Valor de la gammagrafía de médula macrofágica en el diagnóstico de infección de prótesis total de cadera estudiada con leucocitos 99mTc-HMPAO

Dual-tracer approach vs. dual time-point approach in leukocyte scintigraphy in treatment evaluation of persistent chronic prosthetic joint infection

BACKGROUND

Both dual time-point 99mTc-hexamethylpropylene amine oxime (HMPAO)-leukocyte scintigraphy and dual-tracer 99mTc-HMPAO-leukocyte scintigraphy (with the addition of 99mTc-nanocolloid bone marrow scintigraphy) have been used to diagnose prosthetic joint infection (PJI). A treatment evaluation of persistent PJI using these imaging protocols has yet to be presented.

OBJECTIVE

The purpose of this study was to compare the accuracy of dual time-point 99mTc-HMPAO-leukocyte scintigraphy to the dual-tracer alternative of single time-point 99mTc-HMPAO-leukocyte scintigraphy or single-photon emission computed tomography/computed tomography (SPECT/CT) combined with a 99mTc-nanocolloid bone marrow scintigraphy or SPECT/CT, for treatment evaluation of PJI.

MATERIAL AND METHODS

Thirty-one PJI patients under antibiotic treatment were included in this retrospective study. Examinations were organized into three settings. Setting one used dual time-point approach with delayed (2 h) and late (24 h) planar 99mTc-HMPAO-leukocyte scintigraphy, including both visual and semiquantitative analysis. Setting two used delayed (2 h) planar 99mTc-HMPAO-leukocyte scintigraphy combined with 99mTc-nanocolloid bone marrow scintigraphy and for setting three SPECT/CT replaced planar imaging.

RESULTS

Accuracy was 0.68 for visual evaluation and 0.55 for semiquantitative evaluation of setting one; 0.71 for setting two; and 0.68 for setting three. Sensitivity was 0.54 for visual evaluation and 0.31 for semiquantitative evaluation of setting one; 0.38 for setting two; and 0.46 for setting three. Specificity was 0.78 for visual evaluation and 0.72 for semiquantitative evaluation of setting one; 0.94 for setting two; and 0.83 for setting three.

CONCLUSION

No significant difference in accuracy, sensitivity, or specificity between the approaches for treatment evaluation of suspected persistent PJI in the hip or knee was observed.

Is 99mTc-HMPAO-leukocyte imaging an accurate method in evaluating therapy result in prosthetic joint infection and diagnosing suspected chronic prosthetic joint infection?

BACKGROUND

To investigate the sensitivity and specificity of 99mTc-HMPAO-leukocyte imaging in evaluating therapy result in patients with prosthetic joint infection (PJI) and in diagnosing suspected chronic PJI.

METHODS

Sixty-two patients (63 joints) with microbiologically verified PJI were examined by leukocyte imaging to evaluate therapy result during or at the end of antibiotic treatment or if the patient had a chronic PJI after treatment. Group 1 consisted of 49 patients with on-going or within less than 14 days of ending antibiotic treatment examined to evaluate response. Group 2 consisted of 13 patients examined after completed treatment on suspicion of chronic PJI with no or recently initiated renewed antibiotic treatment. This study applied a combination of different imaging approaches of 99mTc-HMPAO-leukocyte scintigraphy: delayed and late planar images, bone marrow imaging and SPECT/CT imaging. All joints were examined with at least two of the approaches and 53 joints with all three approaches. The report was based on the combined results of the approaches used. A chronic PJI was confirmed with a positive microbiological culture. A cured infection was confirmed with either a negative culture or at least 24 months antibiotic-free follow-up with no relapse.

RESULTS

In the therapy evaluation group sensitivity was 0.57 and specificity was 0.81. In the suspected chronic infection group sensitivity was 1.00 and specificity 0.91.

