensitive and accurate imaging of intramedullary and extramedullary disease. This role of imaging is underscored by recently revised imaging recommendations of the International Myeloma Working Group (IMWG). This narrative review discusses these recommendations from the IMWG for different disease stages, focusing on advanced whole-body modalities, and addresses related challenges and controversies. In the recommendations, whole-body low-dose CT is central in initial patient assessment, replacing the conventional skeletal survey. Although the recommendations favor MRI for diagnosis because of its superior sensitivity and utility in identifying myeloma-defining events, FDG PET/CT is recommended as the modality of choice for assessing treatment response. Consensus opinions are offered regarding the role of imaging in multiple myeloma for characterization of disease distribution, determination of prognosis, and response evaluation.

Magnetic resonance imaging of deltoid muscle/tendon tears: a descriptive study.

OBJECTIVE: To describe the MRI features of deltoid tears and to evaluate tear characteristics in patient groups based on history of trauma and rotator cuff tear (RCT). MATERIALS AND METHODS: The records of patients who underwent shoulder MRI at our institution between July 2007 and June 2018 were retrospectively reviewed to identify deltoid tears, and patients were divided into groups based on history of recent trauma and presence of RCT. Images were reviewed to identify the location and size of the deltoid tear; the presence or absence of RCT, muscle atrophy, tendon retraction, humeral head subluxation, soft tissue edema, and additional pathologies were also noted. Medical records were reviewed for information about history of steroid injection, previous rotator cuff surgery, and treatments used. RESULTS: Among 69 patients with deltoid tears (45 men; mean age, 65.2 years; range, 19-89 years), patients with RCTs and no trauma had the highest frequency of deltoid tears in the middle portion (p = 0.005). Only patients with RCTs had undergone steroid injection or rotator cuff surgery. Two patients had deltoid tear without RCT and without recent trauma; these patients demonstrated evidence of calcific tendinopathy and chronic subacromial-subdeltoid bursitis. CONCLUSION: The middle (acromial) portion of the deltoid is more frequently affected in patients with RCTs than in those with trauma. Although deltoid tears are commonly associated with RCT, calcific tendinopathy and chronic bursitis may also be seen in patients with deltoid tears.

Does PET/CT Aid in Detecting Primary Carcinoma in Patients with Skeletal Metastases of Unknown Primary?

BACKGROUND: Patients older than 40 years presenting with osteolytic bone lesions are likely to have a diagnosis of carcinoma, even if they had no prior cancer diagnosis. For patients with no prior cancer diagnosis, there is a well-accepted algorithm to determine a potential primary site. That algorithm, however, leaves approximately 15% of people without a detectable primary tumor site, making treatment decisions extremely difficult. Positron emission tomography (PET) fused with CT, more commonly known as PET/CT, has emerged as an important staging modality for many other malignancies but has been used in a very limited fashion in musculoskeletal oncology. QUESTIONS/PURPOSES: We asked (1) What is the ability of PET/CT to detect the source of the primary tumor in patients with a skeletal metastasis of unknown primary? (2) How does PET/CT perform in detecting metastases in other sites in patients with a skeletal metastasis of unknown primary? METHODS: A retrospective analysis between 2006 and 2016 of the pathology database of a single tertiary center identified 35 patients with a biopsy-proven skeletal metastasis (histologically confirmed carcinoma or adenocarcinoma) and a PET/CT scan that was performed after the standard diagnostic evaluation of the primary cancer site. Patients were identified through use of our pathology database to identify all biopsy-proven bone carcinomas. This was then cross referenced with our imaging database to identify all patients who were at any time evaluated with PET/CT. During this time, we identified 1075 patients with biopsy-proven metastatic bone disease through our pathology database. Any indication for a PET/CT was included, and was most often done for staging of the identified malignancy or evaluation for the unknown source. Data regarding the ability of PET/CT to find or confirm the primary cancer and all metastatic sites were evaluated. The standard diagnostic evaluation (history and physical, laboratory evaluation, CT of the chest/abdomen/pelvis and whole body bone scan) identified the primary cancer in 22 of the 35 patients. Among the 35 patients, there were a total of 176 metastatic sites of disease identified, with 115 identified with the standard diagnostic evaluation (before PET/CT). RESULTS: Among patients with a skeletal metastasis of unknown primary, PET/CT was unable to identify the primary cancer in 12 of 13 patients. PET/CT confirmed the site of the known primary cancer in all 22 patients. There were 176 total metastatic sites. Of the 115 metastases known before PET/CT, PET/CT failed to identify three of 115 (3% false-negative rate). CONCLUSIONS: PET/CT may not provide any additional benefit over the standard evaluation for identification of the primary cancer in patients with a skeletal metastasis of unknown primary, although it may have efficacy as a screening tool equivalent or superior to the standard diagnostic algorithm for evaluation of the overall metastatic burden in these patients. LEVEL OF EVIDENCE: Level III, diagnostic study.

