Fetal Dosimetry at CT: A Primer

CT angiography for characterization of advanced placenta accreta spectrum: indications, risks, and benefits

Placenta accreta spectrum disorder (PASD) encompasses various types of abnormal placentation in which chorionic villi directly adhere to or invade the myometrium. The incidence of PASD has dramatically risen in the US over the past 3 decades owing to the increased rates of patients undergoing cesarean sections. While PASD remains a significant cause of maternal morbidity and mortality, accurate prenatal identification and characterization of PASD is associated with improved outcomes. Although ultrasound is the first-line imaging modality in the evaluation of PASD, with MRI serving as an adjunct, computed tomography angiography (CTA) may also offer unique diagnostic advantages in cases of advanced PASD by providing superior visualization of placental and abdominopelvic vasculature and enabling the creation of comprehensive vascular maps to roadmap complex surgical interventions. This paper represents the first evaluation of CTA as a diagnostic tool and operative planning aid in this context. Appropriate indications and diagnostic advantages of CTA in this setting are reviewed, and key multimodal imaging features of normal and abnormal placentation are highlighted.

A pregnant woman with long-standing, retained intraabdominal glass shards who gave birth to a live infant with no complications: a case report

BACKGROUND

Most cases of traumatic injury during pregnancy involve blunt trauma, with penetrating trauma being uncommonly rare. In glass shard injuries, fragments often penetrate deeply, and multiple injuries may occur simultaneously; attention must be paid to the possibility of organ injury from the residual fragments. However, no case of this occurring during pregnancy has been reported yet.

CASE PRESENTATION

We present the case of a 34-year-old pregnant Cameroonian woman who retained intraabdominal glass shards following a penetrating injury at 13 weeks gestation and not diagnosed until 22 weeks gestation. Notably, this patient continued the pregnancy without complications and gave birth via cesarean section at 36 weeks gestation.

CONCLUSION

In pregnant women sustaining a penetrating glass trauma during pregnancy, careful attention should be paid to the fragments; in that case, computed tomography is a useful modality for accurately visualizing any remaining fragments in the body. Essentially, the foreign bodies in glass shard injuries during pregnancy should be removed immediately, but conservative management for term delivery is an important choice for patients at risk for preterm delivery.

Spontaneous haemoperitoneum in the second trimester of pregnancy

This is a case of a spontaneous haemoperitoneum occurring in the second trimester of pregnancy which was managed with interventional radiology to avoid laparotomy and its potential consequences. We aim to raise awareness of this condition in pregnancy because the perinatal mortality rate is as high as 36%. Spontaneous haemoperitoneum in pregnancy (SHiP) has frequently been associated with vascular rupture from pre-existing endometriosis. Most cases of SHiP have been managed with laparotomy. However, transcatheter embolisation can impart lifesaving alternatives to more invasive interventions when caring for pregnant patients. More judicious use of imaging procedures may also help improve diagnostic and therapeutic pathways with SHiP. We recommend that high-risk pregnancies are managed in level IV regional perinatal healthcare centres, when possible, where subspecialists and alternative measures of management exist.

Initial Imaging of Pregnant Patients in the Trauma Bay-Discussion and Review of Presentations at a Level-1 Trauma Centre

Trauma is the leading non-obstetric cause of maternal and fetal mortality and affects an estimated 5-7% of all pregnancies. Pregnant women, thankfully, are a small subset of patients presenting in the trauma bay, but they do have distinctive physiologic and anatomic changes. These increase the risk of certain traumatic injuries, and the gravid uterus can both be the primary site of injury and mask other injuries. The primary focus of the initial management of the pregnant trauma patient should be that of maternal stabilization and treatment since it directly affects the fetal outcome. Diagnostic imaging plays a pivotal role in initial traumatic injury assessment and should not deviate from normal routine in the pregnant patient. Radiographs and focused assessment with sonography in the trauma bay will direct the use of contrast-enhanced computed tomography (CT), which remains the cornerstone to evaluate the potential presence of further management-altering injuries. A thorough understanding of its risks and benefits is paramount, especially in the pregnant patient. However, like any other trauma patient, if evaluation for injury with CT is indicated, it should not be denied to a pregnant trauma patient due to fear of radiation exposure.

