Hyperechoic amniotic membranes in patients with preterm premature rupture of membranes (p-PROM) and pregnancy outcome.

OBJECTIVES: The early identification of women with preterm premature rupture of membranes (p-PROM) who are at higher risk of imminent delivery remains challenging. The aim of our study was to evaluate if an increased echogenicity of the amniotic membranes may represent a sonographic marker of impending delivery in women with p-PROM. METHODS: This was a prospective study including women with singleton pregnancies and diagnosis of p-PROM between 22 and 37 gestational weeks. A sonographic examination was performed within 24 h from the hospital admission and the appearance of the amniotic membranes close to the internal os was specifically evaluated. The membranes were defined as hyperechoic when their echogenicity was similar to that of the fetal bones or normoechoic in the other cases. The primary aim of the study was to compare the admission to spontaneous onset of labor interval and the pregnancy outcome between the cases of p-PROM with and without hyperechoic membranes. RESULTS: Overall, 45 women fulfilled the inclusion criteria with similar characteristics at admission. In women with hyperechoic membranes, the admission to spontaneous onset of labor interval was significantly shorter (11.5 [5.3-25.0] vs. 3.0 [1.5-9.0] p=0.04) compared to women with normo-echoic membranes. At binomial logistic regression after adjustment for GA at hospital admission, the presence of hyperechoic membranes was found as the only independent predictor of spontaneous onset of labor ≤72 h (aOR: 6.1; 95% CI: 1.0-36.9). CONCLUSIONS: The presence of hyperechoic membranes is associated with a 6-fold higher incidence of spontaneous onset of labor within 72 h independently from the gestational age at p-PROM.

A new mobile self-dispensing and administering system for 18F-FDG: evaluation of operator dose reduction.

PURPOSE: Recently new mobile systems for dispensing positron emitters have been produced, designed to guarantee dispensing cycles in an aseptic environment. The aim of the present work was to assess the advantage of one of these systems in radiation protection of operators in clinical settings. METHODS: Recently, in our centre the new self-dispensing system named KARL100 by Tema Sinergie was adopted for 18F-FDG radiopharmaceuticals. The system is associated with an automatic Rad-inject infuser. The system that was previously used was a fixed isolator NMC DSI (Tema Sinergie), equipped with a µDDS-An activity fractioning system, together with a pneumatic post for the syringe delivery. The dosimetric evaluations on both systems were carried out through environmental measurements with an ionisation chamber and with the use of personal dosimeters. RESULTS: The operations of preparation and administration of 18F-FDG dose to the patient, with the use of Karl100 + RadInject, involve exposures much lower than those obtained by the fixed isolator. The average body exposure of the technician was reduced by 31%, and for the physician by 77%. On the extremities, the equivalent dose to the hands of the technician was reduced by 78%, and for the physician by 96%. Also the additional dosimeters worn by the technician confirmed the estimated environmental assessments. CONCLUSIONS: The exposures of the working personnel were significantly reduced with the introduction of the new KARL100 system.

Influence of PEG coating on the biodistribution and tumor accumulation of pH-sensitive liposomes.

Liposomes are lipid vesicles widely used as nanocarriers in targeted drug delivery systems for therapeutic and/or diagnostic purposes. A strategy to prolong the blood circulation time of the liposomes includes the addition of a hydrophilic polymer polyethylene glycol (PEG) moiety onto the surface of the vesicle. Several studies claim that liposome PEGylation by a single chain length or a combination of PEG with different chain lengths may alter the liposomes' pharmacokinetic properties. Therefore, the purpose of this study was to evaluate the influence of PEG on the biodistribution of pH-sensitive liposomes in a tumor-bearing animal model. Three liposomal formulations (PEGylated or not) were prepared and validated to have a similar mean diameter, monodisperse distribution, and neutral zeta potential. The pharmacokinetic properties of each liposome were evaluated in healthy animals, while the biodistribution and scintigraphic images were evaluated in tumor-bearing mice. High tumor-to-muscle ratios were not statistically different between the PEGylated and non-PEGylated liposomes. While PEGylation is a well-established strategy for increasing the blood circulation of nanostructures, in our study, the use of polymer coating did not result in a better in vivo profile. Further studies must be carried out to confirm the feasibility of the non-PEGylated pH-sensitive liposomes for tumor treatment.

