Pulmonary circulation imaging: embryology and normal anatomy.

This review focuses on the embryology and normal imaging anatomy of the pulmonary circulation, with emphasis on the major arterial and venous vasculature. The pulmonary circulation and parenchyma have a complex intertwined embryologic origin. Understanding the embryologic basis of normal pulmonary vasculature aids recognition of anomalies and visceral situs in the chest. Adaptive changes to congenital anomalies of the pulmonary arterial vasculature are used to contrast from normal and review associated temporal adaptive vascular and parenchymal changes.

Anomalous pulmonary venous connections.

Developmental lung anomalies are classified into 3 main categories: bronchopulmonary (lung bud) anomalies, vascular anomalies, and combined lung and vascular anomalies. These anomalies are uncommon, and patients are at times asymptomatic; hence, identifying a developmental lung anomaly in the adult can be a challenge. Pulmonary vascular anomalies include interruption or absence of the main pulmonary artery, anomalous origin of the left pulmonary artery from the right pulmonary artery, anomalous pulmonary venous drainage (partial or complete), and pulmonary arteriovenous malformations. Systemic vascular anomalies comprise persistent left superior vena cava, anomalies of azygos and hemiazygos systems, and anomalies of the thoracic aorta and its major branches. In this article, we present embryology, classification, epidemiology, clinical presentation, and imaging features of anomalous pulmonary venous connections, with special emphasis on multidetector computed tomography and magnetic resonance imaging. These state-of-art imaging techniques have facilitated accurate and prompt diagnosis of these anomalies.

The Bin3 RNA methyltransferase targets 7SK RNA to control transcription and translation.

Bicoid-interacting protein 3 (Bin3) is a conserved RNA methyltransferase found in eukaryotes ranging from fission yeast to humans. It was originally discovered as a Bicoid (Bcd)-interacting protein in Drosophila, where it is required for anterior-posterior and dorso-ventral axis determination in the early embryo. The mammalian ortholog of Bin3 (BCDIN3), also known as methyl phosphate capping enzyme (MePCE), plays a key role in repressing transcription. In transcription, MePCE binds the non-coding 7SK RNA, which forms a scaffold for an RNA-protein complex that inhibits positive-acting transcription elongation factor b, an RNA polymerase II elongation factor. MePCE uses S-adenosyl methionine to transfer a methyl group onto the γ-phosphate of the 5' guanosine of 7SK RNA generating an unusual cap structure that protects 7SK RNA from degradation. Bin3/MePCE also has a role in translation regulation. Initial studies in Drosophila indicate that Bin3 targets 7SK RNA and stabilizes a distinct RNA-protein complex that assembles on the 3'-untranslated region of caudal mRNAs to prevent translation initiation. Much remains to be learned about Bin3/MeCPE function, including how it recognizes 7SK RNA, what other RNA substrates it might target, and how widespread a role it plays in gene regulation and embryonic development.

Imaging of the aorta: embryology and anatomy.

This review focuses on the embryology and anatomy of the aorta with some imaging examples. Dividing the aorta by segments of unique function and embryogenesis facilitates organizing the group of potential anomalies encountered. A basic understanding of the embryologic development of the aorta and its major branches helps in understanding and recognizing typical and atypical anatomic findings. Diagnostic imaging of the aorta and its major branches can be accomplished by invasive and noninvasive methods, based on the clinical scenario and the age of the patient. In this review, computed tomography and magnetic resonance imaging examples are emphasized.

Uncommon and unusual gastrointestinal causes of the acute abdomen: computed tomographic diagnosis.

There is a wide variety of uncommon and unusual gastrointestinal causes of acute abdominal and pelvic pain that may be prospectively diagnosed on computed tomography. We demonstrate 10 such diagnoses and briefly review the current computed tomography and clinical literature on intussusception occurring beyond early childhood, small bowel obstruction from internal hernia, cecal volvulus, intramural small bowel hemorrhage, Boerhaave's syndrome, gastrointestinal luminal foreign bodies, small bowel diverticulitis, hemoperitoneum secondary to abdominal tumor; gallstone ileus, and gallbladder torsion. Radiologists and clinicians need to be aware of these disorders, particularly with the widespread utilization of computed tomography (CT) in the management of patients with acute abdominal pain.

Nontraumatic acute abdominal pain: unenhanced helical CT compared with three-view acute abdominal series.

