Expert opinions in nuclear medicine: Finding the “holy grail” in infection imaging

Nuclear medicine imaging techniques are now widely accepted and increasingly used for diagnosing and treatment monitoring of infectious and inflammatory diseases. The latter has been exemplified by numerous recent clinical guidelines in which PET imaging is now part of the diagnostic flowcharts. In this perspective paper we discuss the current available guidelines, the current limitations, and we provide the future aims of research to achieve the holy grail in nuclear medicine: the differentiation between infection, inflammation and malignancy

Diagnostic errors in clinical FDG-PET/CT

Purpose: To determine the frequency, types, and determinants of diagnostic errors in clinical FDG-PET/CT, based on addenda to the original report. Materials and Methods: This retrospective study included 4,099 consecutive clinical FDG-PET/CT scans with corresponding reports that were made at a tertiary care center in an 18-month period. FDG-PET/CT reports were scrutinized for the presence of an addendum enclosing a diagnostic error. Results: 90 of 4,099 FDG-PET/CT reports (2.2%) contained an addendum enclosing a diagnostic error. The distribution of perceptual and cognitive errors among these 90 diagnostic errors was 54 (60.0%)/36 (40.0%). On multivariate logistic regression analysis, only low-dose FDG-PET/CT combined with concomitantly acquired and interpreted full-dose contrast-enhanced CT remained as significantly and independently associated with the presence of a diagnostic error, relative to low-dose FDG-PET/CT without concomitantly acquired and interpreted full-dose contrast-enhanced CT (odds ratio: 2.79 [95% confidence interval: 1.61-4.851, P <0.001). Patient age, gender, hospital status, indication for FDG-PET/CT scanning, single vs. double reading (i.e. two medical imaging specialists), reader experience, and reading by a nuclear medicine physician only vs. reading by both a nuclear medicine physician and a radiologist, were not significantly and independently associated with the presence of a diagnostic error. Conclusion: Diagnostic errors in clinical FDG-PET/CT based on addenda to the original report are relatively infrequent, though certainly non-negligible. Perceptual errors are slightly more frequent than cognitive errors. The availability of a concomitantly acquired and interpreted full-dose contrast-enhanced CT seems to increase diagnostic error rate. These data can be used for quality improvement and benchmarking purposes

Radionuclide Imaging of Fungal Infections and Correlation with the Host Defense Response

The human response to invading fungi includes a series of events that detect, kill, or clear the fungi. If the metabolic host response is unable to eliminate the fungi, an infection ensues. Some of the host response's metabolic events to fungi can be imaged with molecules labelled with radionuclides. Several important clinical applications have been found with radiolabelled biomolecules of inflammation. 18F-fluorodeoxyglucose is the tracer that has been most widely investigated in the host defence of fungi. This tracer has added value in the early detection of infection, in staging and visualising dissemination of infection, and in monitoring antifungal treatment. Radiolabelled antimicrobial peptides showed promising results, but large prospective studies in fungal infection are lacking. Other tracers have also been used in imaging events of the host response, such as the migration of white blood cells at sites of infection, nutritional immunity in iron metabolism, and radiolabelled monoclonal antibodies. Many tracers are still at the preclinical stage. Some tracers require further studies before translation into clinical use. The application of therapeutic radionuclides offers a very promising clinical application of these tracers in managing drug-resistant fungi

Imaging cardiac innervation in amyloidosis

Cardiac amyloidosis is a form of restrictive cardiomyopathy resulting in heart failure and potential risk on arrhythmia, due to amyloid infiltration of the nerve conduction system and the myocardial tissue. The prognosis in this progressive disease is poor, probably due the development of cardiac arrhythmias. Early detection of cardiac sympathetic innervation disturbances has become of major clinical interest, because its occurrence and severity limits the choice of treatment. The use of iodine-123 labelled metaiodobenzylguanidine ([I-123]MIBG), a chemical modified analogue of norepinephrine, is well established in patients with heart failure and plays an important role in evaluation of sympathetic innervation in cardiac amyloidosis. [I-123]MIBG is stored in vesicles in the sympathetic nerve terminals and is not catabolized like norepinephrine. Decreased heart-to-mediastinum ratios on late planar images and increased wash-out rates indicate cardiac sympathetic denervation and are associated with poor prognosis. Single photon emission computed tomography provides additional information and has advantages for evaluating abnormalities in regional distribution in the myocardium. [I-123]MIBG is mainly useful in patients with hereditary and wild-type ATTR cardiac amyloidosis, not in AA and AL amyloidosis. The potential role of positron emission tomography for cardiac sympathetic innervation in amyloidosis has not yet been identified

