Diagnostic Value of Early phase Tc99m MDP SPECT/CT in Patients with Suspected Osteomyelitis

 

 

 

 

 

DISCUSSION

The current work assessed the diagnostic quality of early-stage Tc-99m methyldiphosphonate (MDP) SPECT/CT in suspected osteomyelitis patients and it was found that, the diagnostic quality level was high with a sensitivity of 90.8, specificity of 83.3 and an overall diagnostic score of 87.2. These results indicate that early-stage SPECT/CT is also a dependable imaging modality which not only remains as sensitive as nuclear medicine methods commonly used, but also offers a great deal of specificity over the traditional three-phase bone scintigraphy (TPBS). The quality of a CT/SPECT that can distinguish better between bone and soft tissue involvement at the early stages of the disease seems to be the most significant factor behind its performance in diagnosing.

Findings of the current study align with the recent developments in the hybrid imaging methods that are proving to have better diagnostic results over the traditional imaging modalities. In a multicenter, retrospective and large study, Gao et al. [11] found that Tc-99m MDP SPECT/CT had a sensitivity and specificity of 96 percent and 92 percent, respectively, with a total diagnostic efficiency of 96 percent. These values are marginally above those reported in the current study although the difference is perhaps due to the different study design, population of the patients involved and the applied complex quantitative reconstruction techniques. However, the two studies both indicate that the hybrid form of SPECT/CT imaging is definitely superior to the traditional forms of imaging like MRI and planar scintigraphy, especially in the specificity and diagnostic certainty.

Osteomyelitis is another disease that has received a boost diagnostic power using quantitative SPECT/ CT imaging. The sensitivity and specificity reported as well over 90% with quantitative parameters including standardized uptake value (SUVmax) and infection /background ratio (Nishikawa et al. [12]). In comparison to such results, a relatively less specificity in the case of the current study could be attributed to the qualitative aspect of image interpretation. Nonetheless, the protocol used in the early phases of acquisition in this study has a practical benefit as it allows a better visualization of the activity of perfusion and blood pools without involving the use of a complex quantitative analysis. This indicates that the early-stage SPECT/CT could be viable and applicable in a normal clinical scenario where sophisticated quantitative instruments might be unfamiliar.

Alternative imaging modalities Hybrid imaging modalities like FDG-PET/MRI have also been investigated in the investigation of osteomyelitis. The results by Hulsen et al. [13] indicated that FDG-PET/MRI had a specificity of 100% and a comparatively low sensitivity of 78% in the diagnosis of chronic osteomyelitis. Comparatively, the first stage SPECT/CT of the present study was more sensitive, which suggests that it has a larger capacity of identifying the actual cases of infection. Nevertheless, the reduced specificity of SPECT/CT than PET/MRI can imply that early-stage SPECT/CT is beneficial in detecting disease, whereas the PET-based interests can be more efficient in verifying disease in the absence of false-positive results. Nonetheless, PET/MRI is not as universally accessible and is more expensive which limits its application, especially in resource-limited facilities.

Traditional imaging modalities remain a part of the diagnostic pathway and are linked to significant drawbacks. Foti et al. [14] showed that MRI had a sensitivity and specificity of 89.1 and 87.5, respectively and dual-energy CT (DECT) had a similar sensitivity but poorer specificity. The results of the current study show that early-stage SPECT/CT has the same sensitivity to MRI but a bit lower specificity. But as compared to MRI, SPECT/CT is capable of giving functional data which can enhance confidence of diagnosis particularly in cases with indeterminate anatomical results or postoperative alterations.

Mishra et al. [15] found that MRI got a high sensitivity level (96%) and a significantly low specificity level (38.2) in diabetic foot osteomyelitis whose diagnostic challenges are especially great. This underscores how MRI is likely to overdiagnose infection because of the challenge of differentiating between infection, inflammation or neuropathic alterations. By comparison, the present study with early-stage SPECT/CT had much higher specificity and PPV, indicating that there is a lower chance of false-positive diagnosis. It has clinical implications because over diagnosis can result in unnecessary therapy with antibiotics or even surgery.

The examination of biomarker-based methods has been examined in diagnosing osteomyelitis, as well. Soleimani et al. [16] gave a report of good diagnostic accuracy by means of procalcitonin levels with the sensitivity and specificity of nearly 100 percent. Likewise, Sun et al. [17] showed the neutrophil CD64 index with erythrocyte sedimentation rate was highly diagnostic. Although these are encouraging results, these biomarkers do not have the capacity to localize infection hence they cannot substitute imaging modalities. Rather, they can be of as an effective supplement to imaging, especially in complicated instances when both clinical and imaging results are indeterminate.