CONCLUSIONS

99mTc-HMPAO-leukocyte imaging appears to be an accurate method to diagnose or exclude chronic PJI, but cannot be recommended for therapy evaluation of PJI in patients with on-going antibiotic treatment.

The Accuracy of Imaging Techniques in the Assessment of Periprosthetic Hip Infection: A Systematic Review and Meta-Analysis

BACKGROUND

Various imaging techniques are used for excluding or confirming periprosthetic hip infection, but there is no consensus regarding the most accurate technique. The objective of this study was to determine the accuracy of current imaging modalities in diagnosing periprosthetic hip infection.

METHODS

A systematic review and meta-analysis of the literature was conducted with a comprehensive search of MEDLINE and Embase to identify clinical studies in which periprosthetic hip infection was investigated with different imaging modalities. The sensitivity and specificity of each imaging technique were determined and compared with the results of microbiological and histological analysis, intraoperative findings, and clinical follow-up of >6 months.

RESULTS

A total of 31 studies, published between 1988 and 2014, were included for meta-analysis, representing 1,753 hip prostheses. Quality assessment of the included studies identified low concerns with regard to external validity but more concerns with regard to internal validity including risk of bias (>50% of studies had insufficient information). No meta-analysis was performed for radiography, ultrasonography, computed tomography, and magnetic resonance imaging because of insufficient available clinical data. The pooled sensitivity and specificity were 88% (95% confidence interval [CI], 81% to 94%) and 92% (95% CI, 88% to 96%), respectively, for leukocyte scintigraphy; 86% (95% CI, 80% to 90%) and 93% (95% CI, 90% to 95%) for fluorodeoxyglucose positron emission tomography (FDG PET); 69% (95% CI, 58% to 79%) and 96% (95% CI, 93% to 98%) for combined leukocyte and bone marrow scintigraphy; 84% (95% CI, 70% to 93%) and 75% (95% CI, 66% to 82%) for antigranulocyte scintigraphy; and 80% (95% CI, 72% to 86%) and 69% (95% CI, 64% to 73%) for bone scintigraphy.

CONCLUSIONS

Of the currently used imaging techniques, leukocyte scintigraphy has satisfactory accuracy in confirming or excluding periprosthetic hip infection. Although not significantly different, combined leukocyte and bone marrow scintigraphy was the most specific imaging technique. FDG PET has an appropriate accuracy in confirming or excluding periprosthetic hip infection, but may not yet be the preferred imaging modality because of limited availability and relatively higher cost.

LEVEL OF EVIDENCE

Diagnostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

[Screening with angiographic images prior to (99m)Tc-HMPAO labelled leukocyte scintigraphy in the diagnosis of periprosthetic infection]

AIM

To evaluate the impact of the angioscintigrapy of the three phase bone scan as screening method to rule out infection of the hip and knee prosthesis prior to performing the (99m)Tc-HMPAO leukocyte scintigraphy.

MATERIAL AND METHODS

A total of 120 (70 women, 50 men; mean age 71±11years) with clinical suspicion of hip (n=63) or knee (n=57) infection of the prosthesis and clinical suspicion of infection were evaluated prospectively. All patients underwent three-phase bone scan (angioscintigraphy, vascular and bone phase) and (99m)Tc-HMPAO-labelled white blood cell scintigraphy. Final diagnosis of infection was made by microbiological documentation or clinical follow-up for at least 12months.

RESULTS

Eighteen out of 120 patients were diagnosed of infection of hip prosthesis (n=10) or knee prosthesis (n=8). The angioscintigraphy was positive in 15/18 infected cases and in 21/102 of the non-infected cases with a sensitivity of 83%, specificity of 79% and negative predictive value of 97%. Sensitivity and specificity of (99m)Tc-HMPAO leukocyte scintigraphy were 72% and 95%, respectively. If the leukocyte labeled scintigraphies had been used exclusively for patients with positive angioscintigraphy, this would have saved up to 70% of the (99m)Tc-HMPAO leukocyte scintigraphies performed. There were no cases of infection with positive labeled leukocyte scintigraphy and negative angioscintigraphy.

