The Effect of Body Mass Index on Fluoroscopic Time and Radiation Dose During Intra‐articular Hip Injections

Fluoroscopy-guided aspiration of the acutely dislocated total hip arthroplasty: a feasible, high-yield, and safe procedure

OBJECTIVE

To determine the feasibility, yield, and safety of fluoroscopic-guided aspiration of the acutely dislocated total hip arthroplasty (AD-THA).

MATERIALS AND METHODS

IRB-approved, retrospective review of fluoroscopic-guided aspirations of AD-THA (January 2005-December 2023) was performed. Data from electronic charts and fluoroscopy images/reports were obtained. Positive yield was defined as spontaneous aspirate or saline rinse adequate for microbiology analysis. Sub-analysis by needle target (acetabular cup or femur) was performed for spontaneous aspiration rate, aspirate volume and fluoroscopy time. Differences between groups were analyzed with unpaired, t-test (2-tail) and between proportions with Fisher's exact test, with significance p < 0.05.

RESULTS

Aspiration of 20 AD-THA in 19 patients (12 female, mean age (SD) of 73 years (16)) targeted the acetabular cup in 45% (9/20) or femur in 55% (11/20) of cases. Positive yield was obtained in 95% (19/20), with spontaneous aspirate in 75% (15/20) and saline rinse in 20% (4/20) of cases; in 5% (1/20), no diagnostic sample was obtained. Spontaneous aspirate mean volume (SD, range) for all cases was 8.3 mL (6.9, 0.2-25), and higher when targeting the acetabular cup 11.2 mL (6.9, 5-25) versus the femur 4.0 mL (4.4, 0.2-12) (p = 0.026). The rate of spontaneous aspiration was higher for the acetabular cup 100% (9/9) versus the femur 55% (6/11) (p = 0.038). The mean fluoroscopy time (SD, range) for all cases was 43 s (25, 19-102), and shorter for targeting the acetabular cup 32 s (16, 19-75) versus the femur 56 s (28, 28-102) (p = 0.034). No immediate complications occurred in all aspirations.

CONCLUSION

Fluoroscopy-guided aspiration of AD-THA is a feasible, high-yield, and safe procedure. Targeting the acetabular cup results in a higher rate of spontaneous aspirate, larger aspiration volume, and lower fluoroscopy time.

CRITICAL RELEVANCE STATEMENT

Although technically more challenging, radiologists should feel confident aspirating the acutely dislocated total hip arthroplasty (AD-THA) under fluoroscopic guidance.

KEY POINTS

Total hip arthroplasty (THA) infection can be evaluated with synovial fluid aspiration. Fluoroscopic-guided aspiration of the dislocated THA is feasible, high-yield, and safe. Targeting of the acetabular cup is recommended over the femoral prosthetic component. Acetabular cup targeting gives larger, spontaneous aspirates with lower fluoroscopy time.

An audit of patient radiation doses in interventional radiology at a South African hospital

Background

Interventional radiology (IR) is becoming more relevant in patient care and is associated with increased patient radiation exposure and radiation-induced adverse effects. Diagnostic reference levels (DRLs) are crucial for radiation control. There is a paucity of published DRLs for IR in South Africa and sub-Saharan Africa.

Objectives

This study aimed to determine local DRLs for fluoroscopically-guided IR procedures and compare the achieved DRLs with published local and international DRLs.

Method

Retrospective, descriptive, single-centre study. Kerma air product (KAP), reference point air kerma (K_a,r) and fluoroscopy time (FT) were collected for patients (12 years and older) who underwent IR procedures at a university hospital from 01 January 2019 to 31 December 2019. The 75th percentile of the distribution of each dose parameter (KAP, K_a,r and FT) per procedure was calculated and taken as the local diagnostic reference levels (LDRL). The established LDRLs were compared to published DRLs.

Results

A total of 564 cases were evaluated. The 13 most frequent procedures (with 15 or more cases) represented 86.1% (487/564). Percutaneous transhepatic biliary drainage was the most common procedure (n = 146, 25.9%). Diagnostic cerebral angiogram DRLs exceeded the published DRL data ranges for all parameters (DRL 209.3), and interventional cerebral angiogram exceeded published ranges (DRL 275). Uterine artery embolisation (UAE) exceeded these ranges for KAP and K_a,r. (KAP-954.9 Gy/cm², K_a,r-2640.8 mGy).

Conclusion

The LDRLs for diagnostic cerebral angiogram, interventional cerebral angiogram and UAE exceeded published international DRL ranges. These procedures require radiation optimisation as recommended by the International Commission on Radiological Protection (ICRP).

