Whole body MRI with Diffusion Weighted Imaging versus 18F-fluorodeoxyglucose-PET/CT in the staging of lymphomas.

PURPOSE: To assess the diagnostic performance of Whole Body (WB)-MRI in comparison with 18F-Fluorodeoxyglucose-PET/CT (18F-FDG-PET/CT) in lymphoma staging and to assess whether quantitative metabolic parameters from 18F-FDG-PET/CT and Apparent Diffusion Coefficient (ADC) values are related. MATERIALS AND METHODS: We prospectively enrolled patients with a histologically proven primary nodal lymphoma to  undergo 18F-FDG-PET/CT and WB-MRI, both performed within 15 days one from the other, either before starting treatment (baseline) or during treatment (interim). Positive and negative predictive values of WB-MRI for the identification of nodal and extra-nodal disease were measured. The agreement between WB-MRI and 18F-FDG-PET/CT for the identification of lesions and staging was assessed through Cohen's coefficient k and observed agreement. Quantitative parameters of nodal lesions derived from 18F-FDG-PET/CT and WB-MRI (ADC) were measured and the Pearson or Spearman correlation coefficient was used to assess the correlation between them. The specified level of significance was p ≤ 0.05. RESULTS: Among the 91 identified patients, 8 refused to participate and 22 met exclusion criteria, thus images from 61 patients (37 men, mean age 30.7 years) were evaluated. The agreement between 18F-FDG-PET/CT and WB-MRI for the identification of nodal and extra-nodal lesions was 0.95 (95% CI 0.92 to 0.98) and 1.00 (95% CI NA), respectively; for staging it was 1.00 (95% CI NA). A strong negative correlation was found between ADCmean and SUVmean of nodal lesions in patients evaluated at baseline (Spearman coefficient rs = - 0.61, p = 0.001). CONCLUSION: WB-MRI has a good diagnostic performance for staging of patients with lymphoma in comparison with 18F-FDG-PET/CT and is a promising technique for the quantitative assessment of disease burden in these patients.

Fibroblast Activation Protein Inhibitor (FAPI)-Based Theranostics-Where We Are at and Where We Are Heading: A Systematic Review.

Cancer is the leading cause of death around the globe, followed by heart disease and stroke, with the highest mortality to this day. We have reached great levels of understanding of how these various types of cancer operate at a cellular level and this has brought us to what we call "precision medicine" where every diagnostic examination and the therapeutic procedure is tailored to the patient. FAPI is among the new tracers that can be used to assess and treat many types of cancer. The aim of this review was to gather all the known literature on FAPI theranostics. A MEDLINE search was conducted on four web libraries, PUBMED, Cochrane, Scopus, and Web of Sciences. All of the available articles that included both diagnoses and therapy with FAPI tracers were collected and put through the CASP (Critical Appraisal Skills Programme) questionnaire for systematic reviewing. A total of 8 records were deemed suitable for CASP review, ranging from 2018 to November 2022. These studies were put through the CASP diagnostic checklist, in order to assess the goal of the study, diagnostic and reference tests, results, descriptions of the patient sample, and future applications. Sample sizes were heterogeneous, both for size as well as for tumor type. Only one author studied a single type of cancer with FAPI tracers. Progression of disease was the most common outcome, and no relevant collateral effects were noted. Although FAPI theranostics is still in its infancy and lacks solid grounds to be brought into clinical practice, it does not show any collateral effects that prohibit administration to patients, thus far, and has good tolerability profiles.

The prognostic power of inflammatory indices and clinical factors in metastatic castration-resistant prostate cancer patients treated with radium-223 (BIO-Ra study).

