Carla Canevari

PVE Correction in PET-CT Whole-Body Oncological Studies From PVE-Affected Images

Partial Volume Effect (PVE) in PET-CT oncological studies affects the estimation of quantitative parameters useful for lesion malignancy differentiation and for monitoring disease and response to therapy. The aim of this work was to investigate the clinical feasibility and accuracy of PVE correction methods based on Recovery Coefficients (RC) as function of measured Lesion-to-Background ratio (L/B)m and measured lesion volume (Vm). PET-CT measurements were performed. The radioactivity concentration (Cm) and Vm were measured from images using Operator-Dependent and Operator-Independent (OI) techniques. RC curves were obtained combining RC from NEMA 2001 IQ phantom measurements as function of Sphere-to-Background ratio (S/B)m and sphere Vm. PVE correction was applied to PET-CT studies of anthropomorphic oncological phantoms and to PET-CT oncological studies (basal and follow up). The underestimation of Cm due to PVE in the NEMA IQ spheres (up to 80%) confirmed the severity of the error. The more feasible (always applicable, noise insensitive, reproducible) way to measure radioactivity was found by the use of an OI threshold technique. Our results showed that this measurement technique allows to achieve a PVE correction accuracy >; 87% (error in radioactivity estimate <; 13%) for a sphere diameter >; 1 cm. In patient studies the PVE correction was found to modify both SUV and SUV variations during patient follow up and our analysis showed that a PVE corrected SUV quantification increases the diagnostic confidence of oncological PET-CT studies.

Pre-transplant 18FDG-PET predicts outcome in lymphoma patients treated with high-dose sequential chemotherapy followed by autologous stem cell transplantation.

We evaluated the prognostic role of 18FDG-PET performed before ASCT in patients affected by lymphoma who underwent high-dose chemotherapy followed by ASCT as first-line treatment for high-risk disease or as second-line or more for relapsed or refractory disease. We retrospectively analyzed 53 consecutive patients, 14 with Hodgkin Lymphoma (HL) and 39 with non-Hodgkin Lymphoma (NHL), treated between February 1999 and October 2006 at our institution, who had a pre-ASCT FDG-PET (pPET) evaluation. Median age was 45 years (range: 18 – 69). After a median follow-up of 31 months (range: 8 – 91), 7 out of 16 pPET+ patients and 10 out of 37 pPET− patients experienced lymphoma relapse. The 5-year OS is 90% and 55% (p = 0.01) in patients with negative and positive pPET, respectively. In conclusion, a positive pPET indicates a poorer outcome after ASCT with respect to a negative pPET; this subset of patients should be considered candidate to more intensive or investigational approaches.

Nonpalpable breast lesions: preoperative radiological guidance in radioguided occult lesion localisation (ROLL)

PurposeThis study evaluated the methods, technical aspects and impact of preoperative radiological guidance in radioguided occult lesion localisation (ROLL) for single nonpalpable breast lesions.Materials and methodsA total of 288 patients underwent ROLL before surgery. Human serum albumin macroaggregates labelled with 3.7–7.4 MBq of technetium99 were injected into the lesion. In the case of ultrasonographic guidance (221/288 patients), inoculum positioning resulted in a change of echogenicity at the lesion site. In the case of mammographic guidance (67/288 patients), iodinated contrast medium was injected following the radiotracer for subsequent mammographic evaluation. Patients underwent surgery within 24 h from ROLL. A gamma-detecting probe was used to locate the lesion during surgery and guide its removal. After excision, the specimen was examined by either ultrasonography or mammography to verify complete lesion removal before histological evaluation.ResultsThe lesion was correctly localised in 281/288 patients (97.5%). One ROLL procedure failed because surgery could not be performed within 24 h and the radioactivity decayed. Of the six incorrect localisations, 2 were due to the radiological guidance and 4 to technetium99 dispersion.ConclusionsRadiological guidance in ROLL ensured the outcome of the procedure of localisation and removal of single, nonpalpable breast lesions in the majority of cases.RiassuntoObiettivoScopo del presente lavoro è stato quello di valutare metodi, aspetti tecnici ed impatto della guida radiologica preoperatoria nella radioguided occult lesion localisation (ROLL) per lesioni mammarie singole non palpabili.Materiali e metodiDuecentottantotto pazienti sono state sottoposte a ROLL prima dell’intervento. All’interno della lesione sono stati iniettati macro-aggregati di albumina umana marcata con tecnezio99; nel caso di guida ecografica (221/288 soggetti), l’inoculo ha prodotto iperecogenicità in corrispondenza della lesione; nel caso di guida mammografica (67/288 soggetti), dopo il radiotracciante è stato inoculato mezzo di contrasto iodato per il successivo controllo mammografico. Le pazienti sono state sottoposte ad intervento chirurgico entro 24 ore dalla ROLL. Per localizzare la lesione e guidarne la rimozione chirurgica, è stata utilizzata una sonda per la rilevazione dei raggi gamma. Dopo l’escissione, il pezzo operatorio è stato esaminato con ecografia o mammografia per verificare la completa rimozione della lesione.RisultatiLa lesione è stata localizzata correttamente in 281/288 pazienti (97,5%). Una ROLL non ha avuto successo poiché non è stato possibile effettuare l’intervento chirurgico entro 24 ore. Delle 6 localizzazioni non riuscite, 2 sono da mettere in relazione alla guida radiologica e 4 alla dispersione del tecnezio99.ConclusioniLa guida radiologica nella ROLL ha garantito l’esito della localizzazione e rimozione di lesioni mammarie singole non palpabili nella maggioranza dei casi.

