MR imaging in the triage of pregnant patients with acute abdominal and pelvic pain

Imaging the pregnant patient with abdominal pain

Imaging of pregnant patients with non-obstetric abdominal pain is reviewed, with an accompanying pictorial essay of cases with concentration on magnetic resonance imaging. Non-obstetric causes of abdominal pain during pregnancy are similar to those of non-pregnant patients. The most common causes are appendicitis and cholecystitis. Other causes are myriad and include biliary, gastrointestinal, infectious, inflammatory, and malignant etiologies, among others. The approach to imaging in pregnant patient is unique, as it is imperative to minimize potentially harmful radiation exposures to the fetus. Ultrasound and MRI are the primary modalities for evaluation of the pregnant patient with abdominal pain. The use of intravenous contrast is discouraged, except in highly-selected patients where there is no other way to obtain vital diagnostic information. CT is still used as the mainstay of evaluation of blunt abdominal trauma and is commonly used for diagnosis of small bowel obstruction, stone disease, and work-up of malignancy during pregnancy. A discussion of test selection and underlying rationale is presented.

Hepatobiliary scintigraphy in acute cholecystitis

Hepatobiliary scintigraphy is a mature imaging technique for evaluation of patients with acute cholecystitis (AC). It is effective in calculous and acalculous forms of AC. The test is used in contemporary medical practice as the arbiter when the findings from screening abdominal ultrasound do not fit a clinical picture. It is also performed in severely ill patients who have AC suspected on other testing, but whose frail condition and high operative risk demand the highest level of certainty. This review, therefore, examines all technique variations of hepatobiliary scintigraphy, offering an approach that may best fit a variety of clinical situations and philosophies on AC.

Ultrafast 3-T MRI in the evaluation of children with acute lower abdominal pain for the detection of appendicitis

OBJECTIVE

The purpose of this study is to evaluate the feasibility of ultrafast 3-T MRI in the evaluation of children with acute lower abdominal pain for the detection of appendicitis.

SUBJECTS AND METHODS

Forty-two pediatric patients (30 girls and 12 boys; mean age, 11.5 years; age range, 4-17 years) with acute abdominal pain were prospectively studied. Ultrafast 3-T MRI was performed with a three-plane single-shot turbo spin-echo sequence and an axial T2-weighted turbo spin-echo sequence with fat suppression. All scans were performed without sedation or oral or IV contrast agent. Scan times were less than 8 minutes 45 seconds (median, 5 minutes 40 seconds). Patients underwent CT or ultrasound or both as a comparison study to the MRI examination. The MRI, CT, and ultrasound examinations were interpreted independently by four board-certified radiologists who were blinded to patient information, study interpretations, surgical pathologic findings, and final diagnosis.

RESULTS

Twelve of 42 cases of acute appendicitis were detected with 100% sensitivity, 99% specificity, 100% negative predictive value, and 98% positive predictive value, all of which were statistically significant (p < 0.01). The pooled and individual receiver operating characteristic curves for radiologists' interpretation of the diagnosis of acute appendicitis were greater than 0.95 in all cases (p < 0.01)

CONCLUSION

Ultrafast 3-T MRI is a feasible alternative imaging modality for the diagnosis of acute appendicitis in children, particularly in cases where ultrasound is equivocal or nondiagnostic, as an alternative to CT. Ultrafast MRI requires no sedation and no oral or IV contrast agent and has no associated radiation exposure risks.

Acute appendicitis and adverse pregnancy outcomes: a nationwide population-based study

BACKGROUND/OBJECTIVE

Acute appendicitis is the most common non-obstetric surgical procedure in pregnant women. Using two large-scale nationwide population-based datasets, this study aimed to assess the risk of adverse pregnancy outcomes between mothers with and without appendicitis in Taiwan.

METHODS

This study used two nationwide population-based datasets: the Taiwan National Health Insurance Research Dataset and the Taiwan national birth certificate registry. This study included 908 women who had live singleton births and who had been hospitalized with a diagnosis of acute appendicitis, and another randomly selected 4,540 women as a comparison group. Conditional logistic regression analyses were performed to calculate the risk of adverse pregnancy outcomes including low birth weight (LBW), preterm birth, small for gestational age (SGA), cesarean section (CS), congenital anomalies, Apgar scores at 5 min (<7), and pre-eclampsia/eclampsia.

RESULTS

The adjusted odds ratios for LBW, preterm birth, SGA, CS, and congenital anomalies in women with acute appendicitis were 1.82 (95 % CI = 1.43-2.30), 1.59 (95 % CI = 1.25-2.02), 1.33 (95 % CI = 1.12-1.60), 1.24 (95 % CI = 1.07-1.44), and 2.07 (95 % CI = 1.07-4.03), respectively, compared with women without acute appendicitis after adjusting for highest maternal educational level, marital status, geographic region, gestational diabetes, gestational hypertension, coronary heart disease, anemia, hyperlipidemia, obesity, and alcohol abuse/alcohol dependence syndrome, infant sex and parity, and paternal age.