PURPOSE: To combine peripheral blood indices and clinical factors in a prognostic score for metastatic castration-resistant prostate cancer (mCRPC) patients treated with radium-223 dichloride ([223Ra]RaCl2). PATIENTS AND METHODS: Baseline neutrophil-to-lymphocyte ratio (NLR), derived NLR (donor), lymphocyte-to-monocyte ratio (LMR), platelet-to-lymphocyte ratio (PLR), systemic inflammation index (SII), Eastern Cooperative Oncology Group performance status (ECOG PS), Gleason score (GS) group, number of bone metastases, prostate-specific antigen (PSA), alkaline phosphatase (ALP), line of therapy, previous chemotherapy, and the presence of lymphadenopathies were collected from seven Italian centers between 2013 and 2020. Lab and clinical data were assessed in correlation with the overall survival (OS). Inflammatory indices were then included separately in the multivariable analyses with the prognostic clinical factors. The model with the highest discriminative ability (c-index) was chosen to develop the BIO-Ra score. RESULTS: Five hundred and nineteen mCRPC patients (median OS: 19.9 months) were enrolled. Higher NLR, dNLR, PLR, and SII and lower LMR predicted worse OS (all with a p < 0.001). The multivariable model including NLR, ECOG PS, number of bone metastases, ALP, and PSA (c-index: 0.724) was chosen to develop the BIO-Ra score. Using the Schneeweiss scoring system, the BIO-Ra score identified three prognostic groups (36%, 27.3%, and 36.6% patients, respectively) with distinct median OS (31, 26.6, and 9.6 months, respectively; hazard ratio: 1.62, p = 0.008 for group 2 vs. 1 and 5.77, p < 0.001 for group 3 vs. 1). CONCLUSIONS: The BIO-Ra score represents an easy and widely applicable tool for the prognostic stratification of mCRPC patients treated with [223Ra]RaCl2 with no additional costs.

The prognostic value of 123I-mIBG SPECT cardiac imaging in heart failure patients: a systematic review.

This systematic review aimed to evaluate the prognostic value of Iodine123 Metaiodobenzylguanidine (123I-mIBG) SPECT myocardial imaging in patients with heart failure (HF) and to assess whether semi-quantitative SPECT scores can be useful for accurate risk stratification concerning arrhythmic event (AE) and sudden cardiac death (SCD) in this cohort. A systematic literature search of studies published until November 2020 regarding the application of 123I-mIBG SPECT in HF patients was performed, in Pubmed, Scopus, Medline, Central (Cochrane Library) and Web Of Science databases, including the words "MIBG", "metaiodobenzylguanidine", "heart", "spect", and "tomographic". The included studies had to correlate 123I-mIBG SPECT scores with endpoints such as overall survival and prevention of AE and SCD in HF patients. According to the sixteen studies included, the analysis showed that 123I-mIBG SPECT scores, such as summed defect score (SDS), regional wash-out (rWO), and regional myocardial tracer uptake, could have a reliable prognostic value in patients with HF. An increased SDS or rWO, as well as a reduced 123I-mIBG myocardial uptake, have proven to be effective in predicting AE- and SCD-specific risk in HF patients. Despite achieved results being promising, a more reproducible standardized method for semi-quantitative analysis and further studies with larger cohort are needed for 123I-mIBG SPECT myocardial imaging to be as reliable and, thus, accepted as the conventional 123I-mIBG planar myocardial imaging.

A National Multicenter Study on overall survival in elderly metastatic castrate-resistant prostate cancer patients treated with Radium-223.

BACKGROUND: Radium-223 prolongs overall survival (OS) and delays time to the first symptomatic skeletal events in patients with symptomatic metastatic castration-resistant prostate cancer (mCRPC). There is a lack of evidence on the safety and efficacy of Radium-223 treatment in the very elderly population. AIMS: Aim of this multicentre study is to analyze mCRPC patients treated with Radium-223 in terms of OS and to assess whether there are differences between young and elderly, as well as to verify efficacy and safety in patients ≥ 75 years of age. METHODS: 430 mCRPC patients of six Italian Centres were analyzed in this multicenter retrospective study. At baseline and after each cycle were collected clinical and diagnostic patients' parameters. The whole cohort was divided into two groups based on the age of the patients (< 75 years old and ≥ 75 years old). RESULTS: 47% of the patients were < 75 years old and 53% were ≥ 75 years old. The primary outcome, OS, does not show significant differences between the two subgroups if other basal parameters are considered. Considering clinical covariates in univariate models (p < 0.05) several clinical aspects have an impact on OS, except for age (p = 0.072). Age continues to have no significant impact on the OS (p = 0.274) even in multivariate models in the two groups. The toxic effects are similar in the two groups. CONCLUSIONS: Radium-223 prolongs survival in both younger and older patients at the same baseline condition and is a good option in the symptomatic mCRPC setting compared to other agents.

Prognostic and Theranostic Applications of Positron Emission Tomography for a Personalized Approach to Metastatic Castration-Resistant Prostate Cancer.