Management of pregnant or potentially pregnant patients undergoing diagnostic and interventional radiology procedures: Investigation of clinical routine practice

It is well known that foetuses are highly sensitive to ionising radiation and special attention to justification and optimisation of radiological procedures involving a pregnant patient is required. A task to review, validate and compare different approaches to managing the pregnant patient and to estimating the associated foetal doses arising from a diagnostic or interventional radiology (DIR) procedure was designed in the framework of EURADOS working group 12. As a first step, a survey of radiation protection practice including dosimetry considerations among EURADOS members was performed using online questionnaire. Then, to evaluate the possible differences in the estimated foetal doses, a comparison of assessed dose values was made for three cases of pregnant patients that underwent different CT procedures. More than 120 professionals from 108 institutions and 17 countries that are involved in managing pregnant patients undergoing DIR procedures answered the questionnaire. Most of the respondents use national or hospital guidelines on the management of pregnant patients undergoing DIR procedures. However, the guidelines differ considerably among respondents. Comparison of foetal dose assessments performed by dosimetry experts showed the variety of methods used as well as large variability of estimated foetal doses in all three cases. Although European and International commission on radiation protection guidelines already exist, they are more than 20 years old and, in some aspects, they are obsolete. This paper shows that there is a need to revise and update these guidelines.

Reconsidering pregnancy screening policies for minors: patient-specific estimate of fetus and effective dose for potentially pregnant minors undergoing optimized dose CT of the pelvis

BACKGROUND

Only verbal pregnancy screening is recommended for post-menarcheal females undergoing pelvic radiographs. In contrast, usually, a urine/serum pregnancy test for pelvic computed tomographic (CT) exams is required out of concern for higher radiation exposure.

OBJECTIVE

To estimate patient-specific fetus absorbed dose to a potentially pregnant minor from an optimized dose CT of the pelvis for femoral version and surgical planning and provide evidence that such examinations of the pelvis can be performed with only verbal pregnancy screening.

METHODS AND METHODS

A retrospective study was performed on 102 female patients between 12-18 years of age (15.4 ± 2.1 years) who underwent optimized dose CT of the pelvis for orthopedic evaluation of femoral version and surgical planning. Optimized CT exams were performed with weight-adjusted kVp and tube current modulation. Patient-specific dose from the optimized dose CT was calculated using the National Cancer Institute Dosimetry System for CT (NCICT) database by matching each patient to a phantom from the NCI non-reference phantom library based on patient sex, weight, and height. The calculated absorbed uterus dose was used as a surrogate for the fetus dose. Furthermore, patient-specific organ doses were used to estimate the effective dose. The strengths of the linear relationships between the dose metrics and patient characteristics were assessed using Pearson correlation coefficients through linear regression.

RESULTS

The mean patient-specific effective dose for an optimized dose CT of the pelvis was 0.54 ± 0.20 mSv (range: 0.15-1.22 mSv). The mean estimated absorbed uterine dose was 1.57 ± 0.67 mGy (range: 0.42-4.81 mGy). Both effective dose and estimated uterine dose correlated poorly with patient physical characteristics (R = -0.26; 95% CI: [-0.43, -0.007] for age, R = 0.03; 95% CI: [-0.17, 0.22] for weight) but correlated strongly (R = 0.79, 95% CI: [0.7, 0.85]) with CTDIvol.

CONCLUSION

The estimated fetus dose in case of pregnancy was significantly lower than 20 mGy for urine/serum pregnancy screening, suggesting that the pregnancy screening protocols in minors undergoing optimized dose CT require reassessment and may be safely performed by verbal attestation only.

Acute abdomen caused by spontaneous rupture of degenerative hysteromyoma during pregnancy: A case report

BACKGROUND

Hysteromyoma is not a rare tumor among pregnant women. During pregnancy, the symptoms caused by hysteromyoma can be improved through conservative treatment in most cases. However, in order to ensure the safety of mothers and children, surgeries are necessary in some special cases.

CASE SUMMARY

We report a case of pregnancy complicated with hysteromyoma red degeneration. The patient had peritonitis after sudden abdominal pain during the 20^th week of pregnancy. Laparoscopic exploration suggested rupture and bleeding of hysteromyoma, which were improved after drainage and an anti-inflammatory treatment. A cesarean section was performed after full term. This case shows the complications of rupture after red degeneration of hysteromyoma during pregnancy.

CONCLUSION

We should be alert to rupture of hysteromyoma during pregnancy, and active laparoscopic exploration is essential to improve the prognosis of such patients.