CONCLUSIONS

There were increased risks for having LBW, preterm infants, SGA, congenital anomalies, and for experiencing CS among women with acute appendicitis than comparison women.

Imaging of pregnant and lactating patients: part 1, evidence-based review and recommendations

OBJECTIVE

The objectives of this article are to discuss the current evidence-based recommendations regarding radiation dose concerns, the use of iodinated and gadolinium-based contrast agents, and the comparative advantages of multimodality imaging (ultrasound, CT, and MRI) during pregnancy and lactation. We also discuss the use of imaging to evaluate pregnant trauma patients.

CONCLUSION

Maternal and fetal radiation exposure and dose are affected by gestational age, anatomic site, modality, and technique. The use of iodinated and gadolinium-based contrast agents during pregnancy and lactation has not been well studied in human subjects. Imaging should be used to evaluate pregnant trauma patients only when the benefits outweigh the risks.

ACR Appropriateness Criteria® right lower quadrant pain--suspected appendicitis

The diagnostic imaging of patients presenting with right lower quadrant pain and suspected appendicitis may be organized according to age and gender and to the presence or absence of "classic" signs and symptoms of acute appendicitis. Among adult patients presenting with clinical signs of acute appendicitis, the sensitivity and specificity of CT are greater than those of ultrasound, with improved performance when CT is performed with intravenous contrast. The use of rectal contrast has been associated with decreased time in the emergency department. Computed tomography has also been shown to reduce cost and negative appendectomy rates. Both CT and ultrasound are also effective in the identification of causes of right lower quadrant pain unrelated to appendicitis. Among pediatric patients, the sensitivity and specificity of graded-compression ultrasound can approach those of CT, without the use of ionizing radiation. Performing MRI after inconclusive ultrasound in pregnant patients has been associated with sensitivity and specificity of 80% to 86% and 97% to 99%, respectively. The ACR Appropriateness Criteria(®) are evidence-based guidelines for specific clinical conditions that are reviewed every 2 years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer-reviewed journals and the application of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In those instances in which evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.

Is administration of gadolinium-based contrast media to pregnant women and small children justified?

The use of gadolinium-based contrast media in pregnant or lactating women has been discouraged at many radiology departments due to the lack of knowledge of the risks for the fetus and the unwillingness to expose neonates to unnecessary drugs. In the present review the current literature and present guidelines regarding the use of gadolinium-based contrast media have been reviewed to validate the justification for their administration to pregnant or lactating women and small children.

Internal herniation through the foramen of Winslow during pregnancy: MR findings [corrected]

We present a unique case of jaundice in pregnancy, secondary to common bile duct obstruction by an unusual internal colonic hernia. We also illustrate the benefits of using non-ionizing imaging modalities in the diagnosis and pre-operative planning of this rare condition.

[Acute non-obstetrical diseases during pregnancy and role of the obstetrician]

The management of a pregnant woman with an acute non-obstetrical disease must be made in narrow collaboration with an obstetrician. This one must be warned from the beginning of the care of the patient. In a pregnant woman, any acute medical, surgical or traumatic non-obstetrical disease can have obstetrical consequences. The diagnostic and therapeutic management of an acute non-obstetrical disease can have iatrogenic consequences during pregnancy. The most often described risks are early pregnancy loss, intra-uterine fetal death, placenta abruption, direct fetal hurts, preterm labor, prematurity and its complications. Obstetrical complications can induce maternal and neonatal life-threatening risks. Simple and easily accessible examinations in emergency allow detecting the obstetrical consequences of an acute non-obstetrical disease. During the management of an acute non-obstetrical disease in a pregnant woman, the induced obstetrical consequence of the disease can require emergency action of the obstetrician in conditions associated with maternal life-threatening risk. During the management of an acute non-obstetrical disease in a pregnant woman, once the mother condition was stabilized, the obstetrician had to estimate the fetal consequences and to adapt his or her therapeutic attitude. He or she sets up the fetal and placental surveillance adapted to the obstetrical risks and decides on the duration of this surveillance.

Magnetic resonance imaging for the evaluation of acute abdominal pain in pregnancy

The investigation of acute abdominal pain in pregnancy is challenging. The use of ultrasound may be limited due to the patient's change in body habitus and computed tomography is not desirable due to fetal irradiation. Magnetic resonance imaging (MRI) has thus become increasingly popular in the evaluation of such patients, due to its lack of ionizing radiation, multiplanar capability and high contrast resolution. This review will detail the MRI technique required to image the pregnant abdomen and describe the MRI features of common causes of acute abdominal pain in pregnancy.

Magnetic resonance imaging and ultrasonography in diagnosis of pelvic vein thrombosis during pregnancy

INTRODUCTION

Pelvic deep vein thrombosis (DVT) is difficult to diagnose during pregnancy. In a two-center trial, we evaluated the agreement between ultrasonography and magnetic resonance imaging (MRI) in diagnosing the extent of DVT into the pelvic veins during pregnancy.