Metastatic castration-resistant prostate cancer (mCRPC) represents a condition of progressive disease in spite of androgen deprivation therapy (ADT), with a broad spectrum of manifestations ranging from no symptoms to severe debilitation due to bone or visceral metastatization. The management of mCRPC has been profoundly modified by introducing novel therapeutic tools such as antiandrogen drugs (i.e., abiraterone acetate and enzalutamide), immunotherapy through sipuleucel-T, and targeted alpha therapy (TAT). This variety of approaches calls for unmet need of biomarkers suitable for patients' pre-treatment selection and prognostic stratification. In this scenario, imaging with positron emission computed tomography (PET/CT) presents great and still unexplored potential to detect specific molecular and metabolic signatures, some of whom, such as the prostate specific membrane antigen (PSMA), can also be exploited as therapeutic targets, thus combining diagnosis and therapy in the so-called "theranostic" approach. In this review, we performed a web-based and desktop literature research to investigate the prognostic and theranostic potential of several PET imaging probes, such as 18F-FDG, 18F-choline and 68Ga-PSMA-11, also covering the emerging tracers still in a pre-clinical phase (e.g., PARP-inhibitors' analogs and the radioligands binding to gastrin releasing peptide receptors/GRPR), highlighting their potential for defining personalized care pathways in mCRPC.

Fracture risk and survival outcomes in metastatic castration-resistant prostate cancer patients sequentially treated with abiraterone acetate and RADIUM-223.

PURPOSE: To evaluate the fracture risk and survival outcomes in patients with metastatic castration-resistant prostate cancer (mCRPC) who received sequentially abiraterone acetate (AA) and radium 223 [223Ra]RaCl2 in the daily clinical practice. MATERIALS: We retrospectively reviewed the records of mCRPC patients who received [223Ra]RaCl2 immediately after progressing during an AA treatment line in everyday clinical practice. RESULTS: We reviewed data of a consecutive series of 94 mCRPC patients. Most of the patients (85.1%) received [223Ra]RaCl2 as second- or third-line treatment. [223Ra]RaCl2 treatment was well-tolerated; there were only four cases of grade 3 anaemia, two cases of grade 3 leukopenia and one case of grade 3 neutropenia. The overall fracture rate is 2.1%; one fracture was recorded during the course of [223Ra]RaCl2 treatment, and one was recorded 1 month after its end. The fractures both occurred at metastatic sites. Median OS from [223Ra]RaCl2 start was more than 14 months regardless of the treatment line when [223Ra]RaCl2 was administered. CONCLUSION: The findings of this study show that the treatment with [223Ra]RaCl2 immediately after AA was active and safe with a very low risk of a fracture. Thus, the present observational report makes a valuable contribution to the current debate concerning the risks and benefits of including [223Ra]RaCl2 in the therapeutic algorithm.

Baseline quality of life predicts overall survival in patients with mCRPC treated with 223Ra-dichloride.

OBJECTIVE: The prognostic value of baseline clinical parameters in predicting the survival prolonging effect of radium-223-dichloride (223Ra)-therapy in metastatic castration resistant prostate cancer (mCRPC) patients is still an open issue. The aim of this study was investigating the impact of baseline quality of life (QoL) on overall survival (OS) in mCRPC patients treated with 223Ra. The present study also evaluated the trend of patient-reported QoL during both 223Ra-treatment and post-therapy follow-up period. MATERIALS AND METHODS: One hundred and seventy-three consecutive mCRPC patients treated with 223Ra were included in this prospective study. Quality of life was assessed through EORTC QLQ-C30 and QLQ-BM22 questionnaires and 2264 questionnaires were evaluated. Other baseline variables relevant to the OS analysis have been considered. Data were summarized using descriptive statistics, univariate and multivariate analysis with Cox model. A principal component analysis (PCA) on the questionnaires' results compiled at baseline was performed to reduce the data to a one-dimensional score. Joint models for survival and longitudinal data were finally used in order to evaluate the relationship between the time-depended QoL scores and OS. RESULTS: On multivariate analysis, baseline patients' hemoglobin (Hb), total alkaline phosphatase (tALP), and two EORTC QLQ-C30 items, physical functioning (HR=0.970,CI=0.960-0.980, P<0.001) and dyspnea (HR=0.992,CI=0.986-0.999, P=0.023), were significantly associated with OS. In the resulting model of the multivariate analysis performed after PCA, baseline patients' Hb, tALP and QoL-score were independent significant predictors of OS (QoL-score: HR=0.995-95%CI=0.992 - 0.998, P=0.001). The OS analysis stratified by score of baseline QoL, showed a median OS of 8 (95%CI=6-11) and 16 (95%CI=12-24) months for scores respectively below and above the cut-off value (log-rank-P<0.001). The joint model showed a significant deterioration of QoL-score during both 223Ra-therapy and follow-up period (P<0.001). CONCLUSION: Baseline QoL is a significant predictor of OS, meaning that patients with better pretreatment QoL are more likely to obtain a marked survival prolonging effect from 223Ra.

