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Coronavirus disease (COVID-19) outbreak has profoundly changed the organization of hospital activities. We present our experience of reorganization of a nuclear medicine service settled in Northern Italy during the pandemic period of March and April 2020 characterized a government-mandated lockdown. Our service remained open during the whole period, performing approximately 80% of the routine practice, while maintaining it COVID-free despite the geographical context characterized by a high risk of infection. Reorganization involved all aspects of a nuclear medicine department, following local, national, and international guidelines for prioritizing patients, telephone and physical triages, deployment of appropriate personal protective equipment, social distancing, and logistic changes for scheduling examinations and disinfection procedures. All staff remained COVID-19-negative despite the unintentional admission of 4 patients who later turned out to be positive for the severe acute respiratory syndrome coronavirus 2. These adopted measures would serve as the basis for safe nuclear medicine services in the post-lockdown phase.

In this paper, a new methodological approach to using PET information in radiotherapy treatment planning has been discussed. Computed tomography (CT) represents the primary modality to plan personalized radiation treatment, because it provides the basic electron density map for correct dose calculation. If PET scanning is also performed it is typically coregistered with the CT study. This operation can be executed automatically by a hybrid PET/CT scanner or, if the PET and CT imaging sets have been acquired through different equipment, by a dedicated module of the radiotherapy treatment planning system. Both approaches have some disadvantages: in the first case, the bore of a PET/CT system generally used in clinical practice often does not allow the use of certain bulky devices for patient immobilization in radiotherapy, whereas in the second case the result could be affected by limitations in window/level visualization of two different image modalities, and the displayed PET volumes can appear not to be related to the actual uptake into the patient. To overcome these problems, at our centre a specific procedure has been studied and tested in 30 patients, allowing good results of precision in the target contouring to be obtained. The process consists of segmentation of the biological target volume by a dedicated PET/CT console and its export to a dedicated radiotherapy system, where an image registration between the CT images acquired by the PET/CT scanner and a large-bore CT is performed. The planning target volume is contoured only on the large-bore CT and is used for virtual simulation, to individuate permanent skin markers on the patient.

Lung cancer (LC) still represents one of the most common tumours in both women and men. PET/CT is a whole-body non-invasive imaging procedure that has been increasingly used for the assessment of LC patients. In particular, PET/CT added value to CT is mainly related to a more accurate staging of nodal and metastatic sites and to the evaluation of the response to therapy. Although the most common PET tracer for LC evaluation is 18F-FDG, new tracers have been proposed for the evaluation of lung neuroendocrine tumours (68Ga-DOTA-peptides, 18F-DOPA) and for the assessment of central nervous system metastasis (11C-methionine). This review focuses on the main clinical applications and accuracy of PET/CT for the detection of non-small cells lung cancer (NSCLC), broncho-alveolar carcinoma (BAC), small cells lung cancer (SCLC), lung neuroendocrine tumours (NET) and solitary pulmonary nodules (SPN).

The most common malignancy affecting the liver is metastasis from a wide variety of tumors, particularly those of gastrointestinal origin. Successful surgical removal of a solitary liver metastasis may significantly extend survival and optimal preoperative assessment in this regard is a mandatory prerequisite for proper patient selection. The addition of positron emission tomography/computed tomography (PET/CT) to other more conventional imaging procedures (e.g., ultrasound (US), CT, and magnetic resonance) has the potential to greatly improve the selection process by the combination of high-resolution anatomy afforded by CT directly combined with the functional scintigraphic map of intra- and extrahepatic lesions depicted by 2-deoxy-2-[F-18]fluoro-D-glucose (FDG)-PET. In this study, we assess the additional value of PET/CT in the management strategy of patients with solitary liver metastasis from colorectal and other cancers identified by conventional imaging methods.We evaluated 43 consecutive patients (17 males, 26 females, mean age 53 +/- 6 years) with known solitary liver metastasis. This sample consisted of 18 patients with colorectal cancer, 15 with nonsmall cell lung cancer, six with breast carcinoma, and four ovarian cancers. In addition to contrast-enhanced CT and US, all patients were studied with FDG-PET/CT before surgery. PET/CT was performed within 3 weeks of the initial diagnosis and the scans were read by two experienced radiologists/nuclear medicine specialists blinded to the clinical data. A final diagnosis was obtained at surgery in 31 patients, by fine needle biopsy in five, and long-term clinical, biochemical, and follow-up imaging in seven patients.In 12 out of 43 patients (28%), PET/CT resulted in restaging disease and a change in therapy. Twenty-two of 31 patients with confirmed solitary liver lesions (71%) were disease-free, eight of 31 (26%) developed a new recurrence, and one of 31 (3%) died from disease progression over a 17 +/- 6-month follow-up interval. Nine of 12 patients (75%) with multiple metastases demonstrated by FDG-PET/CT were alive with disease and three of 12 (25%) deceased due to disease progression (p0.01) over a 17 +/- 6-month follow-up interval.The addition of FDG-PET/CT to the routine assessment of patients with liver metastasis has a significant impact on disease staging and selection of suitable candidates for solitary liver metastasis resection and outcome.

