MRI in pregnancy: Indications and practical considerations.

There is a constantly evolving knowledgebase regarding the safety of MRI in pregnant patients, as well as the safety of gadolinium administration, given potential fetal risks. This review provides an overview of national and international recommendations for patient screening and safety by trimester, evaluates the most recent literature regarding administration of gadolinium in pregnant patients, and discusses technical requirements when imaging pregnant patients. A protocol for imaging pregnant patients is provided, and multiple common indications for MRI in pregnancy are discussed. Level of Evidence 5. Technical Efficacy Stage 5. J. Magn. Reson. Imaging 2019;49:621-631.

Cardiovascular MRI in Detection and Measurement of Aortic Atheroma in Stroke/TIA patients.

BACKGROUND: Aortic Atheroma (AoA) is an independent risk factor for new and recurrent stroke. AoA ulceration and mobility are associated with an increased risk for brain embolism. Transesophageal echocardiography (TEE) is the gold standard for detection and measurement of AoA in stroke/TIA patients. Cardiovascular MRI (cMRI) could be an alternative, non-invasive imaging modality for stroke/TIA patients. The objective of this study was to assess the accuracy and correlation of AoA detected and measured by cMRI versus TEE in patients with recent stroke/TIA. METHODS AND RESULTS: Twenty-two stroke/TIA patients undergoing TEE as a part of their stroke workup consented to a protocol-mandated cMRI performed on a 1.5 T magnet. The protocol included an axial non-breathhold EKG-gated dual-echo spin echo MRI of the thoracic aorta (TR/TE1/TE2=900/29/69) and a contrast-enhanced breathhold 3D gradient-echo image of the thorax (flip/TR/TE=12/4.0/1.71). Maximum plaque thickness, ulceration (≥ 2 mm) and mobility of AoA were assessed in the proximal (ascending and proximal arch) and distal (distal arch and descending) segments of thoracic aorta by a cardiologist to interpret the TEE and a radiologist to interpret the cMRI. There was good correlation between cMRI and TEE in measurement of plaque thickness in the proximal segments (R=0.73, p<0.0001) and the distal segments (R=0.81, p<0.0001) of the aortic arch (AA). cMRI had a high degree of accuracy in detecting measurable AoA (≥ 1 mm) in the proximal segments (sensitivity 90%, specificity 100%), as well as the distal segments (sensitivity 67%, specificity 100%). cMRI also had a high degree of accuracy in detecting significant AoA (≥ 4 mm) in proximal segments (sensitivity 71%, specificity 93%), as well as distal segments (sensitivity 71%, specificity 100%). CONCLUSION: The study showed a high degree of accuracy and correlation of AoA detected and measured by cMRI as compared to TEE in patients with recent stroke/TIA. This technique has limitations in detection of AoA ulceration, and protocols assessing AoA mobility need to be developed.

Image-guided optimization of the ECG trace in cardiac MRI.

Improper electrocardiogram (ECG) lead placement resulting in suboptimal gating may lead to reduced image quality in cardiac magnetic resonance imaging (CMR). A patientspecific systematic technique for rapid optimization of lead placement may improve CMR image quality. A rapid 3 dimensional image of the thorax was used to guide the realignment of ECG leads relative to the cardiac axis of the patient in forty consecutive adult patients. Using our novel approach and consensus reading of pre- and post-correction ECG traces, seventy-three percent of patients had a qualitative improvement in their ECG tracings, and no patient had a decrease in quality of their ECG tracing following the correction technique. Statistically significant improvement was observed independent of gender, body mass index, and cardiac rhythm. This technique provides an efficient option to improve the quality of the ECG tracing in patients who have a poor quality ECG with standard techniques.

Overlap syndrome of autoimmune chronic liver diseases: MRI findings.

PURPOSE: To describe the MR findings of overlap syndromes of autoimmune chronic liver diseases. METHODS: Review of clinical and radiological databases between March 2001 and July 2008 for patients with a clinical diagnosis and liver biopsy features compatible with overlap syndrome who had also undergone an abdominal MRI yielded 15 adult patients. MR features of overlap syndrome were reviewed by two radiologists by consensus. Two radiologists independently reviewed the studies in a blinded fashion for primary sclerosing cholangitis (PSC)-type or non-PSC-type features to assess interobserver agreement. RESULTS: PSC-type and non-PSC-type overlap syndrome had distinctive MR features. In the consensus review, all 12 patients with PSC-type overlap syndrome were correctly identified. Imaging findings included central macroregeneration (N = 9), peripheral atrophy (N = 7), biliary duct beading (N = 12), biliary dilation (N = 10), or a combination of all four findings (N = 7). The presence of any of the first three features had 100% specificity for a PSC-type overlap syndrome. Patients with non-PSC-type overlap (N = 3) showed relatively normal liver morphology (N = 3) and minimal biliary ductal dilatation in one patient. There was good interobserver agreement (kappa = 0.76). CONCLUSION: Patients with serologic or pathologic evidence of AIH or PBC with imaging features of PSC may have PSC-type overlap syndrome.