Role of cardiac 123I-mIBG imaging in predicting arrhythmic events in stable chronic heart failure patients with an ICD.

BACKGROUND: Despite therapeutic improvement, the prognosis of chronic heart failure (CHF) remains unfavorable partly due to arrhythmia and sudden cardiac death (SCD). This prospective study evaluated myocardial 123I-meta-iodobenzylguanidine (123I-mIBG) scintigraphy as a predictor of arrhythmic events (AE) in CHF patients. METHODS: 170 CHF patients referred for implantable cardioverter-defibrillator (ICD) implantation for both primary and secondary prevention were enrolled. All patients underwent planar and SPECT imaging. Early and late heart-to-mediastinum (H/M) ratio, 123I-mIBG washout (WO), early and late summed SPECT scores were calculated The primary endpoint was an AE: sustained ventricular tachycardia, resuscitated cardiac arrest, appropriate ICD therapy or SCD. The secondary endpoint was appropriate ICD therapy. RESULTS: During a median follow-up of 23.3 months, 69 patients experienced an AE. Early summed score (ESS) was the only independent predictor of AE [HR 1.023 (1.003-1.043)]. Focussing on only patients with an ICD for primary prevention, ESS was the only independent predictor of AE [HR 1.028 (1.007-1.050)]. 123I-mIBG-derived parameters failed to be independent predictors of appropriate ICD therapy. However there was a "bell-shaped" relation between 123I-mIBG scintigraphy-derived parameters and AE and appropriate ICD therapy, i.e., those with intermediate 123I-mIBG abnormalities tended to be at higher risk of events. CONCLUSION: Although SPECT 123I-mIBG scintigraphy was associated with AE in CHF patients with ICD implantation for primary and secondary prevention, no association was found between 123I-mIBG scintigraphy-derived parameters and appropriate ICD therapy.

No evidence of association between psychological distress and pain relief in patients with bone metastases from castration-resistant prostate cancer treated with 223Radium.

OBJECTIVE: Painful bone metastases cause reduced quality of life (QoL) in patients with castration-resistant prostate cancer (CRPC). Alpha-emitter 223Radium is associated with a clear survival benefit and significant bone pain palliation in CRPC patients with symptomatic bone metastases. The aim of this study was to evaluate the association between pain relief and psychological distress during the time course of therapy in patients treated with 223Radium. METHODS: A total of 63 patients with mCRPC undergoing 223Radium treatment in our Nuclear Medicine Unit, carefully instructed on the possibility of improving the pain and increasing the survival by the treatment, were retrospectively evaluated. Pain response during treatment was assessed with the Brief Pain Inventory Numeric Rating Scale. Psychological distress was evaluated through the analysis of specific items from EORTC QoL questionnaires C30 and BM22, submitted to patients at baseline and after each 223Radium cycle. RESULTS: Pain intensity showed a significant decrease after first 223Radium administration (-1.03 points, p = 0.0032), with a subsequent stability through the course of treatment (-1.30 points, p = <0.001). Psychological status did not show significant variations during 223Radium treatment, and no association was found between psychological status and pain relief in our population. CONCLUSIONS: In our experience, bone pain palliation provided by 223Radium do not correlate with an improved psychological status in patients with advanced PC. This observation emphasises the role of the psychological aspect in the evaluation of the QoL and the necessity of a multidisciplinary approach in which the emotional aspect of the patient is carefully evaluated.

Narrative medicine in metastatic prostate cancer reveals ways to improve patient awareness & quality of care.

AIM: To describe the journey of patients with metastatic castration-resistant prostate cancer (mCRPC) in treatment with radium-223. METHODS: A multiperspective analysis was performed using narrative medicine in four Italian centers. RESULTS: The substantial impact of mCRPC on quality of life through all phases of the disease was described. After an initial lack of awareness of the disease or denial of its effects, symptoms of pain, fatigue and side effects often led to sadness, fear and loneliness. The majority underwent radium-223 therapy positively, restoring their quality of life and routine activities. CONCLUSION: Using narrative medicine, the importance of a patient-centered approach in the pathway of care for patients with mCRPC through all the stages of the disease was highlighted.

Practical recommendations for radium-223 treatment of metastatic castration-resistant prostate cancer.

