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

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

Molecular Imaging of Fever of Unknown Origin:An Update

18F-FDG PET/CT, 67Ga-citrate and white blood cell (WBC) scintigraphy are molecular imaging techniques currently used in the diagnostic workup of fever of unknown origin. However, it is unknown which technique fits which patient group best. A systematic literature search has been performed for original articles regarding the use of molecular imaging in fever of unknown origin. A total of 820 eligible studies were screened of which 63 articles evaluating 5094 patients met the inclusion criteria. 18F-FDG PET/CT provided good diagnostic accuracy (with a weighted mean sensitivity, specificity, positive predicting value, negative predictive value, accuracy and helpfulness of 84.4%, 61.8%, 80.7%, 67.8%, 76.3%, and 61.1%, respectively). Even within specific patient groups such as children, elderly, patients with connective tissue diseases, patients on renal replacement therapy, and HIV-infected patients, 18F-FDG PET/CT provided good diagnostic values. For 67Ga-citrate scintigraphy, the weighted mean sensitivity, specificity, positive predictive value, negative predictive value, and helpfulness were 42.2%, 80.3%, 82.4%, 41.9%, and 42.2%, respectively. WBC scintigraphy shows a weighted mean sensitivity, specificity, positive predictive value, negative predictive value and accuracy of 73.5%, 86.3%, 79.1%, 82.4%, and 79.5%, respectively. However, compared to 67Ga-citrate and WBC scintigraphy, significantly more research has been performed using 18F-FDG PET/CT and 18F-FDG PET/CT has the advantage of relatively short procedural duration; it is therefore the preferred molecular diagnostic imaging technique. 67Ga-citrate and WBC scintigraphy can only be considered if 18F-FDG PET/CT is not available

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

Image Quality and Activity Optimization in Oncologic F-18-FDG PET Using the Digital Biograph Vision PET/CT System

The first Biograph Vision PET/CT system (Siemens Healthineers) was installed at the University Medical Center Groningen. Improved performance of this system could allow for a reduction in activity administration or scan duration. This study evaluated the effects of reduced scan duration in oncologic 18F-FDG PET imaging on quantitative and subjective imaging parameters and its influence on clinical image interpretation. Methods: Patients referred for a clinical PET/CT scan were enrolled in this study, received a weight-based 18F-FDG injected activity, and underwent list-mode PET acquisition at 180 s per bed position (s/bp). Acquired PET data were reconstructed using the vendor-recommended clinical reconstruction protocol (hereafter referred to as "clinical"), using the clinical protocol with additional 2-mm gaussian filtering (hereafter referred to as "clinical+G2"), and-in conformance with European Association of Nuclear Medicine Research Ltd. (EARL) specifications-using different scan durations per bed position (180, 120, 60, 30, and 10 s). Reconstructed images were quantitatively assessed for comparison of SUVs and noise. In addition, clinically reconstructed images were qualitatively evaluated by 3 nuclear medicine physicians. Results: In total, 30 oncologic patients (22 men, 8 women; age: 48-88 y [range], 67 ± 9.6 y [mean ± SD]) received a single weight-based (3 MBq/kg) 18F-FDG injected activity (weight: 45-123 kg [range], 81 ± 15 kg [mean ± SD]; activity: 135-380 MBq [range], 241 ± 47.3 MBq [mean ± SD]). Significant differences in lesion SUVmax were found between the 180-s/bp images and the 30- and 10-s/bp images reconstructed using the clinical protocols, whereas no differences were found in lesion SUVpeak EARL-compliant images did not show differences in lesion SUVmax or SUVpeak between scan durations. Quantitative parameters showed minimal deviation (∼5%) in the 60-s/bp images. Therefore, further subjective image quality assessment was conducted using the 60-s/bp images. Qualitative assessment revealed the influence of personal preference on physicians' willingness to adopt the 60-s/bp images in clinical practice. Although quantitative PET parameters differed minimally, an increase in noise was observed. Conclusion: With the Biograph Vision PET/CT system for oncologic 18F-FDG imaging, scan duration or activity administration could be reduced by a factor of 3 or more with the use of the clinical+G2 or the EARL-compliant reconstruction protocol