CONCLUSION

Angioscintigraphy (blood flow phase of bone scan) is a useful technique for screening for hip and knee joint prosthesis infection, significantly reducing the need for (99m)Tc-HMPAO leukocyte scintigraphy without affecting the sensitivity of the technique.

Usefulness of adding SPECT/CT to 99mTc-hexamethylpropylene amine oxime (HMPAO)-labeled leukocyte imaging for diagnosing prosthetic joint infections

OBJECTIVE

This study evaluated the usefulness of adding single-photon emission computed tomography (SPECT)/computed tomography (CT) (SPECT/CT) to technetium Tc 99m (Tc) hexamethylpropylene amine oxime (HMPAO)-labeled leukocyte imaging for diagnosing infections in hip or knee joint prostheses.

METHODS

The Tc-HMPAO-labeled leukocyte scans of 164 patients (71 with hip prostheses and 93 with knee prostheses) with clinically suspected prosthetic infections were reviewed retrospectively. Planar images were taken 4 to 6 and 21 to 26 hours after injecting the labeled leukocytes and SPECT/CT images were obtained 4 to 6 hours after the injection. The final diagnosis of infection was based on pathologic findings (n = 70), bacteriological data (n = 61), or clinical follow-up (n = 33).

RESULTS

Of the 164 patients, 89 patients had a diagnosis of prosthetic joint infections. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and diagnostic accuracy of the planar images alone were 82.0%, 88.0%, 89.0%, 80.5%, and 84.8%, respectively. When the planar images were combined with SPECT, the sensitivity, specificity, PPV, NPV, and diagnostic accuracy were 91.0%, 88.0%, 90.0%, 89.2%, and 89.6%, respectively. When the planar images were combined with SPECT/CT, these values increased further to 93.3%, 93.3%, 94.3%, 92.1%, and 93.3%, respectively. Adding CT to SPECT resulted in a greater increase in sensitivity and specificity for hip prosthesis infections than for knee prosthesis infections. SPECT/CT mainly contributed by precisely localizing the anatomical site of the active inflammatory lesion and by delineating the extent of the lesion after diagnosis with SPECT.

CONCLUSIONS

Single-photon emission computed tomography/CT combined with Tc-HMPAO-labeled leukocyte imaging was useful for diagnosing prosthesis infections, particularly in hip prosthesis infections, as it improved diagnostic accuracy and provided anatomical localization data.

One-stage revision arthroplasty for infected hip replacements

Infection remains a serious complication after total hip arthroplasty (THA) and is a leading cause of hip revision surgery. It is currently accepted that removal of the prosthesis is essential to curing an infection when facing chronic PJIs with prosthesis loosening. In order to avoid the disadvantages of a two-stage approach, some authors have proposed a one-stage hip revision for the treatment of hip prosthesis infection in selected patients using not only antibiotic-loaded cemented components but also cementless implant. In the case of a one-stage procedure, the patient is exposed to a single major procedure and therefore lower cumulative perioperative risk. A functional prosthesis replacement is completed without exposure to the complications associated with spacers. In addition, there are also benefits both financially and in terms of resource allocation.