Isolated septic facet joints: an underdiagnosed distinct clinical entity.

OBJECTIVES: We review a series of isolated septic facet joints (ISFJ) that present as a distinct clinical entity compared with spondylodiscitis. We aim to raise awareness that septic facet joints are not a rare entity in the era of modern imaging. METHODS: We reviewed 353 patients with confirmed spine infections from 2008 to 2017. Of the 353 cases, there were 152 septic facet joints based on MR imaging. Sixty-two presented as ISFJ without evidence of spondylodiscitis and were reviewed. RESULTS: Patients were predominantly male 38/62 (61%). The mean age was 56.7 years. Onset of back pain was more acute compared with spondylodiscitis and usually unilateral. The distribution was as follows: 6 cervical, 12 thoracic, and 44 lumbar facets. The majority of ISFJ, 53/62 (85%), were associated with an epidural abscess (EDA) 53/62. The cervical and thoracic EDA required surgical decompression more frequently than lumbar; 100%, 75%, and 53% respectively. Pathogen was identified in 59/62 (95%) cases. Most cases were associated with bacteremia 50/62 (81%). Seven ISFJ were introduced iatrogenically. All iatrogenic ISFJ required surgical decompression. CONCLUSION: Septic facet joints are not rare, but frequently overlooked as the origin of an epidural abscess. The majority of cases are hematogenously seeded and associated with bacteremia. Surgical decompression is frequently required secondary to the high incidence of associated epidural abscess. Iatrogenic septic facet joints are rare but associated with significant morbidity. From a clinical standpoint, it is helpful to delineate the origin of EDA as either secondary to spondylodiscitis or SFJ.

Osteoid Osteoma Masquerading as Cholelithiasis: A Case Report.

CASE: We present a case report of an 18-year-old woman who presented to a general surgeon with a several month history of intermittent right upper quadrant pain, strongly suggestive of symptomatic cholelithiasis and underwent a laparoscopic cholecystectomy. She was eventually found to have an osteoid osteoma (OO) of the right eighth rib. She was treated with radiofrequency ablation with complete resolution of symptoms 1 month after treatment. CONCLUSIONS: In cases where a patient's age and risk factors would make the diagnosis of cholelithiasis less likely, OO should be added to the differential diagnosis of symptomatic right upper quadrant pain.

Case 272: Decubital Ischemic Fasciitis.

HistoryA 92-year-old bedridden woman presented to the emergency department from an assisted living facility with fever, cough, and swelling over the right lateral hip. She had baseline dementia and frailty and had been bedridden for 4 years. She did not have any recent falls or history of trauma at the site of swelling. She had a history of diffuse large B-cell lymphoma that had been diagnosed and treated 7 years ago, and thoracoabdominal CT at last follow-up 3 years ago did not show any recurrence. Physical examination findings were unremarkable except for a painful hard and fixed mass measuring approximately 5 × 5 × 10 cm (in the transverse, anteroposterior, and craniocaudal directions, respectively) located at the right lateral superior thigh. The overlying skin was intact, without any color changes. Pertinent blood test results showed an increased white blood cell count of 13,000/µL (13 × 109/L) (normal range, 3700-11,000/µL [3.7-11 × 109/L]). The remaining hematologic and biochemical test results were normal. Abdominal and pelvic CT performed at presentation did not show any abnormal lymph nodes. Because chest radiography showed consolidation in addition to typical clinical picture, the patient was diagnosed with pneumonia and underwent antibiotic treatment for 3 weeks. US and Doppler US of the mass were performed. MRI was not performed because the patient had a pacemaker; instead, CT of the lower extremity was performed.

Case 272.

