Fit of biokinetic data in molecular radiotherapy: a machine learning approach

BACKGROUND

In literature are reported different analytical methods (AM) to choose the proper fit model and to fit data of the time-activity curve (TAC). On the other hand, Machine Learning algorithms (ML) are increasingly used for both classification and regression tasks. The aim of this work was to investigate the possibility of employing ML both to classify the most appropriate fit model and to predict the area under the curve (τ).

METHODS

Two different ML systems have been developed for classifying the fit model and to predict the biokinetic parameters. The two systems were trained and tested with synthetic TACs simulating a whole-body Fraction Injected Activity for patients affected by metastatic Differentiated Thyroid Carcinoma, administered with [131I]I-NaI. Test performances, defined as classification accuracy (CA) and percentage difference between the actual and the estimated area under the curve (Δτ), were compared with those obtained using AM varying the number of points (N) of the TACs. A comparison between AM and ML were performed using data of 20 real patients.

RESULTS

As N varies, CA remains constant for ML (about 98%), while it improves for F-test (from 62 to 92%) and AICc (from 50 to 92%), as N increases. With AM, [Formula: see text] can reach down to - 67%, while using ML [Formula: see text] ranges within ± 25%. Using real TACs, there is a good agreement between τ obtained with ML system and AM.

CONCLUSIONS

The employing of ML systems may be feasible, having both a better classification and a better estimation of biokinetic parameters.

PET/CT in congenital hyperinsulinism: transforming patient's lives by molecular hybrid imaging

Congenital hyperinsulinism (HI) is a life-threatening condition characterized by severe and recurrent episodes of hypoglycaemia due to defects in key genes involved in regulating insulin secretion. The delay in diagnosis and inappropriate management of HI lead to high risk of permanent hypoglycemic brain injury. The management of HI is challenging as each form of HI (focal, diffuse, and atypical) requires its own therapeutic strategy. In HI diagnostic work-up, integrated PET/CT scan is currently the first-line imaging technique allowing to differentiate between diffuse and focal form and, in the latter case, to localize the focus within the pancreas with high precision. Only in focal HI partial pancreatectomy is the treatment of choice and a curative surgical treatment means a real chance of transforming patient's lives and HI patient's future. The aim of this review is to discuss the role of PET/CT imaging in HI scenario, its technical advantages and limitations and how successful surgery is strongly dependent on accurate preoperative assessment (genetic analysis and PET/CT scan). A multidisciplinary approach in HI diagnosis and treatment inside a single team (involving different expertise) allows to manage children safely and properly, supporting their families in an organized care network.

Prognostic factors in children and adolescents with differentiated thyroid carcinoma treated with total thyroidectomy and RAI: a real-life multicentric study

PURPOSE

This multicentric study aimed to investigate the main prognostic factors associated with treatment response at 1 year after radioactive iodine therapy (RAIT) and the last disease status in pediatric patients affected by differentiated thyroid carcinoma (DTC).

MATERIALS AND METHODS

In the period 1990-2020, all consecutive patients ≤ 18 years from six different centers were retrospectively included. Patients were classified as low, intermediate, and high risk for persistence/recurrence. The response to RAIT was evaluated and scored 1 year later according to 2015 ATA guidelines. Moreover, at the last follow-up, the disease status was evaluated and dichotomized as no evidence of disease (NED) or persistent disease.

RESULTS

Two hundred and eighty-five patients (197 female, 88 male; mean age 14.4 years) were recruited. All, except nine, underwent near-total thyroidectomy followed by RAIT. One-year after first RAIT, 146/276 (53%) patients had excellent response, 37/276 (14%) indeterminate response, and 91/276 (33%) incomplete response. One-year after RAIT, children with excellent response had significantly lower stimulated thyroglobulin (sTg) compared to not excellent group (median sTg 4.4 ng/ml vs 52.5 ng/ml, p < 0.001). ROC curve showed sTg higher than 27.2 ng/ml as the most accurate to predict 1-year treatment response. After a median follow-up of 133 months, NED was present in 241 cases (87%) while persistent disease in 35 (13%). At multivariate analysis, sTg and 1-year treatment response categories were both significantly associated with the last disease status (p value 0.023 and < 0.001).

