Radiation Absorbed Dose to the Embryo and Fetus from Radiopharmaceuticals

Clinical Translation of a Dual-Integrin αvβ3- and CD13-Targeting PET Tracer

PURPOSE

Angiogenesis is essential in the development and progression of tumors. This study aimed to investigate the clinical application of 68 Ga-labeled heterodimeric peptide ( 68 Ga-HX01) targeting integrin αvβ3 and CD13 in tumor neovascularization.

PATIENTS AND METHODS

Six healthy volunteers were recruited to study the biodistribution, pharmacokinetics, and radiation of 68 Ga-HX01. Twelve patients with various malignancies were enrolled to seek the preliminary clinical value of 68 Ga-HX01. In healthy volunteers, SUVs of each major organ on 68 Ga-HX01 PET were measured. The clinical data, lesion numbers, and uptake were recorded in patients. The integrin αvβ3 and CD13 expression of the resected tumors was checked via immunohistochemistry staining.

RESULTS

With a mean injected dose of 167.98 ± 26.32 MBq, 68 Ga-HX01 was well tolerated and safe without side effects in 6 healthy volunteers. The radiation absorbed effective dose of 68 Ga-HX01 was 1.94 × 10 -2 mSv/MBq, and the urinary bladder wall held the highest absorbed effective dose (0.15 ± 5.87 × 10 -2 mSv/MBq). In 12 patients with various malignancies, 68 Ga-HX01 PET could clearly visualize the lesions from the surrounding tissues. The SUV max values in tumors were significantly higher than those in the surrounding tissues ( P < 0.05). A positive correlation trend between tumor SUV max and semiquantitative integrin αvβ3 and CD13 expression was determined ( P < 0.05).

CONCLUSIONS

For clinical use, 68 Ga-HX01 is safe with low radiation absorbed effective dose. It also indicates the efficiency of dual integrin αvβ3 and CD13-targeting PET radiotracer in tumor diagnosis, which may assist in patient prognosis and selecting eligible patients for antiangiogenic therapy.

EANM practice guidelines for an appropriate use of PET and SPECT for patients with epilepsy

Epilepsy is one of the most frequent neurological conditions with an estimated prevalence of more than 50 million people worldwide and an annual incidence of two million. Although pharmacotherapy with anti-seizure medication (ASM) is the treatment of choice, ~30% of patients with epilepsy do not respond to ASM and become drug resistant. Focal epilepsy is the most frequent form of epilepsy. In patients with drug-resistant focal epilepsy, epilepsy surgery is a treatment option depending on the localisation of the seizure focus for seizure relief or seizure freedom with consecutive improvement in quality of life. Beside examinations such as scalp video/electroencephalography (EEG) telemetry, structural, and functional magnetic resonance imaging (MRI), which are primary standard tools for the diagnostic work-up and therapy management of epilepsy patients, molecular neuroimaging using different radiopharmaceuticals with single-photon emission computed tomography (SPECT) and positron emission tomography (PET) influences and impacts on therapy decisions. To date, there are no literature-based praxis recommendations for the use of Nuclear Medicine (NM) imaging procedures in epilepsy. The aims of these guidelines are to assist in understanding the role and challenges of radiotracer imaging for epilepsy; to provide practical information for performing different molecular imaging procedures for epilepsy; and to provide an algorithm for selecting the most appropriate imaging procedures in specific clinical situations based on current literature. These guidelines are written and authorized by the European Association of Nuclear Medicine (EANM) to promote optimal epilepsy imaging, especially in the presurgical setting in children, adolescents, and adults with focal epilepsy. They will assist NM healthcare professionals and also specialists such as Neurologists, Neurophysiologists, Neurosurgeons, Psychiatrists, Psychologists, and others involved in epilepsy management in the detection and interpretation of epileptic seizure onset zone (SOZ) for further treatment decision. The information provided should be applied according to local laws and regulations as well as the availability of various radiopharmaceuticals and imaging modalities.

Lifetime attributable risks (LARs) of cancer in the fetus associated with maternal radiography examinations

PURPOSE

For various reasons, pregnant women are occasionally exposed to ionizing radiation during radiology examinations. In these situations, it is essential to determine the radiation dose to the fetus and any associated risks. The present study attempts to calculate the mean dose for the fetus to estimate the possible cancer induction and cancer mortality risks resulting from maternal radiography exams.

MATERIAL AND METHODS

The GATE Monte Carlo platform and a standard voxelized pregnant phantom were employed to calculate fetal radiation dose during maternal radiography exams. The data published in Biological Effects of Ionizing Radiation VII were used to convert fetal dose to lifetime attributable risks (LARs) of cancer incidence and cancer-related mortality.

RESULTS

The fetal doses and LARs of cancer incidence and cancer-related mortality for the radiographs of the chest and skull were negligible. The maximum LAR values for the lateral view of the abdomen in computed and digital radiography are 5598.29 and 2238.95 per 100,000 individuals, respectively. The computed radiography of the lateral view of the abdomen revealed the highest LAR of cancer-related mortality (2074.30 deaths for every 100,000 people).

CONCLUSION

The radiation dose incurred by the fetus due to chest and skull radiographs was minimal and unlikely to cause any abnormalities in the fetus. The discernible elevation in the lifetime attributable risk associated with cancer incidence and mortality arising from lateral computed radiography examinations of the abdomen warrants careful consideration within the realm of maternal radiography examinations.

Medicolegal considerations associated with cancer during pregnancy

The management of pregnant patients with cancer is complex and requires a multidisciplinary team to effectively diagnose, stage, and manage the cancer while also being cognizant of the potential harm that diagnosis and treatment may have on the maternal and fetal well-being. Beyond the complex clinical management of these patients is additional medicolegal consideration. Radiologists play a crucial role in the management of these patients as their knowledge of diagnostic and interventional radiology techniques allows for appropriate and safe imaging for both the mother and fetus. In addition, radiologist are able to educate patient on the different imaging modalities and techniques, thus allowing patients to make informed decisions and maintain autonomy over there care. This article will review safety considerations associated with different imaging modalities, contrast agents, interventional radiology procedures and moderate sedation related to the imaging of pregnant patient with cancer with specific attention paid to the medicolegal aspects.