History A 92-year-old bedridden woman presented to the emergency department from an assisted living facility with fever, cough, and swelling over the right lateral hip. She had baseline dementia and frailty and had been bedridden for 4 years. She did not have any recent falls or history of trauma at the site of swelling. She had a history of diffuse large B-cell lymphoma that had been diagnosed and treated 7 years ago, and thoracoabdominal CT at last follow-up 3 years ago did not show any recurrence. Physical examination findings were unremarkable except for a painful hard and fixed mass measuring approximately 5 × 5 × 10 cm (in the transverse, anteroposterior, and craniocaudal directions, respectively) located at the right lateral superior thigh. The overlying skin was intact, without any color changes. Pertinent blood test results showed an increased white blood cell count of 13 000/µL (13 ×109/L) (normal range, 3700-11 000/µL [3.7-11 ×109/L]). The remaining hematologic and biochemical test results were normal. Abdominal and pelvic CT performed at presentation did not show any abnormal lymph nodes. Because chest radiography showed consolidation in addition to typical clinical picture, the patient was diagnosed with pneumonia and underwent antibiotic treatment for 3 weeks. US ( Fig 1 ) and Doppler US ( Fig 2 ) of the mass were performed. MRI was not performed because the patient had a pacemaker; instead, CT of the lower extremity was performed ( Fig 3a , 3b ). Figure 1: US image of the mass at the level of the greater trochanter. Figure 2: Doppler US image of the caudal portion of the mass. Figure 3a: (a) Axial unenhanced CT image of the lesion at the level of the greater trochanter. (b) Coronal unenhanced CT image of the mass at the level of the greater trochanter. Figure 3b: (a) Axial unenhanced CT image of the lesion at the level of the greater trochanter. (b) Coronal unenhanced CT image of the mass at the level of the greater trochanter.

Bony changes of the tibia secondary to pes anserine bursitis mimicking neoplasm.

OBJECTIVE: To describe the radiological features of pes anserine bursitis with intramedullary extension and cortical scalloping and to determine the prevalence of these bony changes among patients with pes anserine bursitis. MATERIALS AND METHODS: Reports of knee magnetic resonance imaging (MRI) examinations performed at our institution between July 2007 and June 2017 in patients with pes anserine bursitis were retrospectively reviewed, and a total of 542 cases showing MR evidence of pes anserine bursitis were identified. From these, cases of pes anserine bursitis with intramedullary extension and cortical scalloping were identified. Two experienced musculoskeletal radiologists evaluated the MRI by consensus. The medical records of these patients were also reviewed. RESULTS: Eight patients were diagnosed with pes anserine bursitis with bony changes (prevalence, 1.47% [8 out of 542]), over the study period. All of these patients had a history of chronic knee pain. Seven patients also underwent radiography at the time of diagnosis; these images demonstrated variable appearances depending on the depth of the cortical scalloping and intramedullary extension. On MRI, all patients demonstrated a mass-like fluid extension around the pes anserine bursa and into the bone. None of the patients underwent biopsy; diagnosis was based on MRI features alone. CONCLUSION: Pes anserine bursitis with intramedullary extension is an unusual presentation of bursitis that may simulate a neoplasm clinically and radiologically. To avoid misdiagnosis, radiologists should be aware of the occurrence of osseous changes in the tibia confluent with pes anserine bursitis.

Quantification of fat content in lipid-rich myxoid liposarcomas with MRI: a single-center experience with survival analysis.

OBJECTIVE: To determine the fat content of myxoid liposarcomas (MLS) on MRI and to identify any association between lipid content and survival. MATERIALS AND METHODS: The fat percentage of MLS diagnosed between January 2006 and December 2016 at a single institution was assessed by two radiologists on preoperative MR images. A Cox proportional hazard model was used to determine any association between tumor fat percentage and survival time. Tumor fat percentage was the single predictor in the model. A significance level of 0.05 was used. The Kaplan-Meier estimator was also used to provide a nonparametric estimate of the survivor function within the entire sample and within two patient subgroups consists of lipid-rich and lipid-poor tumors. Lipid-rich tumors were defined as any tumors showing more than 20% of fat on MRI. A 20% cutoff was determined arbitrarily. RESULTS: Of the 43 cases identified through retrospective review, 8 tumors demonstrated ≥10% fat on MRI, and 4 tumors demonstrated ≥20% fat (highest fat percentage, 38%). There was no significant survival difference between patients with high tumor fat, which was defined as ≥20% fat, compared with those with little to no tumor fat. CONCLUSION: Myxoid liposarcomas may demonstrate a higher fat content on MRI than has previously been reported in the literature. Increased tumor fat percentage in lipid-rich tumors was not found to be associated with increased risk of death. Radiologists must be aware of the existence of MLS lesions with higher fat content.