Helical computed tomography inaccuracy in the detection of pulmonary metastases: can it be improved?

BACKGROUND: In thoracic surgery, manual lung palpation for detection of pulmonary metastases during resection is the standard of care, despite improvements in computed tomography (CT) imaging. In our previous study based on chart review alone, the accuracy of helical CT in the detection of pulmonary metastases was surprisingly low, with a sensitivity of 78%. We hypothesized that this may be improved by scan interpretation with adequate clinical history and focused documentation of all pulmonary lesions, and may be influenced by the training of the reader. METHODS: Preoperative CT scans of 53 patients undergoing 60 cases of pulmonary metastasectomy at our center from 1996 to 2004 were retrospectively reviewed by a dedicated chest radiologist and a non-chest radiologist. Nodules detected on preoperative helical CT were compared with pathologically confirmed metastases. RESULTS: In 27 of 59 (46%) cases read by radiologist 1, and 27 of 58 (47%) cases read by radiologist 2, metastases found by lung palpation were not seen on preoperative CT. Preoperative CT was entirely correct (no missed metastases or false-positive lesions) in only 11 of 59 (19%) of cases read by radiologist 1, and 11 of 58 (19%) of cases read by radiologist 2. CONCLUSIONS: Helical CT misses metastases in 46% to 47% of cases. Accuracy of preoperative CT scanning for detection of pulmonary metastases was not improved with the provision of clinical history to the reader, nor was it influenced by the interpreter's training. A combined approach to pulmonary metastasectomy including preoperative and postoperative CT as well as manual lung palpation is necessary to render the patient disease-free.

Future directions in body magnetic resonance imaging.

Technologic innovations in instrumentation and contrast agents naturally lead to new clinical and research applications in body MRI. Although long-range predictions of innovation are an uncertain process, short-term trends in development are more readily discernable. This review will provide examples of recent developments in magnetic resonance spectroscopic imaging, contrast agent development and molecular imaging, instrumentation, post-processing, and screening in an attempt to describe areas of active research.

Suspected pancreatic cancer: evaluation by dynamic gadolinium-enhanced 3D gradient-echo MRI.

OBJECTIVE: The objective of our study was to determine the sensitivity and specificity of gadolinium-enhanced 3D gradient-echo (GRE) MR images in the detection of pancreatic cancer. CONCLUSION: Dynamic gadolinium-enhanced 3D GRE images are both sensitive and specific in the detection of pancreatic cancer. Our study shows that the identification of pancreatic cancer using these images can be performed with a high degree of confidence and accuracy, making them very useful in the detection of pancreatic cancer.

MR imaging findings in autoimmune hepatitis: correlation with clinical staging.

PURPOSE: To retrospectively evaluate the morphologic and enhancement features of the liver on magnetic resonance (MR) images obtained in patients with autoimmune hepatitis (AIH) and to determine if there is a correlation between MR imaging findings and severity of clinical disease as measured with the Mayo end-stage liver disease (MELD) score. MATERIALS AND METHODS: This study was compliant with the Health Insurance Portability and Accountability Act and approved by the institutional review board. The need for informed consent was waived. Thirty-two patients (29 female and three male patients; mean age, 44 years; age range, 14-69 years) undergoing treatment for AIH underwent unenhanced and gadolinium-enhanced MR imaging. Two radiologists reviewed all cases independently to determine the presence of patchy or heterogeneous liver enhancement, biliary duct changes, lymphadenopathy, and findings of portal hypertension. Fibrosis was graded as mild, moderate, or severe reticular (corresponding to a grading scale of 1-3) or as confluent. Agreement between radiologists was assessed by using kappa coefficients. Mean MELD scores were compared across fibrosis categories by using the Kruskal-Wallis analysis of variance. RESULTS: Of the 32 patients, two (6%) had no imaging findings of cirrhosis. Thirty patients (94%) had reticular fibrosis with a mean grade of 1.8. Six patients had confluent fibrosis, and all six had associated reticular fibrosis. Mild intrahepatic biliary duct dilatation involving the right and left lobes was observed in four patients (12%). Lymphadenopathy was observed in 12% of patients. None of the patients had hepatocellular carcinoma. There was no significant overall association between fibrosis grade and MELD score (P = .36). CONCLUSION: Although fibrosis is a common feature in AIH and is often moderate to severe, no significant correlation between fibrosis grade and MELD score was found.