Contribution

In addition to informing radiation protection practices at the level of the institution, the established LDRLs contribute towards Regional and National DRLs.

Hip aspiration: A comparison of ultrasound and fluoroscopic guidance

Introduction

Hip aspirations are commonly performed for diagnostic purposes using either fluoroscopic or ultrasound guidance. The superiority of one type of image guidance over another for aspiration of a native or replaced hip remains a matter of debate. The questions to be evaluated in this study include 1) to determine if hip aspiration using fluoroscopy or ultrasound guidance more often obtains fluid from native and post-arthroplasty hip joints, and 2) to identify patient-related factors associated with the ability to obtain fluid.

Material and methods

A retrospective analysis of all hip aspirations (433) performed at a single institution was undertaken, with the primary outcome variable being successful attainment of joint fluid. Age, body mass index (BMI), sex, presence of a trainee, presence of an arthroplasty at the time of aspiration on the affected side, amount of fluid collected, and type of image guidance were used as independent variables in regression models.

Results

1) The likelihood of obtaining fluid was approximately 2.1 times greater with ultrasound guidance than fluoroscopy guidance (95% CI = 1.382, 3.117; p < 0.001). 2) Ultrasound guidance and lower BMI were independently associated with a significantly higher likelihood of obtaining fluid. Additionally, one unit decrease in BMI was associated with about a 3% increase in the odds of obtaining fluid (95% CI = 0.950, 0.998; p = 0.033).

Conclusion

This study demonstrates that the use of ultrasound guidance for hip joint aspiration, when compared to fluoroscopic guidance, is more likely to result in a successful aspiration and the acquisition of a greater volume of fluid. Therefore, ultrasound guidance is the preferred method for hip aspiration in both native and replaced hips.

Intra-articular Hip Injection Using Anatomical and Radiological Landmarks Without the Use of Ultrasound or Radiological Guidance

INTRODUCTION

Intra-articular hip injections are routinely performed under sonographic or fluoroscopic guidance in order to improve accuracy. The purpose of this study was to evaluate the safety and accuracy of a hip injection technique that does not require the use of fluoroscopic or ultrasound guidance and can be performed in the clinic. A combination of radiographic and anatomic landmarks was used in order to perform the hip injection, based on the use of simple hip radiographs.

METHODS

In this prospective study 35 patients with hip osteoarthritis or femoroacetabular impingement were included. All patients underwent intra-articular hip joint injection using the technique we describe. The injection location was determined based on measurements performed on hip radiographs using as reference points fixed anatomical landmarks, i.e., the anterior superior iliac spine (ASIS), the cephalic, and caudal femoral head-neck junctions. The vertical distance between the ASIS and the greater trochanter and the horizontal distance between the two head-neck junctions, and the vertical line were also measured. The accuracy of the injection was assessed using ultrasound examination before and after the injection in order to verify intra-articular fluid injection.

RESULTS

Intra-articular hip joint injections using the described non-guided technique were successful in 33 of 35 (94.3%) patients without any complications.

CONCLUSION

 Hip injections can be performed with high accuracy without the need for radiological or ultrasound guidance using the described technique. The combination of radiological and anatomical landmarks to perform intra-articular hip injections is safe, cost-effective, and accurate.

What factors affect fluoroscopy use during Bernese periacetabular osteotomy for acetabular dysplasia?

Periacetabular osteotomy (PAO) is the treatment of choice for acetabular dysplasia in the skeletally mature. Little is known about factors affecting fluoroscopy use in PAO. Therefore, we strived to determine patient and surgery factors are associated with the amount of fluoroscopy time and radiation dose during PAO. We performed a retrospective review of 378 patients who underwent PAO between January 2012 and August 2017. The mean age was 21.7 years and 326 (86%) were females. A total of 85 patients underwent concomitant arthroscopy and 60 underwent open arthrotomy. We recorded fluoroscopy time in minutes and radiation dose area product (DAP) in mGy·m². Multivariate general linear modeling identified independent predictors of fluoroscopy time and radiation dose. Mean fluoroscopy time was 1.21 minutes and mean fluoroscopy DAP was 0.71 mGy·m². Multivariate predictors of increased fluoroscopy time were male gender (P = 0.001), surgeon (P < 0.001) and whether an arthroscopy was performed (P < 0.001). Multivariate predictors of increased fluoroscopy DAP were increased body mass index (BMI) (P = 0.001), surgeon (P < 0.001) and whether an arthroscopy was performed (P < 0.001). Patients undergoing hip arthroscopy concomitant to PAO are at higher risk of longer fluoroscopy time and higher radiation dose. Other factors affecting fluoroscopy time included male gender and surgeon, while radiation dose was further affected by surgeon and BMI. Our findings can facilitate discussion about the risk of radiation exposure during PAO.