CONCLUSIONS

In pediatric DTC, sTg is significantly associated with 1-year treatment response and final outcome. However, 1-year response is the principal prognostic factor able to predict pediatric DTCs outcome.

Personalized dosimetry for a deeper understanding of metastatic response to high activity 131I-mIBG therapy in high risk relapsed refractory neuroblastoma

Background

Dosimetry in molecular radiotherapy for personalized treatment is assuming a central role in clinical management of aggressive/relapsed tumors. Relapsed/refractory metastatic high-risk neuroblastoma (rrmHR-NBL) has a poor prognosis and high-activity ¹³¹I-mIBG therapy could represent a promising strategy. The primary aim of this case series study was to report the absorbed doses to whole-body (D_WB ), red marrow (D_RM ) and lesions (D_Lesion ). A secondary aim was to correlate D_Lesion values to clinical outcome.

Methods

Fourteen patients affected by rrmHR-NBL were treated with high-activity ¹³¹I-mIBG therapy (two administrations separated by 15 days). The first administration was weight-based whereas the second one was dosimetry-based (achieving D_WB equals to 4 Gy). In all patients D_WB and D_RM was assessed; 9/14 patients were selected for D_Lesion evaluation using planar dosimetric approach (13 lesions evaluated). Treatment response was classified as progressive and stable disease (PD and SD), partial and complete response (PR and CR) according to the International Neuroblastoma Response Criteria. Patients were divided into two groups: Responder (CR, PR, SD) and Non-Responder (PD), correlating treatment response to D_Lesion value.

Results

The cumulative D_WB , D_RM and D_Lesion ranged from (1.5; 4.5), (1.0; 2.6) and (44.2; 585.8) Gy. A linear correlation between D_WB and D_RM and a power law correlation between the absorbed dose to WB normalized for administered activity and the mass of the patient were observed. After treatment 3, 2, 4 and 5 patients showed CR, PR, SD and PD respectively, showing a correlation between D_Lesion and the two response group.

Conclusions

Our experience demonstrated feasibility of high activity therapy of ¹³¹I-mIBG in rrmHR-NBL children as two administration intensive strategy. Dosimetric approach allowed a tailored high dose treatment maximizing the benefits of radionuclide therapy for pediatric patients while maintaining a safety profile. The assesment of D_Lesion contributed to have a deeper understaning of metabolic treatment effects.

Tandem high-dose 131I-MIBG therapy supported by dosimetry in pediatric patients with relapsed-refractory high-risk neuroblastoma: the Bambino Gesu' Children's Hospital experience

OBJECTIVE

131I-meta-iodobenzylguanidine (131I-MIBG) combined with myeloablative chemotherapy represents an effective treatment in children affected by relapsed/refractory neuroblastoma (NBL) for disease palliation and in improving progression-free survival. The aim of our study is to evaluate the feasibility, safety and efficacy of tandem 131I-MIBG followed by high-dose chemotherapy with Melphalan.

METHODS

Thirteen patients (age range: 3-17 years) affected by relapsed/refractory NB, previously treated according to standard procedures, were included in the study. Each treatment cycle included two administrations of 131I-MIBG (with a dosimetric approach) followed by a single dose of Melphalan with peripheral blood stem cell rescue.

RESULTS

At the end of the treatment, ten patients experienced grade 4 neutropenia, two grade 3 and one patient grade 2, three patients presented febrile neutropenia and all needed RBC and platelets transfusions; one patient presented grade 4 mucositis, four grade 3 and one patient grade 2 mucositis. One patient showed progressive disease, eight patients showed stable disease and four patients showed partial response.

CONCLUSION

High-dose 131I-MIBG therapy combined with chemotherapy represent a well-tolerated and effective modality of treatment in heavily pretreated patients affected by relapsed/refractory NBL. However, further studies, including a wider cohort of patients, are needed.

Predictive value of 18F-FDG PET/CT on survival in locally advanced rectal cancer after neoadjuvant chemoradiation

OBJECTIVE

To evaluate the prognostic value of 18F-FDG PET/CT in terms of survival in patients with locally advanced rectal cancer (LARC) who had undergone surgery preceded by neoadjuvant chemoradiotherapy (nCRT). Moreover, the existence of correlation between Overall Survival (OS) and Disease Free Survival (DFS) with pathological staging ((y)pTNM and TRG) was evaluated.

