Diagnostic imaging tests and microbial infections

Abstract

SummaryDespite significant advances in the understanding of its pathogenesis, infection remains a major cause of patient morbidity and mortality. While the presence of infection may be suggested by signs and symptoms, imaging tests are often used to localize or confirm its presence. There are two principal imaging test types: morphological and functional. Morphological tests include radiographs, computed tomography (CT), magnetic resonance imaging, and sonongraphy. These procedures detect anatomic, or structural, alterations produced by microbial invasion and host response. Functional imaging tests reflect the physiological changes that are part of this process. Prototypical functional tests are radionuclide procedures such as bone, gallium, labelled leukocyte and fluorodeoxyglucose (FDG)-positron emission tomography (PET) imaging. In-line functional/morphological tomographic imaging systems, PET/CT and single photon emission tomography (SPECT)/CT, have revolutionized diagnostic imaging. These devices consist of a functional imaging device (PET or SPECT) joined together with a CT scanner. The patient undergoes both tests sequentially without leaving the examination table. Images from each study can be viewed separately and as fused images, providing precisely localized anatomic and functional information. It must be noted, however, that none of the current morphological or functional tests, either alone or in combination, are specific for infection and the goal of finding such an imaging test remains elusive.

Magnetic Resonance Imaging Findings in Hematogenous Osteomyelitis of the Hip in Adults

“…However, intravenous contrast is not routinely used at our institution for the work-up of musculoskeletal infections. This is similar to suggestions by other authors [18,19], who reported that bone inflammatory changes were similar in extent on contrast-enhanced T1-weighted sequences and on fast fat-suppressed T2-weighted sequences, such as STIR. In our experience, abscesses are also clearly demonstrated on STIR sequences, but if there is difficulty distinguishing phlegmon from abscess, then contrast is used.…”

“…Bone scintigraphy can evaluate the whole skeleton for other areas of osteomyelitis, which can be useful in young children with diffuse symptoms, but does not provide anatomic detail and exact localization of the infectious process [4,24]. Ultrasound can diagnose fluid collections but cannot provide data on bone involvement [19]. Computerized tomography can delineate sequestra and diagnose fluid collections but does not provide the detail that MRI does on early marrow changes [12,17].…”

Bacterial infection imaging with [ 18 F]fluoropropyl-trimethoprim

“…T he distinction between bacterial infection and other disease entities such as sterile inflammation and cancer can be challenging on the basis of symptoms and physical findings. In addition, it is accepted that there can be significant overlap between bacterial infection, inflammation, and cancer using both standard diagnostic imaging techniques [e.g., computed tomography, contrastenhanced magnetic resonance imaging, and positron emission tomography (PET)] and laboratory studies (e.g., white blood cell count, erythrocyte sedimentation rate) (1,2). This lack of diagnostic feature specificity is especially conspicuous when the pretest probability of the least likely etiology is higher due to individual variability such as genetic predisposition or known malignant disease and/or when perturbations such as prior surgery or radiotherapy alter the normal anatomy and provoke an inflammatory tissue reaction.…”

Patient and Personnel Radiation Exposure in Sentinel Lymph Node Practice

“…Bağlanma etkinliğinin düşük olması ve F-18 FDG'nin kısa Operasyon sonrası kısa bir süre geçmiş olması nedeni ile de tanımlanan bulgular öncelikle operasyona sekonder benign enflamatuvar değişiklikleri düşündürmüştür. İstirahat sonrası fizik tedavi önerilen hastanın ağrıları hafiflemiş ve sol kalça mobilizasyonu sağlanmıştır yarı ömrü (110 dakika) nedeni ile sonuçta hastaya yeterli dozu enjekte edebilmek için, işaretleme yapılırken 2-3 kat fazla radyoaktivite ile başlanır (46). Teknik olarak enjeksiyondan 4-6 saat sonra görüntüleme yapılamaz.…”

“…Polimorf nükleer hücrelere %50'nin üzerinde bağlanması ve enfeksiyon alanında daha özgül tutulması nedeni ile çok düşük dozlarda uygulandığından HAMA oluşturmaz. Net olmamakla birlikte ciddi kardiyopulmoner yan etkileri raporlanan bu ürün piyasadan çekilmiştir (46). Mürin immünoglobulin G 1 antikor Fab' fragmanı Tc99m sulesomab (LeukoScan) granülositlerdeki NCA-90'a bağlanır.…”