Nuclear Medicine Therapy With 223Radium-dichloride for Osseous Metastases in Prostate Carcinoma.

Painful osseous metastasis resulting from castration-resistant prostate carcinoma is a common clinical problem. Historically, nuclear medicine offered several palliative beta-emitting radiopharmaceuticals targeting the skeleton with the goal of decreasing pain. However, these have largely been replaced by the alpha-emitting agent 223radium (Ra). 223Ra received Food and Drug Administration approval in 2013 for the treatment of metastatic castration-resistant prostate cancer with symptomatic bone metastases without visceral metastases. 223Ra offers an improved therapeutic profile due to its alpha-particle emissions resulting in a relatively higher linear energy transfer and lower particle range compared with beta-emitters. 223Ra also has demonstrated to increase overall survival in patients and to delay adverse skeletal events. Running a successful clinical nuclear therapy program with Ra requires a multidisciplinary team approach and this article suggests an implementation strategy from the authors' institution. Potential new nuclear radiopharmaceuticals still under investigation offering the future possibility of radioligand therapy are also discussed briefly.

How to harmonize SUVs obtained by hybrid PET/CT scanners with and without point spread function correction.

State of the art point-spread function (PSF) corrections implemented in positron emission tomography/computed tomography (PET/CT) reconstruction improved image quality and diagnostic performance but caused an increase in the standardized uptake value (SUV) compared to a conventional OSEM reconstruction system. The EANM suggested one produce two reconstructions, one optimised for maximum lesion detection and one for semi-quantitative analysis. In this work we investigated an alternative methodology, using a single reconstruction data set together with a post-reconstruction algorithm for SUV harmonization. Data acquisition was performed on a Siemens Biograph mCT system equipped with lutetium oxyorthosilicat crystals, PSF and time-of-flight algorithms and on a General Electric Discovery STE system equipped with BGO crystals. Both a EANM double reconstruction method and a dedicated post-reconstruction algorithm (marketed as EQ-filter) were tested to harmonize the quantitative values of the two PET/CT scanners. For phantom measurements we used a NEMA IQ phantom and a Jaszczak cylindrical phantom equipped with small spheres (lesion to background ratios of 8:1 and 4:1). Several different reconstruction settings were tested in order to provide a general methodology. Data obtained by phantom measurements were validated on seven oncologic patients who performed a one-bed extra acquisition on a different scanner. The evaluation regarded 39 small lesions (diameters: 0.3-2.6 cm) and was performed by two experienced nuclear medicine physicians. The SUV recoveries measured with the PSF reconstruction exceeded those obtained by the OSEM reconstruction with deviations ranging from 16% to 150%. These discrepancies resulted below 7% applying the optimized value of the EQ.filter or the double-reconstruction methods. For each reconstruction setting the optimal value of the EQ.filter was identified in order to minimize these discrepancies. Patient data, analyzed by Wilcoxon statistical test, confirmed and validated phantom measurements. EQ.filter can harmonize SUV values between different PET/CT scanners using a single reconstruction optimized to maximum lesion detectability. In this way, the second reconstruction proposed by EANM/EARL is avoided.

Correlation between umbilical vein-to-artery delta pH and type of intrapartum hypoxia in a cohort of acidemic neonates: A retrospective analysis of CTG findings.

INTRODUCTION: Umbilical artery blood analysis is assumed to give a picture of the acid-base balance of the infant at birth and is considered the gold standard to diagnose neonatal acidemia at birth. The evaluation of umbilical vein pH has been suggested as an adjunct in order to optimize the understanding of the pathophysiology of the hypoxic events in labor. The objective of this study was to assess the correlation between the Delta pH (vein-to-artery) on the umbilical cord and the intrapartum cardiotocography (CTG) patterns in a selected cohort of acidemic neonates. METHODS: Retrospective analysis of all CTG traces from non-anomalous term neonates consecutively born with acidemia (pH < 7.05 on the arterial cord) at four European tertiary Maternity Units. Intrapartum CTG traces were collected and their characteristics were reviewed in consensus by three senior Obstetricians. Each case was assigned to one of these four types of intrapartum hypoxia according to the CTG features: acute hypoxia, subacute hypoxia, slowly evolving hypoxia, and chronic hypoxia. The relationship between the different categories of intrapartum hypoxia and the Delta pH on the umbilical cord were evaluated. RESULTS: Overall, 83 acidemic neonates were included. Acute hypoxia, subacute hypoxia, slowly evolving hypoxia, and chronic hypoxia accounted for 19 (22.9%), 24 (28.9%), 24 (28.9%) and 16 (19.3%) cases, respectively. No difference of the Delta pH (p 0.61) was noted across the CTG subclasses, while significantly lower birthweight among cases with chronic hypoxia was found (p 0.03). The mean Delta pH did not vary at comparison between the cases with rapid onset hypoxia (acute + subacute hypoxia) and those with long lasting hypoxia (chronic + slowly evolving) (p 0.59). CONCLUSIONS: Within a selected cohort of acidemic neonates, our data do not demonstrate an association between the different CTG patterns of intrapartum hypoxia and the artery-to-vein Delta pH on the umbilical cord.

