Dual-isotope SPECT/CT impact on hospitalized patients with suspected diabetic foot infection: saving limbs, lives, and resources.

BACKGROUND: Foot ulcer with suspected infection is one of the most common reasons for hospitalization and a major factor contributing to morbidity and high healthcare-related expenses among diabetic patients. Many patients will require amputation; however, major amputation is associated with an alarmingly high 5-year mortality rate. In this study, we assess the diagnosis and management of suspected foot infection in diabetic patients using dual-isotope (DI) single-photon emission computed tomography/computed tomography (SPECT/CT) compared with conventional imaging. METHODS: The diagnostic accuracy in and management of 227 patients who had undergone DI SPECT/CT was compared with that of 232 similar patients who had undergone conventional imaging including plain radiography, CT, planar bone scanning, planar indium-111 white blood cell scanning, and MRI. The duration of hospitalization was additionally compared between these two groups of patients after excluding patients with other active comorbidities. RESULTS: Soft-tissue infection, osteomyelitis with or without soft-tissue infection, and other bony pathologies were more accurately and confidently identified with DI SPECT/CT than with conventional imaging. DI SPECT/CT use was associated with significantly fewer major amputations and more selective bony resection as well as with shorter duration of hospitalization when compared with conventional imaging. CONCLUSION: In this large population of diabetic patients with suspected foot infection DI SPECT/CT was more accurate in diagnosing and localizing infection compared with conventional imaging. In addition, DI SPECT/CT provided clear guidance and promoted many limb salvage procedures. Of equal importance to health economics, DI SPECT/CT use was associated with considerably reduced length of hospitalization compared with conventional imaging.

The optimized evaluation of diabetic foot infection by dual isotope SPECT/CT imaging protocol.

Sequential Tc-99m hydroxymethylene-diphosphonate (HDP) 3-phase bone (BS) and In-111 leukocyte scanning (WBCS) have been frequently used to evaluate the diabetic foot, as nonosteomyelitis BS uptake is repeatedly observed and osteomyelitis (OM) in WBCS is often uncertain without BS correlation. Additionally, both modalities are limited in lesion localization because of low resolution and lack of anatomic details. We investigated a method that combined BS/WBCS, and if needed, WBCS/bone marrow scanning (BMS) using SPECT/CT to accurately diagnose/localize infection in a practical protocol. Blood flow/pool images were obtained followed by WBC reinjection and next day dual isotope (DI) BS/WBCS planar and SPECT/CT. BMS/WBCS SPECT/CT (step 2 DI) was obtained on the following day when images were suspicious for mid/hindfoot OM. Diagnosis accuracy and confidence were judged for the various imaging combinations. Diagnosis was classified as OM, soft tissue infection (STI), both OM/STI, and other/no bony pathology by microbiology/pathology or follow-up. Distinction between various diagnostic categories and overall OM diagnostic accuracy in 213 patients were higher for DI than WBCS or BS alone, and for DI SPECT/CT than DI planar or SPECT only. Diagnostic confidence/lesion site was significantly higher for DI SPECT/CT than other comparative imaging methods. In a group of 97 patients with confirmed microbiologic/pathologic diagnosis, similar results were attained. Step 2 DI SPECT/CT performed in 67 patients further improved diagnostic accuracy/confidence. DI SPECT/CT is a highly accurate modality that considerably improves detection and discrimination of STI and OM while providing precise anatomic localization in the diabetic foot. This combined imaging technique promises to beneficially impact diabetic patient care.