AIM To evaluate clinical efficacy of a dual-time acquisition protocol, which included 4 and 20/24-h imaging with antigranulocyte antibody scintigraphy (LeukoScan) combined with semiquantitative analysis in the diagnosis of infection in painful hip prosthesis. METHODS Sixty-seven consecutive patients with hip prosthesis were enrolled in this research project: 35 females, 32 males, mean age of 56.3 years. All patients had clinical and biochemical suspicious of infection. Each prosthesis had been implanted 3 months to 12 years before enrollment in this study. Twenty-four patients were on antibiotic therapy at the time of scintigraphy. Seven patients had bilateral hip prosthesis, one painful and the other painless: the seven painless prostheses were considered controls. LeukoScan examination was performed both at early (4 h) and delayed (20/24 h) times. The scintigraphic data were assessed both by visual and semiquantitative methods by three experienced nuclear medicine physicians blinded to clinical, laboratory and radiographic results. The uptake was graded visually by a 4-point scale: intense=3, moderate=2, mild=1 and absent=0. The semiquantitative analysis was obtained by a region of interest (ROI) analysis used in the anterior views to measure the ratio between the mean radioactivity in the prosthesis and the background radioactivity in the early and delayed images. An increase in the intensity of uptake of at least one scale-step at visual analysis and 20% at semiquantitative ROI analysis at the dual-time (early vs. delayed) LeukoScan was considered consistent with infection, whereas a stable or decreasing pattern was judged a negative result. Three-phase 99mTc-hydroxymethane diphosphonate bone scan was also performed routinely. Final diagnosis was determined at surgery and/or long-term clinical and imaging follow-up. RESULTS At visual analysis, sensitivity for both early and delayed imaging was 94%, whereas specificity was 71% for early imaging and 83% for early and delayed imaging approach. At semiquantitative ROI analysis, sensitivity remained 94%, whereas specificity rose slightly to 73% for early imaging and to 90% for early and delayed imaging combined. Of note, four false-positive early scans were diagnosed correctly as negative on delayed imaging showing a decreasing pattern in uptake intensity. Sensitivity and specificity were similar whether patients were on or off antibiotic therapy. CONCLUSION Our data show that early imaging LeukoScan is highly sensitive in evaluating septic prosthesis, but it is not optimally specific. Although the dual-time LeukoScan is capable of significantly increasing specificity for detecting infection. The semiquantitative ROI analysis further increased the specificity. Concomitant antibiotic treatment did not seem to influence the diagnostic efficacy of LeukoScan scintigraphy in detecting infected hip prosthesis.