PATIENTS AND METHODS

A total of 58 patients with biopsy-proven of LARC were included. All patients underwent conventional diagnostic/staging procedures to characterize the rectal lesion. The first whole-body 18F-FDG PET/CT was performed 1 week before the beginning of nCRT (baseline scan). The second 18F-FDG PET/CT was scheduled at 5-6 weeks from nCRT completion (post-nCRT scan). Survival was evaluated in 3 different restaging classification systems, based on focusing only on primary lesion (TRG), loco-regional evaluation (ypTNM) and whole-body 18F-FDG PET/CT evaluation (VRA).

RESULTS

Among the 58 patients at the end of the observation, 46/58 patients (79.3%) were alive and 12/58 (20.7%) were dead. This work demonstrated a higher percentage of patients with TRG complete response (39.7%) compared to literature (24.6%), with longer Overall Survival (OS) and Disease Free Survival (DFS) in responders even if without statistically significant differences.

CONCLUSIONS

The present study highlights the predictive and prognostic potential role of 18F-FDG PET/CT in assisting physicians on personalized decision in the selective risk-adapted treatment strategy, and to schedule the correct follow-up approach.

99mTc-diphosphonates bone scintigraphy for vitality evaluation in cleft palate

Cleft of the lip, palate and alveolus are congenital oro-maxillofacial malformation with an established treatment protocol. At present, there is great interest in the alveolar bone grafting procedures that involve the use of platelet-rich-plasma (PRP), to enhance bone formation and specifically to promote bone graft healing in head and neck tissues regeneration. The aim of this retrospective case report study was to assess the condition and viability of the standard bone grafting in association with PRP (platelet rich plasma) to enhance osteogenesis and maintain osteointegration in alveolar cleft with a follow up of eight years from the surgical procedure. The viability of bone grafts was documented by means of head bone scintigraphy (99mTc-MDP). The scintigrams revealed the decreased uptake at the cleft region and the increased uptake at the adjacent alveolus of the cleft. From these findings we suggest that platelet concentrates decrease the need of further surgical intervention in cleft palate patients. In addition, scintigraphy may be useful to evaluate postoperative bone formation in the alveolar cleft.

Impact of pre-treatment variables on the completion of 223radium-dichloride therapy in mCRPC patients with bone metastases

INTRODUCTION

Radium-223 dichloride (²²³Ra) is an alpha-particle-emitter radiopharmaceutical, approved for metastatic castration-resistant prostate cancer (mCRPC) patients with symptomatic bone metastases and no visceral involvement. Its administration is based on a schedule of intravenous injection (55kBq/kg) every four weeks for up to six cycles. Because the biological effectiveness of ²²³Ra-therapy is dose-dependent, the main goal is to complete the entire treatment to achieve a better patient outcome. This study aims to identify potential pre-treatment variables that could impact on ²²³Ra-treatment completion and then be used to improve the clinical and supportive management of mCRPC patients.

MATERIALS AND METHODS

30 consecutive mCRPC patients (mean age 77 years old), who were admitted for Ra223-therapy at our Department from February 2016 to October 2018, were enrolled for the analysis. The population was grouped as patients who completed ²²³Ra-therapy (group Ra223-C) and patients who do not (group ²²³Ra-U). For each group, we analyzed the effects of potential pre-treatment variables (age, Gleason Score, tumor burden, "Time From Diagnosis To ²²³Ra therapy", type and number of previous treatments, hemoglobin level, Alkaline Phosphatase, Prostate Specific Antigen and pain) on the Ra223-therapy completion. Statistical analysis was performed to evaluate the association between the completion of ²²³Ra therapy and the variables examined.

RESULTS

16/30 (53%) patients were ²²³Ra-C, conversely 14/30 (47%) patients were ²²³Ra-U because of an early interrupted treatment. A statistically significant association was found only with tumor burden: 68.7% of patients who completed ²²³-therapy had less than 20 bone metastases (χ²=4.821, p=0.028).

CONCLUSION

Our preliminary analysis demonstrates that the high tumor burden represents the most important pre-treatment factor that could affect treatment completion and that needs to be considered before starting ²²³Ra-therapy to achieve a better outcome in mCRPC patients.