Future horizons in MR imaging.

In this article, we defined the major areas of active research in clinical MR imaging. Further increases in the number of parallel coils within an imaging array and in advances in parallel imaging pulse sequences and postprocessing will lead to further reductions in imaging time analogous to the impact of multidetector CT on helical CT. The synergism between parallel and high-field imaging will aid the development of high-field imaging. The combined dynamic and hepatic parenchymal enhancement of new contrast agents that have or may soon receive FDA approval will enable improved detection and characterization of liver lesions. The lymphotropic SPIO agents will remain an active area of clinical research to further assess their role in oncologic staging. Molecular imaging contrast research using magnetic particles and MR microscopy will continue to flourish. Screening examinations by MR imaging will re-main an area of research for the short- and intermediate term, with the final outcome dependent more on socioeconomic costs than the underlying capability of achieving high-quality screening studies.

MRI findings of primary small-cell carcinoma of kidney.

We report the MRI findings of primary small-cell carcinoma of the kidney (PSCCK) in a 59-year-old female. This tumor appeared as a 16-cm mass that arose from the right kidney. This lesion had diminished signal on T1-weighted images and heterogeneous mixed signal on T2-weighted images. The tumor primarily involved the renal medulla with persistent thin renal cortex. Despite the tumors' large size, no substantial central necrosis was present. The predominant medullary location and the lack of central necrosis in this large tumor were features unusual for renal cell carcinoma and should raise the suspicion of another malignancy, the differential diagnosis of which should contain extrapulmonary small-cell carcinoma of the kidney.

MRI of acute abdominal and pelvic pain in pregnant patients.

OBJECTIVE: The purpose of this study was to show the usefulness of MRI in the evaluation of pregnant women with acute abdominal or pelvic pain. SUBJECTS AND METHODS: All MRI studies of pregnant patients who were referred for examination because of acute abdominal or pelvic pain between June 2002 and May 2004 were included in this study (n=29). The use of MRI was at the discretion of the clinician. Fetal sonography was performed in all patients before any other imaging. A complete abdominal sonographic examination was performed in six patients before MRI. In the remaining 23 patients, MRI was the choice for primary imaging. Multiplanar multisequence MR images of the abdomen and pelvis were obtained in each patient. Unenhanced images were reviewed by an experienced radiologist to determine whether a diagnosis could be made without the administration of gadolinium. In 22 of 29 studies, gadolinium was not administered. The prospective clinical MR interpretations were compared with follow-up medical, surgical, and obstetric records to determine the correctness of the interpretation. All patients were followed up until the date of article submission or until the date of final chart entry. RESULTS: Correlation of prospective clinical MR interpretations with follow-up medical records showed correct identification of disease entities in all but one patient. In one patient, torsion of the ovary was neither described prospectively nor seen in retrospect. The following disease processes were correctly identified using MRI: appendiceal abscess (n=1), appendicitis (n=2), intraabdominal and rectus muscle abscess (n=1), intussusception (n=1), pancreatitis (n=1), ulcerative colitis (n=1), Crohn's disease with diffuse peritoneal inflammation (n=1), bilateral adrenal hemorrhage (n=1), pyelonephritis (n=2), hydronephrosis (n=1), uterine fibroid degeneration (n=2), degeneration and torsion of a submucosal uterine fibroid (n=1), simple ovarian cysts (n=1), and ovarian torsion (n=1). Twelve of the 29 patients had normal findings on MR examinations and unremarkable follow-up. CONCLUSION: The intrinsic safety of MRI and its ability to accurately show abdominal and pelvic disease in pregnant patients make it highly useful in the evaluation of these patients.

Immunoblastic large B-cell lymphoma of the peripancreatic head region: MR findings.

We report the magnetic resonance (MR) appearance of a large B-cell lymphoma in the peripancreatic head region, in a 38-year-old male who presented with a 1-month history of pruritus and jaundice. Routine laboratory examination at presentation revealed an elevated bilirubin. The tumor was a large, solitary well-defined mass with no evidence of necrosis, which showed mild diffuse heterogeneous enhancement. The tumor was closely applied to the lateral margin of the head of the pancreas. The constellation of MR findings was interpreted as consistent with the correct eventual diagnosis of lymphoma.