The new imaging technologies, such as radiomics and other more advanced MRI parameters, have proven themselves as having potential in enhancing the diagnostic accuracy. According to The et al. [18], apparent diffusion coefficient (ADC) ghost sign exhibited high specificity (94.5%), but low sensitivity (19.5%), which shows that it is not a useful diagnostic sign alone. Jia et al. [19] have shown that MRI-based radiomics could increase diagnostic performance and help in surgery decision-making. In the same way, Shin et al. [20] have found that quantitative SPECT/CT uptake ratios had moderate sensitivity (71.4%) and high specificity (88.9%). Such results indicate that quantitative or radiomic methods of integration with early-stage SPECT/CT further improve its diagnostic capabilities.

The probe-to-bone (PTB) test along with plain radiography, have demonstrated low diagnostic accuracy. Herrera-Casamayor et al. [21] found that the PTB test with biomarkers or radiography yielded moderate sensitivity (~75) and very low specificity (~2324%). Such results are vastly poorer compared to findings with early-grading SPECT/CT in the current research and support the significance of high-level imaging to establish the diagnosis of osteomyelitis. On the same note, Xu et al. [22] and Coye et al. [23] pointed out that the primary intention of inflammatory markers and bedside tests is to be used as a screening tool but not a pathogenic test.

Research that has been conducted on individual parts of the body further demonstrates the inconsistency of the diagnostic accuracy of differing modalities of imaging. Muraoka et al. [24,25] also proved the usefulness of diffusion-weighted MRI in the diagnosis of mandibular osteomyelitis and Kawasaki et al. [26] showed a high level of sensitivity when it comes to some radiographics (e.g., osteosclerosis and bone resorption) but a low level of sensitivity of detecting sequestration and cortical per These results underline that anatomical imaging can be unsuitable to assess all the elements and justify the contribution of hybrid imaging methods that help to integrate functional with structural data.

The better diagnostic quality of the early-stage SPECT/CT as is the case of the current study may be explained by the fact that it can trace the distribution of the tracers during the blood pool phase and localize anatomically. This has the benefit of enhanced distinction of hyperemia in soft tissues and actual bone involvement, a frequent source of diagnostic uncertainty in planar imaging. Early-phase SPECT/CT obviates the chances of a false-positive interpretation caused by a lag in tracer uptake in noninfectious states, by observing initial inflammatory changes.

Limitations

In spite of merits, the current study is limited in the following ways. To begin with, the study was carried out in one center which can restrict the generalization of the findings. Second, the interpretation of the images was carried out qualitatively, and quantitative parameters were not involved, which might improve diagnostic accuracy. Third, the histopathology was the gold standard but not all patients are likely to have done biopsy, which risks introducing verification bias. Further research with multicenter data and quantitative imaging is justified to confirm and further generalize these findings.

 

CONCLUSION

To sum up, the results of the current work indicate that Tc-99m MDP SPECT/CT at an early stage is an effective diagnostic instrument that can be used in the assessment of suspected osteomyelitis. It is a balanced profile with the highest sensitivity and better specificity than the traditional imaging modalities. In comparison with recent literature, primitive stage SPECT/CT has a competitive performance on the advanced imaging methods, and does have a feasible, convenient, and quality way of clinical utility in routine applications. Its high sensitivity to minimise false positive diagnoses and its high diagnostic confidence makes it especially effective when it comes to complex clinical situations such as postoperative and post-traumatic. Future studies with quantitative measure and more patient’s cohort could be used to further improve its application in clinical practice.

Recommendations

Tc-99m MDP SPECT/CT is a Tc-99m based imaging modality that is advised to be used as an adjunct imaging in patients with suspected osteomyelitis when the planar three-phase bone scintigraphy are equivocal. It has a better specificity and sensitivity that increases its usefulness in proper diagnosis and minimizing the false-positive results. It must be included into the routine imaging protocols in tertiary care cases, and when dealing with complex cases, like postoperative, post-traumatic, and diabetic foot infections. Combination with clinical and laboratory data should be encouraged to improve the overall precision of diagnosis. Interpretation standards and training should be standardized to bring uniformity across institutions. The future of the multicentric research with increased sample size and quantitative imaging parameter inclusion is desirable in order to substantiate its diagnostic roles further. Moreover, the research assessing its effectiveness concerning treatment monitoring and cost-efficiency is proposed to facilitate its further clinical implementation.

 

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