Biomarkers from in vivo molecular imaging of breast cancer: pretreatment 18F-FDG PET predicts patient prognosis, and pretreatment DWI-MR predicts response to neoadjuvant chemotherapy

ObjectiveHuman cancers display intra-tumor phenotypic heterogeneity and recent research has focused on developing image processing methods extracting imaging descriptors to characterize this heterogeneity. This work assesses the role of pretreatment 18F-FDG PET and DWI-MR with respect to the prognosis and prediction of neoadjuvant chemotherapy (NAC) outcomes when image features are used to characterize primitive lesions from breast cancer (BC).Materials and methodsA retrospective protocol included 38 adult women with biopsy-proven BC. Patients underwent a pre-therapy 18F-FDG PET/CT whole-body study and a pre-therapy breast multi-parametric MR study. Patients were then referred for NAC treatment and then for surgical resection, with an evaluation of the therapy response. Segmentation methods were developed in order to identify functional volumes both on 18F-FDG PET images and ADC maps. Macroscopic and histogram features were extracted from the defined functional volumes.ResultsOur work demonstrates that macroscopic and histogram features from 18F-FDG PET are able to biologically characterize primitive BC, and define the prognosis. In addition, histogram features from ADC maps are able to predict the response to NAC.ConclusionOur work suggests that pre-treatment 18F-FDG PET and pre-treatment DWI-MR provide useful complementary information for biological characterization and NAC response prediction in BC.

Quantitative measurement of 18F-FDG PET/CT uptake reflects the expansion of circulating plasmablasts in IgG4-related disease

Objective [18F]Fluorodeoxyglucose (18F-FDG) PET/CT is increasingly used to assess organ involvement and response to treatment in IgG4-related disease (IgG4-RD), but clear correlations between 18F-FDG uptake and disease activity have not been established yet. We aimed to correlate the intensity and distribution of 18F-FDG uptake with validated clinical, serological and immunological parameters of IgG4-RD activity. Methods Twenty patients with active IgG4-RD underwent a baseline 18F-FDG PET/CT. Ten patients repeated 18F-FDG PET/CT after immunosuppressive treatments. 18F-FDG tissue uptake was measured using the standardized uptake value corrected for the partial volume effect (PVC-SUV) and the total lesion glycolysis (TLG) with (TLGtot+ln) and without (TLGtot-ln) lymph nodes. Disease activity was assessed by means of clinical parameters [IgG4-RD Responder Index (RI)], serological (ESR and CRP) and immunological (serum IgG4 and circulating plasmablasts) biomarkers. The enhanced liver fibrosis score was exploited as a biomarker for fibroblast activation. Results Thirteen (65%) patients had two or more organs affected by IgG4-RD. All patients had active IgG4-RD as defined by a median IgG4-RD RI value of 9 (range 6-15; normal < 3). Serum IgG4 and plasmablasts were elevated in 85% of patients. Circulating plasmablasts positively correlated with PVC-SUV (P = 0.027), inversely correlated with TLGtot-ln (P = 0.023) and did not correlate with TLGtot+ln (P > 0.05). No statistically significant correlation was found between PVC-SUV or TLG and IgG4-RD RI, ESR, CRP, serum IgG4 or enhanced liver fibrosis score (P > 0.05). Clinical response to immunosuppressive therapies was associated with a consensual reduction of circulating plasmablasts, PVC-SUV, TLGtot+ln and TLGtot-ln values (P < 0.05 for all comparisons). Conclusions 18F-FDG uptake of IgG4-RD lesions reflects immunological perturbations of the B cell compartment rather than fibroblast activation and extracellular matrix deposition. Conventional biomarkers of disease activity, namely IgG4-RD RI, ESR, CRP and serum IgG4 levels, do not appear to correlate with the radiometabolic activity of IgG4-RD lesions. In light of our results PET/CT represents a reliable instrument for assessing IgG4-RD activity, although lymph-node uptake deserves careful interpretation.

