Musculoskeletal pitfalls and pseudotumours in the pelvis: a pictorial review for body imagers.

Many musculoskeletal abnormalities in the pelvis are first seen by body imagers while reviewing pelvic cross-sectional studies, and some of these abnormalities may mimic malignancy or another aggressive process. This article describes nine musculoskeletal pseudotumours and interpretative pitfalls that may be seen on CT, MRI and ultrasound imaging of the pelvis. Awareness of these pitfalls and pseudotumours may help avoid misdiagnosis and prevent inappropriate intervention or management.

Imaging malignant and apparent malignant transformation of benign gynaecological disease.

Common benign gynaecological diseases, such as leiomyoma, adenomyosis, endometriosis, and mature teratoma, rarely undergo malignant transformation. Benign transformations that may mimic malignancy include benign metastasizing leiomyoma, massive ovarian oedema, decidualization of endometrioma, and rupture of mature teratoma. The aim of this review is to provide a contemporary overview of imaging findings in malignant and apparent malignant transformation of benign gynaecological disease.

Diagnostic evaluation of cystic pancreatic lesions.

BACKGROUND: Cystic pancreatic neoplasms (CPNs) present a unique challenge in preoperative diagnosis. We investigated the accuracy of diagnostic methods for CPN. MATERIAL AND METHODS: This retrospective cases series includes 70 patients who underwent surgery at a university hospital for presumed CPNs between 1997 and 2003, and for whom a definitive diagnosis was established. Variables examined included symptoms, preoperative work-up (including endoscopic retrograde cholangiopancreatography (ERCP) in 22 cases and endoscopic ultrasound (EUS) in 12), and operative and pathological findings. Preoperative computed tomography (CT) and magnetic resonance imaging (MRI) scans (n=50 patients; CT=48; MRI=13) were independently reviewed by two blinded GI radiologists. RESULTS: The final histopathologic diagnoses were mucinous cystic neoplasm (n=13), mucinous cystadenocarcinoma (10), serous cystadenoma (11), IPMN (14), simple cyst (3), cystic neuroendocrine tumor (5), pseudocyst (4), and other (10). Overall, 25 of 70 were malignant (37%), 21 premalignant (30%), and 24 benign (34%). The attending surgeon's preoperative diagnosis was correct in 31% of cases, incorrect in 29%, non-specific "cystic tumor" in 27%, and "pseudocyst vs. neoplasm" in 11%. Eight had been previously managed as pseudocysts, and 3 pseudocysts were excised as presumed CPN. In review of the CT and MRI, a multivariate analysis of the morphologic features did not identify predictors of specific pathologic diagnoses. Both radiologists were accurate with their preferred (no. 1) diagnosis in <50% of cases. MRI demonstrated no additional utility beyond CT. CONCLUSIONS: The diagnosis of CPN remains challenging. Cross-sectional imaging methods do not reliably give an accurate preoperative diagnosis. Surgeons should continue to err on the side of resection.

3D MR spectroscopic imaging in the evaluation of prostate cancer.

The management of prostate cancer is a complex issue with a varying range of treatment options available. Magnetic resonance (MR) imaging of the prostate has been available for sometime but has the limitation of only anatomical evaluation. Three-dimensional MR spectroscopy is emerging as a new and sensitive tool in the metabolic evaluation of prostate cancer. This article reviews the principle, techniques, and methods of evaluation of spectroscopy and also discusses the applications of spectroscopy in the current management of prostate cancer.

Case report: Renal replacement lipomatosis associated with renal transplantation.

We report a case of extensive renal replacement lipomatosis demonstrated by ultrasound (US) and computed tomography (CT) in a 57-year-old woman with a history of two cadaveric renal transplants. One transplant was non-functional due to chronic rejection. The second renal transplant is functioning normally and the renal replacement lipomatosis did not cause mass effect on either of the renal transplants.

Pyelonephritis mimicking colitis on CT: case report.

We report a patient with acute pyelonephritis in whom the dominant computed tomographic findings were ascending colon and cecal wall thickening and pericolonic fat stranding, likely related to contiguous inflammation from the right kidney. To our knowledge, this is the first report of acute pyelonephritis affecting the right colon mimicking colitis on computed tomography.

Peritoneal coccidioidomycosis: a potential CT mimic of peritoneal malignancy.