PURPOSE: To prospectively evaluate and compare the diagnostic accuracy of unenhanced helical computed tomography (CT) for patients with nontraumatic acute abdominal pain with that of traditional abdominal radiography. MATERIALS AND METHODS: Institutional review board approval and informed consent were obtained; this study was completed before implementation of the HIPAA. Ninety-one patients (44 men; 47 women; age range, 18-84 years; mean age, 48.5 years) with acute nontraumatic abdominal pain over a 7-month period were referred by the emergency department of one institution. These patients underwent a three-view acute abdominal series (AAS) and unenhanced helical CT. AAS included an upright chest radiograph and upright and supine abdominal radiographs. Unenhanced helical CT images with 5-mm collimation were obtained from the lung bases to the pubic symphysis, without intravenous, oral, or rectal contrast material. AAS and unenhanced helical CT images were each separately and prospectively interpreted by a different experienced radiologist who was blinded to patient history and the images and interpretation of the other examination for each patient. Final diagnosis was established with surgical, pathologic, and clinical follow-up. The sensitivity, specificity, accuracy, positive predictive value, negative predictive value, and positive and negative likelihood ratios were calculated for AAS and unenhanced helical CT. Confidence intervals of 95% were calculated for each value with the standard equation for population proportions. Results of AAS and unenhanced helical CT examinations were compared with chi2 analysis. RESULTS: Among the 91 patients examined, unenhanced helical CT yielded an overall sensitivity, specificity, and accuracy of 96.0%, 95.1%, and 95.6%, respectively. The AAS interpretations yielded an overall sensitivity, specificity, and accuracy of 30.0%, 87.8%, and 56.0%, respectively. The accuracy of unenhanced helical CT was significantly greater than the accuracy of AAS (P < .05). CONCLUSION: AAS is an insensitive technique in the evaluation of nontraumatic acute abdominal pain in adults. Unenhanced helical CT is an accurate technique in the evaluation of adult patients with nontraumatic acute abdominal pain and should be considered as an alternative to radiography as the initial imaging modality.

Utility of magnetic resonance imaging in cardiac venous anatomic variants.

The incidence of persistent left superior vena cava (PLSVC) is approximately 0.5% in the general population; however, the coexistent absence of the right SVC has a reported incidence in tertiary centers of 0.1%. The vast majority of reports are limited to pediatric cardiology. Likewise, sinus of Valsalva aneurysm is a rare congenital anomaly, with a reported incidence of 0.1-3.5% of all congenital heart defects. We present a 71-year-old patient undergoing preoperative evaluation for incidental finding of aortic root aneurysm, and found to have all three in coexistence. Suggestive findings were demonstrated on cardiac catheterization and definitive diagnosis was made by magnetic resonance imaging. The use of MRI for the diagnosis of asymptomatic adult congenital heart disease will be reviewed.

Unenhanced helical CT scanning of the abdomen and pelvis changes disposition of patients presenting to the emergency department with possible acute appendicitis.

This study sought to determine if obtaining an unenhanced abdominopelvic computed tomography (UHCT) scan alters the disposition of patients presenting to the Emergency Department (ED) with signs and symptoms of acute appendicitis. A convenience sample of 101 patients presenting with a clinical picture suggestive of appendicitis were prospectively enrolled. Emergency physicians (EPs) and general surgeons independently recorded their anticipated disposition of each patient as: discharge, admit for observation, or admit for appendectomy. A UHCT scan was then obtained and the patient's ultimate disposition recorded. EPs altered their dispositions after UHCT scanning in 35 patients (34.7%, 95% CI 25.4% to 44.0%), and general surgeons altered their dispositions in 27 patients (26.7%, 95% CI 18.1% to 35.3%). More patients underwent operative intervention than were originally selected by EPs [14 additional patients, (13.9%, 95% CI 7.1% to 20.6%)] or by surgeons [20 additional patients, (19.8%, 95% CI 12.0% to 27.6%)]. CT scan revealed alternative diagnoses in 20 patients (19.8%). UHCT scanning significantly alters patient disposition, and significantly increases the number of operative interventions performed in patients with suspected appendicitis. UHCT scanning may also identify alternate pathology that clinically mimics appendicitis.

Utility of hematuria testing in patients with suspected renal colic: correlation with unenhanced helical CT results.

OBJECTIVES: To determine the utility of hematuria testing in a large series of patients with suspected renal colic using unenhanced helical computed tomography (CT) as the reference standard. METHODS: A retrospective review of the CT reports of all patients who underwent unenhanced helical CT for suspected renal colic at one institution during a 3.5-year period and who also underwent a formal microscopic urinalysis within 24 hours of the CT study was conducted. The sensitivity, specificity, positive predictive value, and negative predictive value of the presence of any blood on the urinalysis for renal colic were calculated. RESULTS: Urolithiasis was present in 587 (62%) of the 950 patients, and 363 patients had negative examinations for renal colic, including 69 with significant alternative diagnoses in the latter group. Of the urinalyses, 492 were true-positive, 174 were true-negative, 189 were false-positive, and 95 were false-negative, yielding a sensitivity, specificity, positive predictive value, and negative predictive value of 84%, 48%, 72%, and 65%, respectively. Forty-six percent of the urinalysis results were negative for blood in the subset of patients with significant alternative diagnoses. CONCLUSIONS: The sensitivity of hematuria on microscopic urinalysis for renal colic using unenhanced CT as the reference standard was 84%, and the specificity and negative predictive value was low. The presence or absence of blood on urinalysis cannot be used to reliably determine which patients actually have ureteral stones.