MATERIALS AND METHODS

Pregnant women with proximal DVT were examined both with ultrasound and MRI as part of a study designed for treatment of DVT during pregnancy. Ultrasound was performed using color flow by specialist in vascular ultrasound with Doppler and compression techniques. The MRI sequences consisted of a 2D Time of Flight angiography with arterial flow suppression and maximum intensity projection reconstructions; a 3D, T1-w-prepared gradient echo sequence with fat saturation for thrombus imaging; a steady-state free precession sequence; and a Turbo-Spin-Echo. No contrast agent was used. Proportion of agreement (kappa) for detection of DVT in individual veins was measured for different ipsilateral veins and inferior vena cava.

RESULTS

All 27 patients were imaged with both techniques at an average gestational age of 29 weeks (range 23-39). Three cases (11.5%) of DVT in the pelvic veins were missed on ultrasound but detected by MRI. The upper limit of the DVT was always depicted at a higher (20 cases, 65.4%) or the same level (seven cases, 34.6%) on MRI than on ultrasound. Agreement expressed as kappa was 0.33 (95% CI 0.27-0.40) demonstrating only fair agreement. In one woman the thrombus had propagated into the inferior vena cava, shown only on MRI.

CONCLUSION

Our study suggests that in pregnant women there is only fair agreement between ultrasound and MRI for determination of extent of DVT into pelvic veins, with MRI showing consistently more detailed depiction of extension. Our results indicate that MRI has an important role as a complementary technique in the diagnosis of DVT during pregnancy.

Optimizing imaging in suspected appendicitis (OPTIMAP-study): a multicenter diagnostic accuracy study of MRI in patients with suspected acute appendicitis. Study Protocol

Background

In patients with clinically suspected appendicitis, imaging is needed to substantiate the clinical diagnosis. Imaging accuracy of ultrasonography (US) is suboptimal, while the most accurate technique (CT) is associated with cancer related deaths through exposure to ionizing radiation. MRI is a potential replacement, without associated ionizing radiation and no need for contrast medium administration. If MRI is proven to be sufficiently accurate, it could be introduced in the diagnostic pathway of patients with suspected appendicitis, increasing diagnostic accuracy and improving clinical outcomes, without the risk of radiation induced cancer or iodinated contrast medium-related drawbacks. The multicenter OPTIMAP study was designed to estimate the diagnostic accuracy of MRI in patients with suspected acute appendicitis in the general population.

Methods/Design

Eligible for this study are consecutive patients presenting with clinically suspected appendicitis at the emergency department in six centers. All patients will undergo imaging according to the Dutch guideline for acute appendicitis: initial ultrasonography in all and subsequent CT whenever US does not confirm acute appendicitis. Then MRI is performed in all patients, but the results are not used for patient management. A final diagnosis assigned by an expert panel, based on all available information including 3-months follow-up, except MRI findings, is used as the reference standard in estimating accuracy. We will calculate the sensitivity, specificity, predictive values and inter-observer agreement of MRI, and aim to include 230 patients. Patient acceptance and total imaging costs will also be evaluated.

Discussion

If MRI is found to be sufficiently accurate, it could replace CT in some or all patients. This will limit or obviate the ionizing radiation exposure associated risk of cancer induction and contrast medium induced nephropathy with CT, preventing the burden and the direct and indirect costs associated with treatment. Based on the high intrinsic contrast resolution of MRI, one might envision higher accuracy rates for MRI than for CT. If so, MRI could further decrease the number of unnecessary appendectomies and the number of missed appendicitis cases.

Trial registration

NTR2148

Unenhanced MR Imaging in adults with clinically suspected acute appendicitis

PURPOSE

The purpose of the study was to evaluate unenhanced Magnetic Resonance Imaging (MRI) for the diagnosis of appendicitis or another surgery-requiring condition in an adult population scheduled for emergency appendectomy based on a clinical diagnosis of suspected acute appendicitis.

MATERIALS AND METHODS

The prospective study included 48 consecutive patients (29 female, 19 male, 18-70 years old, mean age=37.1 years). MRI examination was designed to be comfortable and fast; no contrast was administered. The sequences were performed during quiet respiration. The MRI findings were reviewed by two radiologists and one surgeon independent of each other and compared with surgical and pathological records.

RESULTS

According to the surgical and histopathological findings 30 of 48 patients (63%) had acute appendicitis. Of the remaining 18 patients, 4 patients had no reasons for the clinical symptoms and 14 patients had other pathology. For the three reviewers the performance of MRI in the diagnosis of acute appendicitis showed the following sensitivity, specificity and accuracy ranges: 83-93%, 50-83% and 77-83%. Moderate (κ=0.51) and fair (κ=0.31) interobserver agreements in the MR diagnosis of acute appendicitis were found between the reviewers. Sensitivity, specificity and accuracy values for overall performance of MRI in detecting pelvic abnormalities were 100%, 75% (3 of 4 healthy patients were identified by MRI) and 98%, respectively.

CONCLUSION

Unenhanced fast MRI is feasible as an additional fast screening before the appendectomy. It may prevent unnecessary surgeries. The fast MRI examination can be adequately performed on an MRI unit of broad range of field strengths.