CT-guided percutaneous biopsy of sclerotic bone lesions: diagnostic outcomes.

OBJECTIVE: To determine the diagnostic yield of CT-guided percutaneous biopsy of densely sclerotic bone lesions. MATERIALS AND METHODS: We retrospectively analyzed CT-guided percutaneous bone biopsies performed at our institution from September 2008 through August 2011 (329 cases) and from September 2012 through August 2015 (324 cases) after adoption of a battery-powered drill system (OnControl). Bone lesions were included in the analysis if they were >70% sclerotic by visual inspection, had a density > 2 times that of adjacent trabecular bone, and had an attenuation of ≥250 HU. Pathological fractures, diskitis-osteomyelitis, and osteoid osteomas were excluded. Eligible cases were characterized by lesion location, maximum lesion diameter, mean density, biopsy needle type and gauge, reported complications, and histological diagnosis. Clinical and imaging follow-up was used to confirm histological diagnosis. Cases in which a benign histological diagnosis could not be confirmed by imaging over a minimum period of 1 year were excluded. RESULTS: A total of 37 biopsies of sclerotic bone lesions met the inclusion criteria, 17 of which were performed with a power drill needle and 20 of which were performed with a manually driven needle. The mean lesion density was 604.1 HU. The overall diagnostic yield was 78.4%; overall diagnostic accuracy was 94.6%, and the false-negative rate was 5.4%. Diagnostic yield and accuracy were 82.4% and 100% respectively, with a power drill and 75% and 90% respectively, with a manual device. Diagnostic yield for lesions ≥700 HU was 90% (9 out of 10). CONCLUSION: Densely sclerotic bone lesions are amenable to percutaneous needle biopsy.

Radiation-induced focal cortical necrosis of the femur presenting as a lytic lesion.

Management of soft tissue sarcomas is often complicated, requiring radiation before and in some cases after limb-sparing surgery. Radiation necrosis is a severe complication after radiation treatment and is typically dose related and involves medullary bone. We report on two cases of hitherto unreported focal circumscribed intra-cortical lytic lesions within the radiation portal, which appeared 19 months and 31 months, respectively, after the conclusion of radiation treatment. Both patients had a history of soft tissue sarcoma treated with radiation (66 Gy) and surgical resection. Biopsy of these lesions showed necrotic bone attributed to radiation.

Osteoid osteoma of the hand and foot in children successfully treated with radiofrequency neurotomy probes.

Osteoid osteoma is a common benign tumor that is typically found in young adults and children, usually in the long bones of the lower extremity. Radiofrequency ablation (RFA) under computed tomography guidance is the standard of care for symptomatic osteoid osteomas. However, patients with osteoid osteoma of the hand or foot are often treated with open surgery because of the risk of injury to vascular and neural structures from RFA. This risk is more pronounced in pediatric patients because of the small lesion size and proximity of lesions to important neurovascular structures. Here, we present 2 pediatric patients, one with an osteoid osteoma in the hand and the other with an osteoid osteoma in the foot. In both patients, a 22-gauge, 2.5-mm active tip ablation probe was used. The smaller ablation volume achieved with this probe protected neighboring neurovascular structures while effectively ablating the osteoid osteoma nidus. Based on our success in these cases, we recommend the application of this method for cases in which neurovascular proximity to the osteoid osteoma lesion makes ablation challenging.

Air-blocking ablation of osteoid osteoma; a technical note.

Osteoid osteoma accounts for approximately 10-12% of all benign bone tumors. Surgery was the treatment of choice for osteoid osteomas until percutaneous radiofrequency ablation (RFA) was introduced in 1992. Although RFA is generally considered curative in the treatment of osteoid osteoma, disease recurrence after ablation has been reported. We report a case in which RFA was delayed by the presence air surrounding the ablation probe. In this case, ablation could only be performed after the probe was removed and saline was injected through the introducer needle to displace the air. Air is reported to decrease radiofrequency energy transmission; a simple measure like injecting saline through an introducer could prevent such a complication. We also suggest that partial air in the ablation bed surrounding the ablation probe could decrease the energy transmission and may be one of the causes of early recurrences. Saline injection could be helpful in providing a more reliable environment for ablation.