Comparison of knee magnetic resonance imaging findings in patients referred by orthopaedic surgeons versus nonorthopaedic practitioners.

PURPOSE: To compare the percentages of normal magnetic resonance imaging (MRI) examination results and clinically significant knee abnormalities in patients referred for MRI of the knee by orthopaedic surgery residents and staff with those of patients referred by nonorthopaedic practitioners. TYPE OF STUDY: Retrospective review of MRI findings. METHODS: MRI reports of 754 patients (454 men and 300 women) were retrospectively reviewed; 373 patients were referred from the Department of Orthopaedic Surgery and 381 patients were referred from nonorthopaedic practitioners. The number of normal examination results, meniscal and ligament tears, chondral abnormalities, and Baker's cysts was tabulated and analyzed using a X-square injury analysis. RESULTS: The rate of normal results for nonorthopaedic practitioners was 33.9% (129 of 381) compared with 15.3% (57 of 373) for orthopaedic surgeons (P <.001). Nonorthopaedic surgeons referred 69.4% (129 of 186) of the patients who had normal examination results. The positive finding for a lateral meniscus tear was 29.2% (109 of 373) for orthopaedic surgeons compared with 19.1% (73 of 381) for nonorthopaedic practitioners, which was statistically significant (P =.002) in regard to the distribution of injuries. No difference was found in other abnormalities assessed. CONCLUSIONS: Patients referred by nonorthopaedic practitioners had significantly more normal knee MRI examination results than did those referred by orthopaedic surgeons.

Using contrast-enhanced helical CT to visualize arterial extravasation after blunt abdominal trauma: incidence and organ distribution.

OBJECTIVE: We evaluated the incidence and organ distribution of arterial extravasation identified using contrast-enhanced helical CT in patients who had sustained abdominal visceral injuries and pelvic fractures after blunt trauma. SUBJECTS AND METHODS: Five hundred sixty-five consecutive patients from four level I trauma centers who had CT scans showing abdominal visceral injuries or pelvic fractures were included in this series. The presence or absence of arterial extravasation, as well as the anatomic sites of arterial extravasation, was noted. We obtained clinical follow-up data, including surgical or angiographic findings. RESULTS: In our series, 104 (18.4%) of 565 patients had arterial extravasation. Of the 104 patients, 81 (77.9%) underwent surgery, embolization, or both. The combined rate of surgery or embolization in patients with arterial extravasation was statistically higher than expected at all four institutions (p <0.001). The spleen was the most common organ injured, occurring in 277 (49.0%) of 565 patients, and arterial extravasation occurred in 49 (17.7%) of 277 patients with splenic injury. Several other visceral injuries were associated with arterial extravasation, including hepatic, renal, adrenal, and mesenteric injuries. CONCLUSION: Based on the limited reports of arterial extravasation in the nonhelical CT literature, the percentage (18%) of clinically stable patients in our study with CT scans showing arterial extravasation was higher than anticipated. This finding likely reflects the improved diagnostic capability of helical CT. Although the spleen and liver were the organs most commonly associated with arterial extravasation, radiologists should be aware that arterial extravasation may be associated with several other visceral injuries.

The "flat cava" sign revisited: what is its significance in patients without trauma?

OBJECTIVE: The purpose of this study was to evaluate the clinical significance of the "flat cava" sign on abdominal CT scans in hospitalized patients without trauma. MATERIALS AND METHODS: CT scans of the abdomen of 500 inpatients imaged for a wide variety of nontraumatic indications were retrospectively reviewed for a flat cava sign. Two radiologists measured the maximal anteroposterior and transverse diameters of the inferior vena cava at four predetermined levels. The medical records of the subset of patients with a flat cava sign--defined as a maximal transverse-to-anteroposterior ratio of 3:1 or greater at one or more of the four levels--were reviewed for evidence of hypovolemia or hypotension. RESULTS: Seventy patients (14%; 48 women, 22 men) had a flat inferior vena cava present on at least one of the four levels. Of these 70 patients, 21 had definite and three had possible clinical evidence of hypotension or hypovolemia. A flat cava sign isolated to only one level was seen in 22 of the 70 patients, most commonly at the level just below the renal veins, and only four of these 22 patients had evidence of hypotension or hypovolemia. CONCLUSION: Of the 500 inpatients, 14% had a flat cava sign on at least one of the four levels examined on abdominal CT scans. The majority of these patients with a flat cava sign did not have hypotension or evidence of hypovolemia, but a minority (30%) did.