PURPOSE: Radium Ra 223 dichloride (radium-223, Xofigo®) is the first targeted alpha therapy for patients with castration-resistant prostate cancer and symptomatic bone metastases. Radium-223 provides a new treatment option for this setting, but also necessitates a new treatment management approach. We provide straightforward and practical recommendations for European nuclear medicine centres to optimize radium-223 service provision. METHODS: An independent research consultancy agency observed radium-223 procedures and conducted interviews with all key staff members involved in radium-223 treatment delivery in 11 nuclear medicine centres across six countries (Germany, Italy, the Netherlands, Spain, Switzerland and the UK) experienced in administering radium-223. The findings were collated and discussed at a meeting of experts from these centres, during which key consensus recommendations were defined. RESULTS: The recommendations cover centre organization and preparation; patient referral; radium-223 ordering, preparation and disposal; radium-223 treatment delivery/administration; and patient experience. Guidance includes structured coordination and communication within centres and multidisciplinary teams, focusing on sharing best practice to provide high-quality, patient-centred care throughout the treatment pathway. CONCLUSIONS: These expert recommendations are intended to complement existing management guidelines. Sharing best practice and experience will help nuclear medicine centres to optimize radium-223 service provision and improve patient care.

Dosimetry of bone metastases in targeted radionuclide therapy with alpha-emitting (223)Ra-dichloride.

PURPOSE: Ra-dichloride is an alpha-emitting radiopharmaceutical used in the treatment of bone metastases from castration-resistant prostate cancer. Image-based dosimetric studies remain challenging because the emitted photons are few. The aim of this study was to implement a methodology for in-vivo quantitative planar imaging, and to assess the absorbed dose to lesions using the MIRD approach. METHODS: The study included nine Caucasian patients with 24 lesions (6 humeral head lesions, 4 iliac wing lesions, 2 scapular lesions, 5 trochanter lesions, 3 vertebral lesions, 3 glenoid lesions, 1 coxofemoral lesion). The treatment consisted of six injections (one every 4 weeks) of 50 kBq per kg body weight. Gamma-camera calibrations for (223)Ra included measurements of sensitivity and transmission curves. Patients were statically imaged for 30 min, using an MEGP collimator, double-peak acquisition, and filtering to improve the image quality. Lesions were delineated on (99m)Tc-MDP whole-body images, and the ROIs superimposed on the (223)Ra images after image coregistration. The activity was quantified with background, attenuation, and scatter correction. Absorbed doses were assessed deriving the S values from the S factors for soft-tissue spheres of OLINDA/EXM, evaluating the lesion volumes by delineation on the CT images. RESULTS: In 12 lesions with a wash-in phase the biokinetics were assumed to be biexponential, and to be monoexponential in the remainder. The optimal timing for serial acquisitions was between 1 and 5 h, between 18 and 24 h, between 48 and 60 h, and between 7 and 15 days. The error in cumulated activity neglecting the wash-in phase was between 2 % and 12 %. The mean effective half-life (T 1/2eff) of (223)Ra was 8.2 days (range 5.5-11.4 days). The absorbed dose (D) after the first injection was 0.7 Gy (range 0.2-1.9 Gy. Considering the relative biological effectiveness (RBE) of alpha particles (RBE = 5), D RBE = 899 mGy/MBq (range 340-2,450 mGy/MBq). The percent uptake of (99m)Tc and (223)Ra (activity extrapolated to t = 0) were significantly correlated. CONCLUSION: The feasibility of in vivo quantitative imaging in (223)Ra therapy was confirmed. The lesion uptake of (223)Ra-dichloride was significantly correlated with that of (99m)Tc-MDP. The D RBE to lesions per unit administered activity was much higher than that of other bone-seeking radiopharmaceuticals, but considering a standard administration of 21 MBq (six injections of 50 kBq/kg to a 70-kg patient), the mean cumulative value of D RBE was about 19 Gy, and was therefore in the range of those of other radiopharmaceuticals. The macrodosimetry of bone metastases in treatments with (223)Ra-dichloride is feasible, but more work is needed to demonstrate its helpfulness in predicting clinical outcomes.

Positron emission computed tomography targeting urokinase plasminogen activator receptor (uPAR) in cancer: a systematic review.