Imaging Cancer in Pregnancy

Pregnancy-associated cancer (PAC) is defined as cancer that is detected during pregnancy and up to 1 year postpartum. Although rare (~1:1000 pregnancies), PAC is increasing owing to postponed childbearing and advanced maternal age at conception. Cancer-related symptoms masked by physiologic gestational changes may delay diagnosis. Imaging, clinical management, and treatment require a carefully choreographed multidisciplinary team approach. The risk-benefit of every imaging modality, the strategies to balance the safety of mother and fetus, and the support of the patient and family at every step are crucial. US and MRI are preferred imaging modalities that lack ionizing radiation. Radiation dose concerns should be addressed, noting that most imaging examinations (including mammography, radiography, CT, and technetium 99m-labeled sulfur colloid sentinel lymph node staging) are performed at radiation levels below thresholds at which deterministic side effects are seen. Dose estimates should be provided after each examination. The use of iodinated intravenous contrast material is safe during pregnancy, but gadolinium-based contrast material should be avoided. Accurate diagnosis and staging combined with gestational age affect decisions about surgery and chemotherapy. Whole-body MRI with diffusion-weighted sequences is ideal to screen for primary and metastatic sites, determine disease stage, identify biopsy targets, and guide further cancer site-specific imaging. The authors provide an update of the imaging triage, safety considerations, cancer-specific imaging, and treatment options for cancer in pregnancy. An invited commentary by Silverstein and Van Loon is available online. Online supplemental material is available for this article. ^©RSNA, 2022.

Embryo/Fetus Doses from 18F-Fludeoxyglucose Radiopharmaceutical in Positron Emission Tomography/ Computed Tomography

Aim

The embryo/fetus may be accidentally exposed to ionizing radiation. The aim of this study is to calculate embryo/fetus doses in pregnant women who underwent F-18 fludeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) scan.

Materials and Methods

Between June 2015 and June 2021, 15 pregnant women underwent F-18 FDG PET/CT applied to the Genetic Research Center (GETAM). The OLINDA/EXM package program was used for internal radiation dosimetry according to the Medical Internal Radiation Dose scheme. FetDose V4 computer software was used to compute the embryo/fetus absorbed dose from CT scan.

Results

The amount of the injected F-18 FDG activity to patients varied between 333 and 555 MBq. The mean embryo/fetal dose from F-18 FDG was 7.2 ± 2.8 mGy. In addition, the CT component dose to the embryo/fetus dose ranged from 8.5 to 16 mGy with a mean of 12.14 ± 2.05.

Conclusions

The embryo/fetus dose from F-18 FDG PET/CT was <15 mGy, however, questioning the women's childbearing prior to scintigraphy is the first-line strategy to avoid accidental radiation exposure and stochastic risks.

[The (severely) injured pregnant patient from the perspective of radiology]

Trauma is one of the leading causes of mortality in pregnant women and significantly increases the likelihood of an unwanted termination of pregnancy. Particularly in severe trauma with an increased risk of significant maternal injuries, computed tomography (CT) remains the imaging modality of choice as it is comprehensively available, quick to carry out and has a high diagnostic accuracy in the detection and classification of life-threatening trauma-associated pathologies compared to other imaging techniques. Considering the radiation-associated risks, it is unlikely that a single, monophasic CT in the emergency trauma room will exceed the threshold of deterministic radiation damage; therefore, fetal malformations or fetal loss are not to be expected; however, there is a low stochastic risk for the delayed occurrence of radiation-induced cancer both for the child and the mother that can be considered small in comparison to missed or delayed diagnoses after severe trauma. Intravenous, nonionic iodinated contrast agents are not contraindicated during pregnancy and should be administered whenever their use would also be considered appropriate in a nonpregnant patient; however, unnecessary scans and, if possible, multiple contrast agent phases should be avoided in order to reduce radiation. Magnetic resonance imaging (MRI) has a major role in the subacute setting and constitutes an excellent problem solver for specific questions, such as the evaluation of discoligamentous injuries of the spine. Its use is deemed acceptable at any stage of pregnancy when the required information is considered important for the management of further treatment. Due to potential teratogenic effects of MRI contrast media containing gadolinium on the fetus, including an increased likelihood of fetal loss, they should only be administered with great caution and under strictly defined indications.