Prone 18F-FDG PET/CT changes diagnostic and surgical intervention in a breast cancer patient: some considerations about PET/CT imaging acquisition protocol

We report a case study demonstrating the value of prone positioning in positron emission tomography (PET) of a woman with diagnosed breast cancer (BC) addressed to lumpectomy. Surgeon required (18)F-fluorodeoxiglucose ((18)F-FDG) PET study for staging and assessment of lymphnode involvement/metastasis prior to lumpectomy: a whole-body supine study and a prone acquisition of breast. Supine study revealed one lesion, while prone study revealed two lesions. Prone PET findings changed diagnosis and therapeutic intervention for patient who was subsequently subjected to quadrantectomy.

Sentinel node mapping during laparoscopic distal gastrectomy for gastric cancer: technical notes

BackgroundWith increasing experience, sentinel node navigation has been applied even to gastric cancer. Sentinel lymph nodes are identified by injecting lymphatic tracer dye and radioisotope-labeled particles around a gastric tumor into the submucosa endoscopically. The aim of this video was to demonstrate the feasibility of laparoscopic sentinel node navigation (SLN) in gastric cancer.MethodsA 71-year-old man with a diagnosis of gastric cancer was admitted to the authors’ department. The preoperative workup demonstrated a uT1 node-negative gastric cancer. The patient was scheduled for laparoscopic distal gastrectomy with SLN. The day before surgery, the patient was submitted to endoscopy. During the procedure, the radiotracer (technetium-99) was injected at four points around the tumor. The operation was performed with the patient in the Lloyd-Davies position using four trocars. After opening of the gastrocolonic ligament, the patient underwent an intraoperative endoscopy, and blue dye (patent blue) was injected at four points around the tumor. The lymphatic basin was identified with the probe and the blue dye. The sentinel node then was identified. No pickup technique was used. A standard laparoscopic gastrectomy with intracorporeal anastomosis was concluded successfully. Through a supraumbilical incision, the specimen was extracted. The sentinel node was dissected at the bench table after the operation.ResultsThe pathologic report demonstrated a gastric carcinoma, namely, pT1, pN1 (Sentinel node (Sn), 1/36), G3 gastric cancer. Only the sentinel node was positive, containing a micrometastasis. The patient’s postoperative course was uneventful.ConclusionsSentinel node navigation with a double tracer during laparoscopic gastrectomy for cancer is feasible. Nevertheless, it is mandatory to standardize the method of SLN identification to increase the diagnosis of lymph node metastases.

An automatic segmentation method for the measurement of the functional volume of oncological lesions on MR ADC maps

Human cancers frequently display intra-tumor phenotypic heterogeneity, whose nature can have profound implications both for tumor development and therapeutic outcomes. Some recent research efforts have been devoted to develop advanced image processing methods able to extract imaging descriptors characterizing such intra-tumor phenotypic heterogeneity. However, most methods need to accurately define the lesion volume in order to extract imaging descriptors. This work aims at assessing a novel segmentation method to measure the functional volume of lesions on MR ADC maps. The method was validated in advanced breast cancer patients addressed to Neoadjuvant Chemotherapy and surgical intervention, undergoing pre-treatment FDG-PET and multi-parametric MR studies. PET metabolic volume (MTV), SUVmean, SUVmax, and Total Lesion Glycolysis (TLG) of lesions were measured using an already validated segmentation algorithm [Gallivanone et al., J. Instr. 2016]. The MR functional volume of lesions segmented on the ADC map resulted directly correlated to PET MTV. We defined a new parameter characterizing the MR total diffusion of lesions, the Total Lesion Diffusion (TLD) that resulted directly correlated to PET TLG. Furthermore, we assessed an inverse correlation between SUVmax and ADCmin within the PET and MR functional volumes, respectively. Textural indexes were also evaluated. Correlations (p<0.05) were found among the textural image descriptors related to the spatial distribution of the signal extracted within the PET and MR functional volumes. In conclusion, our segmentation method is effective to define the functional volume of lesions on ADC maps.