The paleoradiology importance in the study of relics: the unique densitometric analysis of a bone relic of Saint Nicholas

INTRODUCTION

DXA have greatly contributed to the development of paleoradiology, a branch of diagnostic imaging that allows to obtain information about human remains in contexts of archaeological and/or forensic interest. In this manuscript we report the unique experience of DXA performed on the relic of a Saint; in particular we analyzed a skeletal fragment of St. Nicholas, kept in the Basilica of Bari (Italy) since 1087.

MATERIALS AND METHODS

The bone to be examined consisted of the posterior arch of the ninth left rib that was 12cm long, 1.2cm maximum width and 1.7cm thick at the body. The data acquired from the densitometric study were performed using the anthropometric measures reported in historical records of St. Nicholas' life: sex (male), age (75 years), weight (70kg), height (167cm), and ethnicity (Caucasian). In addition to the examination of the relic, a comparison assessment was made with the rib of a healthy 60 years old man (height of 170cm, without known skeletal pathologies). This sample had a length of 19cm, maximum width at the head 1cm, and 0.7cm thick at the body. The analysis of bone fragments is different from the analysis of bones in the context of the human body (where soft tissues are placed around the skeleton); for this reason, one of the most critical issues was to create a support that would allow the analysis of bone fragments. We simulated conditions similar to those occurring in patients: a density scale was established, using a specific plexiglass phantom on which the bone fragments to be examined were placed. From the analysis it was calculated the parameter bone mineral density (BMD), express in g/cm², that indicates the relation between mass of bone mineral content and area of examined bone segment. BMD data was compared to a range normalized by age, sex and ethnicity (BMD-N).

RESULTS

The results of the scannnig of St. Nicholas' rib showed a BMD of 0.97g/cm² with a BMD-N between 0.77 and 1.08g/cm². Simultaneous measurements of the relic compared with a reference rib showed highlighted BMD of 0.84g/cm² for the relic and 0.50g/cm² for the reference rib. The St. Nicholas data are 168% higher than reference bone. All our measurements of the relic indicated a high bone mineral density, most likely due to the presence of a high concentration of calcium salts. A relatively higher mineral density of the relic was seen compared to the healthy subject's rib. From the history of St Nicholas' life, we know of the long imprisonment at the age of 51 in damp and unhealthy environment. The results of this study suggest that a good bone mineral density was maintained by the Saint even in old age. An additional element that can influence bone mineral density is diet, certainly different during the time of St. Nicholas. The good bone densitometry indicates that the Saint maintained a proper diet, with a generally fair state of health.

CONCLUSION

For this first DXA analysis of the rib relic of Saint Nicholas was necessary a long and complex experimental work to modify standard technique procedure to particular and unusual sample and Create specific supports and complementary instruments. Perform DXA analysis on relics permit to obtain additional information to living conditions, economical situation, behaviours, diet, diseaes, conservations conditions of remains, change of life style in different age. Our experimental work, the first of its kind, creates the way to analyze precious relics that often include only few bone fragments and data obtained by our work can be useful for a better management and movement of fragile relics. We ourselves are working on a new challenge for the analysis of bone finds from shipwrecks found at the bottom of the sea.

18F-FDG Positron Emission Tomography/Computed Tomography in the Diagnosis and Post-Therapeutic Treatment in a Patient with an Early Stage of Retroperitoneal Fibrosis

Here, we report an experience about 18F-FDG-PET/CT in a patient with an early stage of Idiopathic Retroperitoneal Fibrosis (IRF). At the diagnosis Contrast Enhanced Computed Tomography (CE-CT) revealed periaortic solid tissue in the infrarenal section and locoregional lymph nodes; findings were interpreted as lymphomatous tissue. 18F-FDG-PET/CT showed elevated 18F-FDG uptake in the periaortic tissue but no uptake was detected in lymph nodes. The histologic examination showed recent-onset IRF. The patient began corticosteroid therapy. Nearly at the end of the therapy, CE-CT showed the enlargement of the fibrous tissue and 18F-FDG-PET/CT showed an increased 18F-FDG uptake in the aforesaid lesion and another area of uptake in the aortic wall. 18F-FDG-PET/CT can play an important role in the diagnosis of patients with an initial clinical suspicion of retroperitoneal fibrosis and in their management. Then the patient began a therapy with methotrexate and after six months we performed an 18F-FDG-PET/CT which didn’t show 18F-FDG uptake.

Conflict of interest:None declared.