INTRODUCTION: To provide an overview of the available literature data on clinical applications of positron emission tomography (PET) targeting the urokinase-type plasminogen activator receptor in oncology. METHODS: A literature search was conducted in PubMed, Web of Science and Scopus databases up to June 2023. The results were presented according to the PRISMA guidelines. The quality of the studies was assessed using the Critical Appraisal Skill Program checklist. RESULTS: Seven papers were selected for final analysis, involving 266 patients with solid tumors who underwent PET with uPAR-ligands. Thematic areas identified include feasibility studies (n = 2) on the safety, pharmacokinetics, and dosimetry of uPAR-targeting radiopharmaceuticals; uPAR-directed imaging in head and neck cancer (n = 2); uPAR PET in prostate cancer (n = 2); and the investigation of uPAR in neuroendocrine neoplasms (n = 1). Six of the seven studies used the radiopharmaceutical [68Ga]Ga-NOTA-AE105 while one study used [64Cu]Cu-DOTA-AE105. The studies showed protocol homogeneity, with static PET imaging at 20 minutes. The quality assessment revealed limitations such as small cohorts and the fact that all studies were performed by a single research group. CONCLUSIONS: uPAR-PET appears to be a promising imaging tool in well-selected oncological settings, but it needs to be validated by multicentre collaboration.

Extraosseous distribution of 99mTc-diphosphonates during bone scintigraphy: review of the literature with case series presentation.

PURPOSE: Technetium-99m (99mTc)-diphosphonates represent the most common radiopharmaceutical used for bone scintigraphy. Even if the uptake in bone tissue has been widely explored, atypical uptake could be seen in soft tissue malignancies during bone scintigraphy. Increased vascularization and endothelium permeability represent front-row players in the biodistribution of the tracer, albeit other causes have been identified such as trauma, necrosis, the presence of calcification in metastasis, the pH of the tissue and consequently the type of ion concentration. CONCLUSION: The aim of this paper is to summarize the state of art of atypical soft tissue uptake seen in cancer tissues. The research was conducted on PubMed. The analysis of the literature suggests that calcium metabolism and ionic saturation have a pivotal role in the biodistribution of bone tracers. This phenomenon ranks in a complex scenario that includes carcinogenesis and cancer environment aspects. We also report two cases in our Institution in which atypical uptake in cancer tissues was observed.

Functional Imaging in Musculoskeletal Disorders in Menopause.

Menopause-related musculoskeletal (MSK) disorders include osteoporosis, osteoarthritis (OA), sarcopenia and sarco-obesity. This review focuses on the applications of nuclear medicine for the functional imaging of the aforementioned clinical conditions. Bone Scan (BS) with 99mTc-labeled phosphonates, alone or in combination with MRI, can identify "fresh" vertebral collapse due to age-associated osteoporosis and provides quantitative parameters characterized by a good correlation with radiological indices in patients with OA. 18F-NaF PET, particularly when performed by dynamic scan, has given encouraging results for measuring bone turnover in osteoporosis and allows the evaluation of subchondral bone metabolic activity in OA. FDG PET can help discriminate between pathological and nonpathological vertebral fractures, especially by applying appropriate SUV-based thresholds. In OA, it can effectively image inflamed joints and support appropriate clinical management. Preliminary evidences suggest a possible application of FDG in sarco-obesity for the detection and quantification of visceral adipose tissue (VAT). Further studies are needed to better define the role of nuclear medicine in menopause-related MSK disease, especially as regards the possible impact of new radiopharmaceuticals (ie, FAPI and RGD peptides) and recent technological advances (eg, total-body PET/CT scanners).

The new bone WB-SPECT/CT: hybrid, from head-to-toe and digital! Is it worth the effort?

INTRODUCTION: A bone scan (BS) plays a pivotal role in many oncological and non-oncological conditions. The planar BS is characterized by high sensitivity but low specificity. With respect to planar imaging, the implementation of single-photon emission computed tomography (SPECT) has allowed increased image contrast and more accurate tracer localization. AREAS COVERED: Recent technological innovations in the field of BS are treated, with a particular focus on multi-field-of-view devices allowing to cover the entire scan length with a 3D acquisition (WB-SPECT/CT). In addition, the applications of cadmium zinc telluride/CzT detectors capable of converting gamma photons directly into electrical impulses (i.e. 'digital SPECT') are discussed. EXPERT OPINION: Initial clinical experiences indicate that WB-SPECT/CT is characterized by higher sensitivity, diagnostic accuracy, and increased confidence in image interpretation with respect to the 'old-fashioned' BS (planar images with or without a single field-of-view SPECT). Furthermore, CzT-based detectors, thanks to their superior sensitivity, might be helpful to implement fast acquisition protocols. Further studies are needed to better define the clinical impact of bone CzT WB-SPECT/CT on patients' management and outcome, as well as its cost-benefit ratio.