Sentinel lymph node biopsy in small papillary thyroid cancer. A review on novel surgical techniques.

PURPOSE: Sentinel lymph node biopsy (SNB) in patients with papillary thyroid carcinoma (PTC) and negative for clinically neck lymph node metastatic involvement (N0) has emerged as a promising minimally invasive procedure to detect metastatic nodes. METHODS: The MEDLINE database was searched via the PubMed interface on 10 January 2018 for the MeSH headings "sentinel lymph node biopsy" and "thyroid carcinoma". RESULTS: Vital blue dye, radioisotope, and the combination of both techniques are used in PTC patients. These methods and the emerging role of SPECT/CT are discussed in this review. The sentinel lymph node (SLN) identification rates ranged from 0 to 100% for blue dye, 83 to 100% for radioisotopes, and 66 to 100% for the combination of both techniques, respectively. CONCLUSIONS: SNB based on radioisotope technique with the use of intraoperative gamma-probe is an accurate and safe method that allows the highest SLN detection rate. There is sufficient evidence to propagate the increasing use of SNB procedure that has the potential to avoid prophylactic lymph node surgery in patients clinically N0.

FDG PET/CT in Aortic Valve Bioprosthesis Infection.

A 62-year-old man presented with persistent fever, weakness, and retrosternal pain 3 years after aortic valve bioprosthesis (AVR). His white blood cell count was 11,000/µL and C-reactive protein was 13.6 mg/dL. Consecutive blood cultures isolated Staphylococcus epidermidis and capitis. Transesophageal echocardiography demonstrated small aortic valve prosthesis vegetation. F-FDG PET/CT revealed prominent AVR activity, SUVmax = 12.2. He was treated with daptomycin, meropenem, and gentamicin for 1 month and followed by daptomycin and carbapenem for 3 months. Follow-up F-FDG PET/CT at 6 months demonstrated complete clearing of AVR activity associated with full asymptomatic recovery.

Catecholamine-Induced Chest Pain Mimicking Infarction Due to an MIBG-Negative and DOPA-Positive Succinate Dehydrogenase Syndrome Subunit B-Related Pheochromocytoma.

This 16-year-old boy presented with acute retrosternal pain possibly representing acute myocardial infarction. Cardiac enzymes were within reference ranges. There were marked increases in metanephrine to 3299 µg/24 h (reference, <400 µg/24 h), normetanephrine to 1309 µg/24 h (reference, 0-390 µg/24 h), and chromogranin A to 1605 ng/mL (reference, 0-150 µg/24 h). An incidental left adrenal mass was found during CTPA performed to exclude pulmonary embolism. I-MIBG scintigraphy was negative, and genetic screening detected SDHB (succinate dehydrogenase syndrome subunit B) gene mutation. Based on the gene mutation, F-DOPA PET/CT was performed, confirming a left-sided pheochromocytoma.

Technetium-99m radiolabeled paclitaxel as an imaging probe for breast cancer in vivo.