OBJECTIVE To evaluate clinical efficacy of a dual-time acquisition protocol consisting of early 4 h and delayed 20-24 h imaging with anti-granulocyte scintigraphy (LeukoScan) in the diagnosis of infection in painful total knee arthroplasty (TKA). MATERIALS AND METHODS Seventy-eight consecutive patients with TKA (12 bilateral) were prospectively enrolled in the study from August 2004 to July 2005. All the patients had clinical and biochemical suspicious of infection, except for the 12 patients with bilateral painless prosthesis who had no signs and symptoms of loosening and/or infection and were considered as controls. TKA prostheses had been implanted 4 months to 9.5 years before our studies. Forty-three patients were on antibiotic therapy at the moment of scintigraphic examination, and treatment was not discontinued. All patients underwent LeukoScan examination by performing both early 4 h and delayed 20-24 h imaging. In addition to planar imaging SPECT was performed in 18 cases. A decrease in radiotracer uptake from early to delayed LeukoScan imaging was interpreted as an unspecific finding (negative for infection), while an increasing uptake was interpreted as a positive finding for the presence of infection. Three-phase Tc-MDP bone scan was also routinely performed by standard technique. Sensitivity and specificity of early and delayed LeukoScan imaging were calculated. RESULTS Sensitivity for early and delayed imaging were 92.7%, while specificity was 78.4% for early imaging and 100% for delayed imaging approach. SPECT imaging did not add any significant information as regard to specificity in our experience. Eight false positive early scans were correctly diagnosed as negative at delayed imaging. Three false negative results were recorded. Sensitivity and specificity were similar when patients were on or off antibiotic therapy. Imaging was negative in all 12 controls. CONCLUSIONS Our results, based on a large group of patients, suggest that delayed LeukoScan imaging is important in identifying false positive results detect at early imaging. Thus, a dual-time, 4 h early and 20-24 h delayed LeukoScan imaging approach should be recommended to increase the diagnostic accuracy of the scintigraphy, with the exception of patients with a negative early LeukoScan examination, in whom the acquisition of delayed imaging appears unnecessary. In our experience, concomitant antibiotic therapy did not influence the diagnostic value of LeukoScan.

This study, which was based on a large series of consecutive patients imaged by 111In-pentetreotide SPECT for a neuroendocrine tumor, evaluated variability in reconstruction parameters in relation to patient body weight and the body region imaged, looking for the possibility of standardizing such parameters. Methods: One hundred twenty-four patients underwent 111In-pentetreotide scintigraphy: 4- and 24-h whole-body and planar scans and a 24-h SPECT examination. All patients were injected with 140–150 MBq of 111In-pentetreotide at least 1 wk after somatostatin analogs had been discontinued. SPECT images were systematically acquired at the levels of the head, chest, and abdomen. SPECT was performed using a dual-head γ-camera with medium-energy collimators, step-and-shoot method, no circular orbit, a 64 × 64 matrix, and 30 s per view for a total of 64 views. Two reconstruction procedures were compared: the iterative method using 10 iterations and the filtered backprojection method using a Butterworth filter with different cutoffs and orders. Results: Optimal SPECT images were obtained by applying the Butterworth filter. The reconstruction parameters could be standardized for the head and chest but were more variable for the abdomen, mainly because 111In-pentetreotide is physiologically trapped in different intestinal areas and varies over time, especially in the liver, spleen, bowel, and urinary tract. Conclusion: Filtered backprojection using a Butterworth filter appears adequate for standardizing the reconstruction parameters for 111In-pentetreotide SPECT of the head and chest. Processing of abdominal images is more operator-dependent. A 150-MBq dose of 111In-pentetreotide is recommended when planning multiple SPECT acquisitions in the same patient.

A 67-year-old man, previously operated for a pancreatic neuroendocrine tumor (NET), had progressive increase of serum chromogranin A during follow-up. Sequential 68Ga-DOTA-NOC and F-18 FDG PET/CT were performed. 68Ga-DOTA-NOC imaging was negative, whereas F-18 FDG PET/CT showed 2 hypermetabolic hepatic lesions demonstrated at CT-guided biopsy as metastatic deposits from a high-grade (G3) aggressive NET. Despite the large consensus of SPECT or PET with radiolabeled somatostatin analogs as first choice in functional imaging for detecting NETs metastasis, F-18 FDG may occasionally be the right tracer to provide accurate diagnostic and prognostic information in aggressive G3 NET.