Prosthetic joint infections: radionuclide state-of-the-art imaging

Prosthetic joint replacement surgery is performed with increasing frequency. Overall the incidence of prosthetic joint infection (PJI) and subsequently prosthesis revision failure is estimated to be between 1 and 3%. Differentiating infection from aseptic mechanical loosening, which is the most common cause of prosthetic failure, is especially important because of different types of therapeutic management. Despite a thorough patient history, physical examination, multiple diagnostic tests and complex algorithms, differentiating PJI from aseptic loosening remains challenging. Among imaging modalities, radiographs are neither sensitive nor specific and cross-sectional imaging techniques, such as computed tomography and magnetic resonance imaging, are limited by hardware-induced artefacts. Radionuclide imaging reflects functional rather than anatomical changes and is not hampered by the presence of a metallic joint prosthesis. As a result scintigraphy is currently the modality of choice in the investigation of suspected PJI. Unfortunately, there is no true consensus about the gold standard technique since there are several drawbacks and limitations inherent to each modality. Bone scintigraphy (BS) is sensitive for identifying the failed joint replacement, but cannot differentiate between infection and aseptic loosening. Combined bone/gallium scintigraphy (BS/GS) offers modest improvement over BS alone for diagnosing PJI. However, due to a number of drawbacks, BS/GS has generally been superseded by other techniques but it still may have a role in neutropenic patients. Radiolabelled leucocyte scintigraphy remains the gold standard technique for diagnosing neutrophil-mediated processes. It seems to be that combined in vitro labelled leucocyte/bone marrow scintigraphy (LS/BMS), with an accuracy of about 90%, is currently the imaging modality of choice for diagnosing PJI. There are, however, significant limitations using in vitro labelled leucocytes and considerable effort has been devoted to developing alternative radiotracers, such as radiolabelled HIGs, liposomes, antigranulocyte antibodies and fragments, as well as more investigational tracers such as radiolabelled antibiotics, antimicrobial peptides, bacteriophages and thymidine kinase. On the other hand, positron emission tomography (PET) is still growing in the field of PJI imaging with radiotracers such as (18)F-fluorodeoxyglucose (FDG), (18)F-FDG white blood cells and (18)F-fluoride. But unfortunately this superb tomographic technique will only receive full acceptance when specific PET uptake patterns can be successfully developed. The emergence of hybrid modality imaging using integrated single photon emission computed tomography (SPECT) and PET with computed tomography (SPECT/CT and PET/CT) may also have a contributing role for more accurate assessment of joint replacement complications, especially combined with new radiotracers such as (68)Ga and (64)Cu. Finally, in searching for infection-specific tracers, currently there is no such diagnostic agent available.

Usefulness of 99mTc-ciprofloxacin scintigraphy in the diagnosis of prosthetic joint infections. Nucl Med Commun. 2011;32:44-51. [PMID: 20975609 DOI: 10.1097/MNM.0b013e328340e6fb]

OBJECTIVE

To evaluate the usefulness of 99Tc-ciprofloxacin scintigraphy (CFS) in patients with hip or knee arthroplasty and suspected infection.

METHODS

Forty patients (26 women, 14 men) with a mean age of 66±10 years and local pain in the hip (21), knee (16), or shoulder (three) prosthesis were recruited. CFS was performed at 1, 4, and 24 h after intravenous injection of 370 MBq. Anterior and posterior views centered on the affected joint were performed in all patients. A routine bone scan, 99Tc-hexamethylpropyleneamine oxime leukocyte scan, and 99Tc-colloid scan [leukocyte scintigraphy-bone marrow scintigraphy (LS-MS)] were performed. Final diagnosis of infection was confirmed by positive microbiological analysis or macroscopic evidence of purulent material.

RESULTS

Diagnosis of arthroplasty infection was established in 16 out 40 cases: coagulase-negative staphylococci (nine), Staphylococcus aureus (three), Enterococcus (one), and macroscopic infection in the remaining three cases. CFS imaging showed the 24-h image to be the best acquisition time-point. The sensitivity, specificity, negative predictive value, and positive predictive value for LS-MS were 75, 92, 86, and 85%, whereas for CFS at 24 h these figures were 88, 71, 67, and 89%. The sensitivity and specificity for LS-MS and for CFS at 24 h for hip were (74, 90, and 88, 85%) and for knee (83, 90 and 100, 50%).

CONCLUSION

CFS can be useful in the diagnosis of arthroplasty infection of the hip as a substitute for LS-MS. It is recommended that CFS images be obtained 24 h after injection. The lack of specificity of CFS makes this technique inadequate for knee prostheses in this series.