The high incidence and mortality of breast cancer supports efforts to develop innovative imaging probes to effectively diagnose, evaluate the extent of the tumor, and predict the efficacy of tumor treatments while concurrently and selectively delivering anticancer agents to the cancer tissue. In the present study we described the preparation of technetium-99m (99mTc)-labeled paclitaxel (PTX) and evaluated its feasibility as a radiotracer for breast tumors (4T1) in BALB/c mice. Thin Layer Chromatography (TLC) was used to determine the radiochemical purity and in vitro stability of 99mTc-PTX. PTX micelles showed a unimodal distribution with mean diameter of 13.46±0.06nm. High radiochemical purity (95.8±0.3%) and in vitro stability (over than 95%), up to 24h, were observed. Blood circulation time of 99mTc-PTX was determined in healthy BALB/c mice. 99mTc-PTX decays in a one-phase manner with a half-life of 464.3 minutes. Scintigraphic images and biodistribution were evaluated at 4, 8 and 24h after administration of 99mTc-PTX in 4T1 tumor-bearing mice. The data showed a significant uptake in the liver, spleen and kidneys, due to the importance of these routes for excretion. Moreover, high tumor uptake was achieved, indicated by high tumor-to-muscle ratios. These findings indicate the usefulness of 99mTc-PTX as a radiotracer to identify 4T1 tumor in animal models. In addition, 99mTc-PTX might be used to follow-up treatment protocols in research, being able to provide information about tumor progression after therapy.

Endocrine scintigraphy with hybrid SPECT/CT.

Nuclear medicine imaging of endocrine disorders takes advantage of unique cellular properties of endocrine organs and tissues that can be depicted by targeted radiopharmaceuticals. Detailed functional maps of biodistributions of radiopharmaceutical uptake can be displayed in three-dimensional tomographic formats, using single photon emission computed tomography (CT) that can now be directly combined with simultaneously acquired cross-sectional anatomic maps derived from CT. The integration of function depicted by scintigraphy and anatomy with CT has synergistically improved the efficacy of nuclear medicine imaging across a broad spectrum of clinical applications, which include some of the oldest imaging studies of endocrine dysfunction.

Is the detection rate of 18F-choline PET/CT influenced by androgen-deprivation therapy?

PURPOSE: To evaluate if the detection rate (DR) of (18)F-choline (18F-CH) PET/CT is influenced by androgen-deprivation therapy (ADT) in patients with prostate cancer (PC) already treated with radical intent and presenting biochemical relapse. MATERIALS AND METHODS: We have retrospectively evaluated (18)F-CH PET/CT scans of 325 consecutive PC patients enrolled in the period November 2009 to December 2012 previously treated with radical intent and referred to our centre to perform (18)F-CH PET/CT for biochemical relapse. Two different groups of patients were evaluated. group A included the whole sample of 325 patients (mean age 70 years, range: 49-86) who presented trigger PSA between 0.1 and 80 ng/ml (mean 5.5 ng/ml), and group B included 187 patients (mean age 70 years, range 49-86) with medium-low levels of trigger PSA ranging between 0.5 and 5 ng/ml (mean PSA 2.1 ng/ml); group B was chosen in order to obtain a more homogeneous group of patients in terms of PSA values also excluding both very low and very high PSA levels avoiding the "a priori" higher probability of negative or positive PET scan, respectively. At the time of examination, 139 patients from group A and 72 patients from group B were under ADT: these patients were considered to be hormone-resistant PC patients because from their oncologic history (>18 months) an increase of PSA levels emerged despite the ongoing ADT. The relationship between (18)F-CH PET/CT findings and possible clinical predictors was investigated using both univariate and multivariate binary logistic regression analyses, including trigger PSA and ADT. RESULTS: Considering the whole population, overall DR of (18)F-CH PET was 58.2 % (189/325 patients). In the whole sample of patients (group A), both at the univariate and multivariate logistic regression analysis, trigger PSA and ADT were significantly correlated with the DR of (18)F-CH PET (p < 0.05). Moreover, the DR in patients under ADT (mean PSA 7.8 ng/ml) was higher than in patients not under ADT (mean PSA 3.9 ng/ml), (DR was 70.5 % and 48.9 %, respectively; p < 0.001), therefore, demonstrating the existence of a significant correlation between the DR of (18)F-CH PET and ADT. In group B patients only trigger PSA resulted a reliable predictor of the (18)F-CH positivity, since ADT was not correlated to the DR of (18)F-CH PET (p = 0.061). Also in group B the DR of (18)F-CH PET in patients under ADT was higher than in patients not under ADT (65.3 % and 51.3 %, respectively) but the difference was not significant without a statistically significant correlation in the Mann Whitney test (p = 0.456) therefore, suggesting the lack of correlation between DR (18)F-CH PET/CT and ADT. CONCLUSION: Similarly to previous published studies, in our series the overall DR of (18)F-CH PET/CT was 58 % and was significantly correlated to trigger PSA. The most important finding of the present study is that ADT does not negatively influence DR of (18)F-CH PET/CT in PC patients with biochemical relapse; therefore, it can be suggested that it is not necessary to withdraw ADT before performing (18)F-CH PET/CT.