The aim of this study was to evaluate the efficacy of ¹⁸F-choline PET/CT (18FCH-PET/CT) in restaging patients previously treated by radical prostatectomy for a prostate cancer, presenting with biochemical relapse during follow-up (FU).Three hundred thirty-one patients referred to us from January 2009 to April 2011 to perform 18FCH PET/CT were evaluated: 233 of them (mean age 69.7 years) met the inclusion criteria of the study: (1) biochemical relapse after radical prostatectomy (trigger PSA0.2 ng/mL) (n=224) and (2) high risk for relapse (elevated Gleason score≥8) in spite PSA0.1 ng/mL during FU (n=9). Trigger PSA was available for all patients (mean 8 ng/mL) and in 44 of them also PSA kinetic (PSA velocity-PSAvel; PSA doubling time-PSAdt). Correlation between 18FCH PET/CT detection rate and trigger PSA, PSAvel, PSAdt, and tumoral spread distribution were evaluated by univariate and multivariate analysis. Subsequent minimum FU was 1 year (mean 26 months, range 12-40).Overall detection rate of 18FCH PET/CT was 54%, which significantly increased when the trigger PSA increases (P0.001). PET-positive patients presented a "fast" PSA kinetic (mean PSAdt=6 months and mean PSAvel=9.3 ng/mL/yr), while PET-negative patients presented a "slow" PSA kinetic (mean PSAdt=15.4 months and mean PSAvel=0.9 ng/mL/yr). Disease relapse was local in 17% of cases, distant in 66%, and combined in 17%.Overall 18FCH PET/CT detection rate was 54% (ie, similar to that reported in literature with ¹¹C-choline), which increases with the increase in trigger PSA: this condition was particularly true in patients with accelerated PSA kinetic. In about 20% of patients, 18FCH PET/CT demonstrated local relapses early enough to offer locoregional radiation therapy.

Purpose Every PET scanner suffers of the partial volume effect (PVE), that is a loss of contrast in small lesions causing a worsening in standardized uptake value (SUV) accuracy, that is critical if quantitative PET/CT imaging is used for diagnosis and therapy. Methods In order to quantify PVE and optimize our clinical protocols to minimize this effect in a last generation PET/CT scanner, we utilized a cylindrical phantom equipped with ten mini- and micro-volume hollow spheres. The lesion detectability and the SUV accuracy were evaluated at a fixed spheres to background intrinsic contrast (activity concentration ratio 8:1) but in different scan conditions: (a) acquisition modality (3D vs. 2D), (b) number of subset per iteration, (c) type of post-reconstruction filter and (d) activity concentration (i.e. total counts). Also the effect of different absorber thickness was evaluated. Results Small lesion detectability resulted better in images acquired in 3D mode rather than 2D, mainly because of the lower noise produced by the fully-3D algorithm. The number of reconstruction iterations and the post-processing filter used affected both the contrast underestimation and the spatial resolution. Decreasing the 18F activity injected according to the low-dose protocol, the small lesions could be distinguished from the background down to a diameter of 6.2 mm and the SUV accuracy did not deteriorate. Adding absorber thickness around the phantom, the image noise slightly increased while SUV accuracy did not change. Conclusions The hybrid PET/CT scanner we evaluated showed good performances, mainly in 3D acquisition modality. The phantom measurements showed that the most appropriate reconstruction protocol derived from a compromise between the contrast accuracy and the noise variance in PET images. The low-dose protocol clinically used demonstrated no loss in SUV accuracy and an adequate lesion detectability for lesions down to 6.2 mm in diameter.

This is a case of a 48-year-old man treated with surgery and (131)I for papillary thyroid carcinoma: a follow-up (18)F-FDG PET/CT incidentally evidenced pituitary uptake, also seen in (111)In-octreoscan as increased uptake in the sellar area. MRI confirmed a pituitary mass. The patient did not show any signs or symptoms related to this lesion; 1 year later, both PET/CT and MRI findings remained unchanged. Surgery confirmed nonfunctioning benign pituitary adenoma. This single case observed in 12,873 consecutive patients scanned in our center confirms the possibility that nonfunctioning benign pituitary adenomas may be FDG-avid: uptake mechanisms remain unknown, and targeted studies are needed.

L-6-fluoro 3,4-dihydroxyphenylalanine (18F-DOPA), an amino acid-based radiopharmaceutical, is increasingly being used in the detection and management of neuroendocrine tumours. Knowledge of the normal biodistribution of this radiopharmaceutical is essential for the proper interpretation of such studies, but the literature available is scanty due to the rarity of these tumours. The aim of this study is to evaluate the biodistribution pattern and normal variants of 18F-DOPA in a cohort of patients with neuroendocrine tumours using semiquantitative analysis (maximum standardized uptake value).We analysed 107 consecutive 18F-DOPA PET/CT studies of patients referred with medullary carcinoma of the thyroid (43), phaeochromocytoma including cases of Von Hippel Lindau syndrome and multiple endocrine neoplasia type IIA cases (34), paraganglioma (14) and other neuroendocrine tumours (16). The study population were divided into two groups: those with negative 18F-DOPA PET/CT scans (32) and those with positive scans (75). The biodistribution of 18F-DOPA in each group was measured and compared between the two groups.The physiological biodistribution in the basal ganglia and liver parenchyma showed no variability between the two groups. Conversely, uptake in the pancreas (particularly the uncinate process) and adrenals showed considerable variability between the groups. However, these differences were found not to be significant on statistical analysis.The data presented may provide useful information in understanding the physiologic biodistribution of DOPA and its variants, for the purpose of improving the interpretation of 18F-DOPA PET/CT.