The value of prebiopsy FDG-PET/CT in discriminating malignant from benign vertebral bone lesions in a predominantly oncologic population

Purpose: To determine the value of prebiopsy 18F-fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET)/computed tomography (CT) in discriminating malignant from benign vertebral bone lesions. Materials and methods: This retrospective study included 53 patients with 55 vertebral bone lesions that underwent FDG-PET/CT before CT-guided biopsy. Pathologic examination of the biopsy sample and a minimum follow-up of 1 year were used as reference standard. Results: Sensitivity, specificity, positive predictive value, and negative predictive value of visual FDG-PET analysis (with lesion FDG uptake higher than liver FDG uptake as threshold for malignancy) in discriminating malignant from benign vertebral bone lesions were 91.3% (42/46), 22.2% (2/9), 85.7% (42/49), and 33.3% (2/6), respectively. The semiquantitative FDG-PET metrics SUVmax and SUVpeak achieved areas under the receiver operating characteristics curve of 0.630 and 0.671, respectively. Malignant lesions demonstrated bone lysis more frequently than benign lesions (60.9% (28/46) vs. 22.2% (2/9)), and this difference was nearly significant (P = 0.064). All other clinical and conventional imaging characteristics (including patient age, gender, previous diagnosis of malignancy, bone pain, weight loss, any CT abnormality, sclerosis, cortical destruction, bone marrow replacement, associated extraosseous soft tissue mass, and accompanying vertebral height loss, multiple bone lesions on FDG-PET/CT, and suspicious extraosseous lesions on FDG-PET/CT) were not significantly different (P = 0.143 to 1.000). Conclusion: FDG-PET/CT may steer the diagnosis (particularly thanks to a relatively high PPV and value of semiquantitative measurements), but cannot always classify vertebral bone lesions as malignant or benign with sufficient certainty. In these cases, biopsy and/or follow-up remain necessary to establish a final diagnosis

Can FDG-PET/CT replace blind bone marrow biopsy of the posterior iliac crest in Ewing sarcoma?

OBJECTIVE: To determine and compare the value of (18)F-fluoro-2-deoxy-D-glucose positron emission tomography/computed tomography (FDG-PET/CT) to blind bone marrow biopsy (BMB) of the posterior iliac crest in detecting metastatic bone marrow involvement in newly diagnosed Ewing sarcoma. MATERIALS AND METHODS: This retrospective study included 20 patients with newly diagnosed Ewing sarcoma who underwent pretreatment FDG-PET/CT and a total of 38 blind BMBs (two unilateral and 18 bilateral) of the posterior iliac crest. FDG-PET/CT scans were evaluated for bone marrow involvement, both in the posterior iliac crest and other sites, and compared to blind BMB results. RESULTS: FDG-PET/CT was positive for bone marrow involvement in 7/38 posterior iliac crests, whereas BMB was positive in 5/38 posterior iliac crests. FDG-PET/CT and BMB results in the posterior iliac crest agreed in 36/38 cases (94.7%, 95% confidence interval [CI]: 82.7-98.5%). On a patient level, FDG-PET/CT was positive for bone marrow involvement in 4/20 patients, whereas BMB of the posterior iliac crest was positive in 3/20 patients. On a patient level, FDG-PET/CT and BMB results agreed in 19/20 patients (95.0%, 95% CI: 76.4-99.1%). The only discrepancies between FDG-PET/CT and BMB were observed in two BMBs of one patient. Both BMBs in this patient were negative, whereas FDG-PET/CT indicated bilateral posterior iliac crest involvement and also extensive bone marrow involvement elsewhere. CONCLUSIONS: FDG-PET/CT appears to be a valuable method for metastatic bone marrow assessment in newly diagnosed Ewing sarcoma. The routine use of blind BMB of the posterior iliac crest should be reconsidered when FDG-PET/CT is available

Letter to the Editor regarding Falstie-Jensen et al:"Labeled white blood cell/bone marrow single-photon emission computed tomography with computed tomography fails in diagnosing chronic periprosthetic shoulder joint infection''

No abstract availabl