Biological target volume overlapping segmentation system method for avoiding false-positive PET findings in assessing response to neoadjuvant chemoradiation therapy in rectal cancer.

PURPOSE: FDG PET/CT has a recognized high predictive power to assess the response to neoadjuvant chemoradiation therapy (CRT) in patients affected by locally advanced rectal cancer (LARC), but a relatively high number of false-positive findings decrease its specificity: with the aim to solve this problem, a new method of imaging analysis is here proposed. METHODS: The new method here described, named Biological target volume (BTV) Overlapping Segmentation System (BOSS), has been applied on 24 consecutive patients with LARC that were all previously classified as nonresponders to CRT by means of the response index criterion that is adopted in our center. The BOSS method is based on the quantification of the amount of superimposition between pretreatment and posttreatment BTV. All BTVpre was down using a threshold of 60% of SUVmax in the tumor (BTV60). The results (overlap volumes and percentage of overlap volumes) were then matched up with postoperative pathology classified by the Mandard's tumor regression grade (TRG) system. RESULTS: Eleven patients were classified as responders (TRG1-2) and 13 as nonresponders (TRG 3-5). Among all the results obtained by BOSS method, only the percentage of overlap volume data between BTV60 and BTVpost (%Over_60) was able to correctly distinguish between responders and nonresponders. In our experience, a cutoff of 56% on the %Over_60 provided the best results in terms of true negative (11 cases), true positive (12 cases), false negative (1 case), and false positive (none). CONCLUSIONS: This new method, we developed, appears able to unmask the false-positive cases, improving the specificity of FDG PET/CT to predict the response to CRT patients with LARC.

18F-DOPA PET/CT in the evaluation of hereditary SDH-deficiency paraganglioma-pheochromocytoma syndromes.

PURPOSE: This study aims to evaluate the role of F-DOPA PET/CT in staging and follow-up of paraganglioma syndromes succinate dehydrogenase (SDH)-mutation-related patients, comparing F-DOPA PET/CT results with morphological imaging and biochemical results. PATIENTS AND METHODS: We retrospectively studied 10 consecutive patients (3 F, 7 M, mean age 32 yrs), all with a genetically demonstrated SDH mutation (5 SDH-D, 4 SDH-B, and 1 SDH-C) and all addressed to F-DOPA PET/CT scan. Seven patients had already been operated on for one or more pheochromocytomas and/or paragangliomas and were submitted to F-DOPA PET/CT scan according to clinical, biochemical, or radiological suspicion of recurrence, while 3 were only genetically positive, with no previous symptom/sign of the disease. For all patients, biochemical analysis (plasma and/or urinary catecholamine) and results of high-resolution morphological imaging studies (CT and/or MRI) were available. Histologic/cytologic findings or imaging and biochemical follow-up were taken as gold standard in all cases. RESULTS: Seven out of 10 patients showed one or more areas of pathological F-DOPA accumulation. PET/CT demonstrated the presence of the disease in 4/6 patients with no increase in catecholamine levels ("biochemically silent"). Positive detection rate was 100% in SDH-D and 40% in "non-SDHD". Analyzing per lesion, F-DOPA PET/CT demonstrated more lesions than anatomical imaging (16 vs. 7) especially in head and neck paragangliomas. CONCLUSIONS: F-DOPA PET/CT seems to be the more accurate method for staging and restaging patients with SDH-mutations-related paraganglioma syndromes. F-DOPA is particularly useful in detecting head and neck and biochemically silent paragangliomas, and also in apparently healthy mutation-carrying people.

Proposal of a new 18F-FDG PET/CT predictor of response in rectal cancer treated by neoadjuvant chemoradiation therapy and comparison with PERCIST criteria.