OP0035 Circulating Plasmablasts Levels Reflect Inflammatory Activity in IGG4-Related Disease Lesions as Assessed by Quantitative Positron Emission Tomography

Background IgG4-Related Disease (IgG4-RD) is a systemic inflammatory condition characterized by fibrous swelling of affected organs, serum IgG4 elevation, and IgG4+ plasmacells tissue infiltration. 18-Fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) scan is emerging as a promising imaging technique to detect organs involved by IgG4-RD and to assess disease response to treatment. The relationship between FGD-PET findings and immunological perturbations occurring in IgG4-RD has never been evaluated. Objectives To correlate the intensity and distribution of FDG-PET uptake with clinical and immunological parameters in patients with active untreated IgG4-RD. Methods Patients with active, untreated, biopsy proven IgG4-RD were included in the study. Disease activity was assessed through clinical (IgG4-RD Responder Index (RI)) and immunological (erythrocyte sedimentation rate (ESR), C reactive protein (CRP), serum IgG4, and circulating plasmablasts) parameters. Plasmablasts, a recently characterized disease biomarker, were identified as CD19+CD20-CD27+CD38bright cells on flow cytometry. FDG-PET/CT was performed in all patients at diagnosis. Quantitative assessment of FDG uptake was measured using the mean Standardized Uptake Value corrected for the Partial Volume Effect (PVC-SUV). Lymph nodes <1 cm of diameter were excluded from the analysis because of the risk of PVC-SUV over/under-estimation. In patients with multiorgan involvement, the IgG4-RD lesion with the highest PVC-SUV was selected to correlate FGD uptake with clinical and serological parameters. Results We studied 15 patients (7 males, 8 females) with a mean age of 63 years (range, 30–77 years). Twelve (80%) patients had multiorgan IgG4-RD involving lymphnodes (7 patients); aorta (5 patients); parotids glands and pancreas (3 cases each); bones, skin, thyroid, lung, submandibular and lachrymal glands (2 cases each); meninges, nasal cavity, oropharynx, palate, liver, CNS, and retrorbital space (one case each). The median IgG4-RD RI was 9 (range 6–16; normal =0). The median levels of ESR, CRP, serum IgG4 and plasmablasts at baseline were 30 mm/h (range 6–121 mm/h, normal <20 mm/h), 11.0 mg/L (range 0.0–48.0 mg/L; normal <6mg/L), 284.0 mg/dL (range 45–2100 mg/dL, normal <121 mg/dL), and 3870 cells/mL (range 1000–10000 cells/mL, normal <690 cells/mL), respectively. The median PCV-SUV was 6.24 (range 2.48–16.39). Significant positive correlation was found between PVC-SUV and serum plasmablasts levels (r=.84, p=.004). No correlation was found between PVC-SUV and either CRP, ESR, serum IgG4 levels, number of organs involved, and IgG4-RD RI at baseline (p>.05). Conclusions Our study demonstrates for the first time a positive correlation between circulating plasmablasts and inflammatory activity in IgG4-RD lesions as assessed by PVC-SUV on FDG-PET. Our results further strengthen the utility of circulating plasmablasts as a biomarker of disease activity. Conventional inflammatory markers, serum IgG4 levels, and IgG4-RD RI do not appear to correlate with metabolic activity in IgG4-RD lesions. References Ebbo M et al. Arthritis Care Res. 2014 Jan;66(1):86–96. Campochiaro C et al. Scand J Rheumatol. 2015 Sep 23:1–11. Disclosure of Interest None declared

Adaptive threshold method based on PET measured lesion-to-background ratio for the estimation of Metabolic Target Volume from 18 F-FDG PET images

Most advanced radiotherapy planning can be optimized by incorporating the metabolic image of the tumour to be irradiated (Metabolic Target Volume). MTV can be properly obtained by in vivo molecular imaging studies as the volume of metabolically active tumour component. Positron EmissionTomography (PET) can provide MTV by in vivo measuring the glucose metabolism of a tumour. Aim of this work was to develop an innovative PET image segmentation method, based on an adaptive threshold of the image signal-to-noise ratio, for the estimation of the MTV. The proposed method was tested on a set of anthropomorphic phantoms proving its feasibility, operator-independency and accuracy in a clinical setting.