Improved Dose Estimates for Fluoroscopically Guided Lumbar Epidural Injections

OBJECTIVE

The goal of the study was to determine the potential impact of system inaccuracies and table attenuation on fluoroscope-reported dose values.

DESIGN

An Institutional Review Board-approved study was conducted to collect detailed acquisition and patient exposure data for fluoroscopy-guided lumbar epidural injections.

BACKGROUND

System-reported dosimetry values, especially the air Kinetic Energy Released per unit MAss and dose-area product metrics, are routinely used for estimating the radiation burden to patients undergoing fluoroscopy-guided procedures. However, these metrics do not account for other factors, such as acquisition geometry, where the table may attenuate a substantial fraction of the x-ray intensity, and system dosimetry inaccuracies, which are only required to be accurate within ±35%.

METHODS

Acquisition data from 46 patients undergoing fluoroscopy-guided lumbar epidural injections were collected to better estimate the true incident dose-area product. Gantry angles, x-ray technique factors, and field sizes were collected to characterize each procedure. Additionally, the fluoroscope dosimetry accuracy and table attenuation properties were evaluated as a function of kVp to generate the correction factors necessary for accurate dosimetry estimates.

RESULTS

The system-reported values overestimated the total patient entrance dose-area product by an average of 34% (13-44%). Errors may be substantially higher for systems with less accurate fluoroscopes or more anterior-posterior projections. Correcting system-reported dosimetry values for systematic inaccuracies and variability can substantially improve fluoroscopic dose values.

CONCLUSIONS

Including corrections for system output inaccuracies and acquisition factors such as table attenuation is necessary for any reliable assessment of radiation burden to patients associated with fluoroscopy-guided procedures.

Increased radiation dose and projected radiation-related lifetime cancer risk in patients with obesity due to projection radiography

PURPOSE

Primarily to evaluate the radiation dose delivered to patients with obesity in projection radiography and its relationship to the patient's size. A secondary purpose is to estimate the subsequent projected radiation-related lifetime cancer risk to patients with obesity compared to normal-weight patients.

METHOD AND MATERIAL

Data from 1964 patients from a bariatric clinic in the UK were reviewed with the relevant permission. 630 patients were identified to have a projection radiography history and were included in the study. Patients' dose area product (DAP) data were collected for all projection radiography. Multiple exams in one day including a single DAP reading and exams with no records of DAP and exposure factors were excluded. Correlations were calculated and data analysed to yield the third quartile for each examination using STATA 14. Absorbed doses were generated from PCXMC simulation, utilising DAP data from this study and the UK national diagnostic reference level (NDRL), to calculate the effective risk for patients with obesity compared to patients with normal-weight.

RESULTS

Patients with obesity received higher DAPs for all examinations included in this study compared to NDRL. Abdominal and lumbar spine radiographs DAPs were the highest (17.6 and 30.31 Gy cm²) compared to the NDRL (2.5 and 4 Gy cm²). Only moderate to low correlations were found between patient's size and DAPs in the abdomen and chest radiographs. The projected radiation-related lifetime cancer risk for patients with obesity is up to 153% higher than for adult patients with normal weight.

CONCLUSION

Patients with obesity receive higher DAPs than normal-weight adults which may be in excess of that expected due to their size. Therefore, radiation-related lifetime cancer risk is increased in patients with obesity as a result of medical radiation exposures. This indicates more dose optimisation research is needed in this group of patients to reduce dose rate and variation.

Intraoperative Arthrographic Assessment of Ambiguous Neck of Femur Fractures in Patients With Chronic Kidney Disease

The loss of bone mineral density caused by Chronic Kidney Disease can make the delineation of a patient’s bony anatomy impossible during intra-operative fluoroscopy. This has the potential to increase the failure rate of implants used in the surgical treatment of neck of femur fractures due to sub-optimal placements. Intra-operative arthrograms add to the techniques available to a surgeon to achieve optimal implant placement without compromising the patient’s renal function nor increasing the radiation dose exposure to the surgical team.

Is There a Relationship Between Body Mass Index and Fluoroscopy Time During Cervical Interlaminar Epidural Steroid Injections?

Background

The challenge of obtaining medical imaging in individuals with higher body mass index (BMI) is described, but there is minimal data regarding the relationship between BMI and fluoroscopy time during cervical interlaminar epidural steroid injection (CIESI).

Objective

To determine the relationship between BMI and fluoroscopy time during CIESI.