PURPOSE: The aim of this study was to correlate PERCIST criteria and a new criterion developed in our center that we named PREDIST (PET Residual Disease in Solid Tumor) with tumor regression grade (TRG) classification of pathologic response to neoadjuvant chemoradiotherapy (CRT) in patients affected by rectal cancer. METHODS: Seventy-three consecutive patients affected by locally advanced rectal cancer (LARC) were retrospectively included. FDG-PET/CT scans were performed at staging time and after the end of CRT (mean time 6.5 weeks). The analysis was performed by PERCIST criteria 1.0 and PREDIST criteria based on a new definition of residual disease. We split the TRG system into responders (TRG1-2) and nonresponders (TRG3-5). Pearson chi-square analysis by cross-tabulations was performed. RESULTS: PREDIST classification was statistically predictive of TRG response (P = 0.004, sensitivity 81.8% and specificity 54.9%). On the contrary, PERCIST criteria was not statistically correlated to TRG (P = 0.128) caused by a very low specificity (9.8%). CONCLUSIONS: FDG-PET/CT scan is an accurate tool to predict preoperatively the response to CRT in LARC patients. The novel proposed criterion (PREDIST) seems to be helpful to discriminate responder by nonresponder patients.

Proton magnetic resonance spectroscopy: ex vivo study to investigate its prognostic role in colorectal cancer.

BACKGROUND: Proton Magnetic Resonance Spectroscopy (1H MRS) is used for clinical diagnosis in some tumours. The aim of this study is to explore ex vivo the potential of 1H MRS in identifying malignancy through metabolic markers in the perspective of its application in all cases of difficult diagnosis and after neoadjuvant treatment. METHODS: Spectroscopy was performed ex vivo on 29 colorectal specimens. All patients were staged with imaging, underwent radical surgery and then followed-up. Spectral quantification analysis of components expressed in colorectal tumours and in healthy mucosa were evaluated. The MRS-tumour marker (MRS-tm) was calculated for each case. The U-test was used to compare MRS-tm in tumours and in healthy mucosa. In order to select a cut-off for MRS-tm in the tumour and healthy mucosa and to distinguish patients who were disease-free or with recurrence-progression, we performed the ROC curve analysis. RESULTS: In the 24 subjects without neoadjuvant treatment, it was found that MRS-tm is able to discriminate healthy and neoplastic tissue and can discriminate patients with risk of recurrence/progression CONCLUSION: Our data seem to show that 1H MRS may be successfully applied in vivo non-invasively to differentiate tumours from healthy mucosa and could also distinguish patients with different prognoses.

Parathyroid scintigraphy in renal hyperparathyroidism: the added diagnostic value of SPECT and SPECT/CT.

Secondary hyperparathyroidism (sHPT) is a major complication for patients with end-stage renal disease on long-term hemodialysis or peritoneal dialysis. When the disease is resistant to medical treatment, patients with severe sHPT are typically referred for parathyroidectomy (PTx), which usually improves biological parameters as well as clinical signs and symptoms. Unfortunately, early surgical failure with persistent disease may occur in 5%-10% of patients and recurrence reaches 20%-30% at 5 years. Presently, the use of parathyroid scintigraphy in sHPT is usually limited to the management of surgical failures after initial PTx. This review describes the strengths and limitations of typical (99m)Tc-sestamibi imaging protocols, and highlights the potential benefits of using parathyroid scintigraphy in the initial workup of surgical patients.

Cryptorchidism as a potential source of misinterpretation in ¹8FDG-PET imaging in restaging lymphoma patients.

PURPOSE: The estimated prevalence of cryptorchidism in young males is close to 2%. In oncological PET/CT studies, it might be difficult to recognize false-positive ¹8FDG uptake due to an ectopic testis. MATERIALS AND METHODS: In this pilot study, we report on three patients with lymphoma referred for assessment of response to treatment and in whom cryptorchidism was not known at the time of ¹8FDG-PET/CT imaging. RESULTS: In each of these patients, moderate ¹8FDG uptake corresponding to an ovoid mass in the inguinal canal was (or could has been) misinterpreted as a lymphoma-involved inguinal lymph node. Clues to avoid misinterpretation are discussed. CONCLUSION: Moderate ¹8FDG uptake in ectopic testes represents a potential source of false-positive at initial staging or evaluation of therapeutic response of lymphomas and other malignancies that needs to be recognized.