of F-FDG-PET/CT Gaia Grassetto, Carlo Capirci, Maria Cristina Marzola, Lucia Rampin, Sotirios Chondrogiannis, Alessandra Musto, Giorgio Crepaldi, Anna Maria Minicozzi, Arianna Massaro, Domenico Rubello Department of Nuclear Medicine—PET/CT Centre, Santa Maria della Misericordia Hospital, Via Tre Martiri 89, 45100 Rovigo, Italy Radiotherapy Unit, Santa Maria della Misericordia Hospital, Rovigo, Italy Oncology Unit, Santa Maria della Misericordia Hospital, Rovigo, Italy Clinical Surgery, University of Verona, Verona, Italy

Dear Sir, We read with interest the recent paper by Rubello et al. entitled “Role of Tc-sestamibi SPECT in accurate selection of primary hyperparathyroid patients for minimally invasive radio-guided surgery” [1]. Minimally invasive radio-guided surgery (MIRS) is widely employed for primary hyperparathyroidism caused by a solitary parathyroid adenoma. Since an intraoperative gamma probe is used, significant sestamibi uptake by the adenoma is important [2, 3]. Obviously, as the authors underline, radiation attenuation problems may cause underestimation of the sestamibi uptake by adenomas in an anterior planar image, resulting in doubt as to the appropriateness of MIRS in some cases. In this regard the authors report an interesting finding, namely that the parathyroid to background (P/B) ratio derived from SPECT correlates well with the intrasurgery P/B ratio; this means that using SPECT it is possible to predict the intraoperative measurement obtained with the gamma probe, thus allowing better patient selection for MIRS. However, we believe that this finding is not going to have a significant impact on the selection of patients for MIRS since only patients with a high probability of having a solitary adenoma are candidates for MIRS [4]. In our experience most of these patients demonstrate a P/B ratio significantly higher than the threshold, referred to by the authors, of 1.2 in the anterior planar image and thus do not require any quantitative confirmation. In the case of deeply located adenomas, despite the relatively reduced sestamibi intensity in the anterior planar image, they will still be well recognised as parathyroid lesions and any doubt about the appropriateness for MIRS in those cases can be dispelled just by knowing that the adenoma is located deeply. In this regard we visually estimate the depth and at the same time take into account the attenuation effect on sestamibi uptake from adenomas by using oblique planar imaging in all cases, rather than the time-consuming and rather complicated SPECT technique. Oblique planar imaging is easy to perform and very valuable even when the adenoma is behind the thyroid gland [5, 6]. In the presented study the ratio derived from SPECT was useful in only 1/22 patients although 7/22 adenomas were deeply located. The quantification might possibly be useful in estimating the appropriateness of the sestamibi uptake for MIRS in a few borderline cases. However, trying to include these patients will inevitably increase the probability of multiple gland disease since it is well known that frequently only the largest gland is visible in hyperplasia, especially in the early stages, when the size of the other glands remains below the sensitivity of the techniques used [7, 8]. The result will then be that more operations will be changed to bilateral exploration assuming that rapid PTH measurement is available. In this regard, SPECT, because of its slightly better sensitivity compared with planar imaging, would be most useful not in selecting more patients but rather in excluding some on the basis of the identification of more than one parathyroid lesion in cases of multi-gland disease. Nevertheless, ultrasound can contribute this important information even better than SPECT. In conclusion, we believe that in the selection of eligible patients for MIRS, quantification is not needed and that performance of SPECT exclusively for this purpose is not justified. Eur J Nucl Med Mol Imaging (2007) 34:607–608 DOI 10.1007/s00259-006-0332-y