Methods

Retrospective cohort study of patients who underwent fluoroscopically guided CIESI between January 2014 and February 2015 at an academic pain medicine center. Fluoroscopy time data were collected. Comparisons based on analysis of variance were made between patients with normal (<25.0 kg/m 2 ), overweight (25.0-29.9 kg/m 2 ), and obese (≥30.0 kg/m 2 ) BMI.

Results

Of 399 procedure encounters, 366 had documented BMI and fluoroscopy time data and were included for analysis. Mean age (± SD) in this cohort was 53 ± 13 years, including 189 females (52%) and 205 first-time injections. Mean fluoroscopy time for all injections was 18 ± 10 seconds. Separated by categorical BMI class, the mean fluoroscopy time was 18 ± 9 seconds for normal weight patients, 17 ± 10 seconds for overweight patients, and 20 ± 11 seconds for obese patients, respectively. Post hoc analysis showed that fluoroscopy time was significantly longer only in obese compared with overweight patients ( P  = 0.02). Trainee involvement and first-time vs repeat injection did not significantly alter fluoroscopy time ( P  = 0.17 and P  = 0.12, respectively).

Conclusions

The findings of this study indicate that BMI does not appear to have a clinically significant impact on fluoroscopy time during cervical interlaminar epidural steroid injection procedures. Future study is needed to directly quantify radiation exposure in patients and practitioners, as well as the associated health risk.

Comparison of lumbosacral transforaminal epidural steroid injection techniques in terms of radiation safety

Aim: To investigate the difference in radiation exposure to the patients between oblique and posteroanterior view, initial approach techniques in fluoroscopy-guided lumbosacral transforaminal epidural steroid injections. Patients & methods: Total amount of Kerma area product, elapsed time of the procedure and fluoroscopy time were obtained from medical records retrospectively. Results: 28 patients were included in each group. Fluoroscopy time was significantly lower in group 1, but there was no statistically significant difference in terms of procedure time and Kerma area product. Conclusion: Radiation risk does not change between these approaches.

The effect of body mass index on fluoroscopic time and radiation dose during lumbar transforaminal epidural steroid injections

OBJECTIVE

Transforaminal epidural steroid injections (TFESIs) are a commonly used, effective treatment for radicular pain. Accurate delivery of the injected medication helps to ensure maximum therapeutic efficacy and to decrease possible adverse events, and fluoroscopy is the preferred and most common image-guidance modality used to ensure accurate needle placement during lumbar TFESIs. However, fluoroscopic-guided lumbar TFESIs put patients at risk because of radiation exposure. The purpose of this study was to determine the relationship between body mass index (BMI) and fluoroscopy time and radiation dose during lumbar TFESIs.

DESIGN

A retrospective study design was used.

SETTING

The study was conducted at an academic orthopedic center. All procedures were performed by physicians board-certified in Physical Medicine and Rehabilitation (PM&R) and with subspecialty certification in sports medicine, or by a trainee under close supervision from an attending physician.

PARTICIPANTS

Participants were patients who underwent fluoroscopic-guided lumbar TFESIs between February 2013 and March 2015 with a documented height/weight, fluoroscopy time, and radiation dose.

INTERVENTIONS

All patients received unilateral or bilateral lumbar TFESIs with fluoroscopic guidance. Fluoroscopy time and dose were recorded.

MAIN OUTCOME MEASURES

The main outcome measures were fluoroscopy time and radiation dose. A Bonferroni correction was implemented for multiple comparisons, defining statistical significance at p<.01.

RESULTS

A total of 2,443 injections were performed on 1,548 patients. There were 419 normal, 572 overweight, and 557 obese patients, respectively. There were 1,426 first-time injections and 1,017 repeat injections. Sixty-nine percent (1,681) were unilateral injections, and 26.4% (645) were single level injections. A trainee was involved in 1,361 (55.7%) of the injections performed. The mean fluoroscopy time for all injections was 30.0±17.5 seconds, and the mean radiation dose was 2,164±1,484 mGy-cm(2). The mean fluoroscopy time was 27.7±15.2 seconds for normal weight patients, 30.0±21.0 seconds for overweight patients, and 32.2±15.1 seconds for obese patients, showing a significant difference between groups (p<.001). The mean radiation doses for each group were 1,376±450, 1,911±653, and 3,029±640 mGy-cm(2), respectively, with a significant increase in radiation dose with increasing BMI (p<.001).

CONCLUSIONS

The findings of this study demonstrate that fluoroscopy radiation dose and fluoroscopy time during lumbar TFESIs are increased in patients with an elevated BMI, and in patients of greater age, but the presence of a trainee had no effect on fluoroscopy time.