The role of 11C-choline PET imaging in the early detection of recurrence in surgically treated prostate cancer patients with very low PSA level <0.5 ng/mL.

PURPOSE: This study aims to evaluate the role of (11)C-choline PET/CT in patients with biochemical relapse after radical prostatectomy (RP) showing prostate-specific antigen (PSA) values lower than 0.5 ng/mL. METHODS: We performed (11)C-choline PET/CT in 71 consecutive patients previously treated with RP showing PSA values lower than 0.5 ng/mL. (11)C-Choline PET/CT was performed following standard procedure. (11)C-Choline PET/CT-positive findings were validated by transrectal ultrasonography + biopsy, repeated (11)C-choline PET/CT, other conventional imaging modality, and histology. RESULTS: (11)C-Choline PET/CT was true positive in 15/71 (21.1%). (11)C-Choline uptake was observed in pelvic lymph nodes (7/71; 9.9%), in the prostatic bed (7/71; 9.9%), and in bone (1/71; 1.4%). Mean PSA, PSA doubling time (PSAdt), and PSA velocity (PSAvel) values ± SD in (11)C-choline PET/CT-positive patients was 0.37 ± 0.1 ng/mL, 3.4 ± 2.1 months, and 0.05 ± 0.1 ng/mL/yr, respectively. (11)C-Choline PET/CT was false negative in 2 patients and false positive in 1 patient. Among all variables, only PSAdt and the ongoing hormonal treatment were statistically significant in the prediction of a positive (11)C-choline PET/CT at multivariate analysis. CONCLUSIONS: (11)C-Choline PET/CT could be used early after biochemical failure even if PSA values are very low, preferentially in hormonal resistant patients showing fast PSA kinetics. An early detection of the site of relapse could lead to a personalized and tailored treatment.

Role of ¹8F-choline PET/CT in suspicion of relapse following definitive radiotherapy for prostate cancer.

PURPOSE: The aims of the study were (a) to evaluate the diagnostic role, by means of positive detection rate (PDR), of ¹8F-choline (CH) positron emission tomography (PET)/CT in patients with prostate cancer treated with radiotherapy, with curative intent, and suspicion of relapse during follow-up, (b) to correlate the PDR with trigger prostate-specific antigen (PSA), (c) to investigate the possible influence of androgen deprivation therapy (ADT) at the time of scan on PDR and (d) to assess distribution of metastatic spread. METHODS: ¹8F-CH PET/CT exams from 46 consecutive patients (mean age 71.3 years, range 51-84 years) with prostate cancer (mean Gleason score 6.4, range 5-8) previously treated by definitive radiotherapy and with suspicion of relapse with negative or inconclusive conventional imaging were retrospectively evaluated. Of the 46 patients, 12 were treated with brachytherapy and 34 with external beam radiation therapy. Twenty-three patients were under ADT at the time of the examination. Trigger PSA was measured within 1 month before the exam (mean value 6.5 ng/ml, range 1.1-49.4 ng/ml). Patients were subdivided into four groups according to their PSA level: 1.0 < PSA ≤ 2.0 ng/ml (11 patients), 2.0 < PSA ≤ 4.0 ng/ml (16 patients), 4.0 < PSA ≤ 6.0 ng/ml (9 patients) and PSA > 6.0 ng/ml (10 patients). Correlation between ADT and PDR was investigated as well as between PSA and distribution of metastatic spread. RESULTS: The overall PDR of ¹8F-CH PET/CT was 80.4% (37/46 patients), increasing with the increase of trigger PSA. PDR of ¹8F-CH PET/CT is not influenced by ADT (p = 0.710) even if PET performed under ADT demonstrated an overall higher PDR (82.6%). The majority of the patients (59%, 22/37 patients) showed local relapse only, confined to the prostatic bed; 22% of the PET/CT-positive patients (8/37 patients) showed distant relapse only (bone localizations in all of them), while the remaining 19% (7/37 patients) showed both local and distant (lymph node and bone) spread. CONCLUSION: ¹8F-CH PET/CT showed a high overall detection rate (80%), proportional to the trigger PSA (both for local and distant relapse) not influenced by ADT. ¹8F-CH PET/CT is proposed as a first-line imaging procedure in restaging prostate cancer patients primarily treated with radiotherapy.