Peritoneal involvement is a rare extrapulmonary manifestation of coccidioidomycosis. We report a patient with meningeal coccidioidomycosis who was found to have multiple, globular, peripherally enhancing deposits in the peritoneal cavity at abdominal computed tomography, raising the consideration of peritoneal malignancy. Aspiration biopsy demonstrated peritoneal coccidioidomycosis. The particular computed tomographic findings of peritoneal coccidioidomycosis seen in this patient have not been previously described.

Evaluation of femur length during the second and third trimesters in fetuses with myelomeningocele.

OBJECTIVES: To determine if the femur length of fetuses with myelomeningocele is shorter in the second and third trimesters compared with that of normal fetuses. METHODS: We retrospectively collected measurements of femur length, head circumference, biparietal diameter and abdominal circumference from detailed obstetric ultrasound studies performed during the second and third trimesters in 31 fetuses with myelomeningocele and 43 fetuses with no detectable anomaly. The gestational age predicted by each parameter (based on Hadlock's tables) was compared with the true gestational age (based on last menstrual period), using the ANCOVA test to determine if there was a statistically significant difference between the two groups of fetuses. RESULTS: There was no significant difference in femur length (P = 0.60) or in abdominal circumference (P = 0.85) between fetuses with myelomeningocele and normal fetuses. Fetuses with myelomeningocele did have a significantly lower biparietal diameter and head circumference (P < or = 0.001). CONCLUSIONS: Myelomeningocele is not associated with reduced femur length in the second and third trimesters, suggesting that the known postnatal lower extremity foreshortening in patients with myelomeningocele develops late in gestation or after birth.

Renal involvement by Rosai-Dorfman disease: CT findings.

Rosai-Dorfman disease is a rare disease characterized histologically by proliferation of histiocytes and has clinical features suggestive of a lymphomalike disease. Lymph nodes and extranodal sites might be involved, but renal involvement is rare. We present computed tomographic findings in three cases of renal involvement by Rosai-Dorfman disease. Two cases showed renal hilar masses and one case showed subcapsular hypodense infiltration. Renal involvement by Rosai-Dorfman disease has a characteristic appearance and should be included in the differential diagnosis of renal hilar masses or subcapsular hypodense infiltration.

Imaging of hepatocellular carcinoma: a practical approach.

Imaging of hepatocellular carcinoma (HCC) is complicated because the tumor has a varied radiologic appearance and frequently coexists with cirrhotic regenerative and dysplastic nodules. In cirrhotic patients, any dominant solid nodule that is not clearly a hemangioma should be considered a HCC until proven otherwise, especially if the lesion is hypervascular, of high T2 signal intensity, or demonstrates venous invasion. Biopsy of HCC in cirrhosis is risky and surveillance is often preferable. The doubling time of HCC is 1 to 12 months, and a nodule that is stable over 4 months is very unlikely to be a HCC. However, stable nodules cannot be dismissed, since livers containing dysplastic nodules are at high risk to develop HCC. In noncirrhotic patients, any solid mass that is not clearly a hemangioma or focal nodular hyperplasia is potentially a HCC, and biopsy may be required. Venous invasion by tumor should be distinguished from bland thrombus. Imaging detection of nodal metastases is limited by the frequent finding of benign reactive lymphadenopathy in cirrhosis. Resection is the preferred treatment for HCC, but is contraindicated in the presence of tumors in both lobes, major venous invasion, invasion of adjacent organs other than the gallbladder, tumor rupture, nodal metastases, or distant metastases.

Congenital diaphragmatic hernia: prenatal evaluation with MR lung volumetry--preliminary experience.

PURPOSE: To determine the interobserver variability of prenatal magnetic resonance (MR) lung volumetry and to assess the value of MR lung volumetric findings as predictors of outcome in fetuses with congenital diaphragmatic hernia. MATERIALS AND METHODS: Prenatal MR imaging was performed in 26 fetuses with unilateral congenital diaphragmatic hernia. Two independent observers performed planimetric measurement of lung volume. Relative lung volume was calculated as the observed total lung volume expressed as a percentage of the total lung volume predicted from fetal size. Relative lung volume was correlated with the ultrasonographic lung-head ratio in left-sided congenital diaphragmatic hernias evaluated before 27 weeks gestation (n = 21) and with pregnancy outcome in all cases of isolated left-sided congenital diaphragmatic hernia without prenatal intervention (n = 11). RESULTS: Observers demonstrated excellent agreement in total lung volume measurements at MR imaging, with an intraclass correlation coefficient of 0.95. Relative lung volume was positively correlated with lung-head ratio (r = 0.78, P <.001). By using rank order analysis in the pregnancy outcome group, relative lung volume was predictive of prognosis (P <.05) when adjusted for gestational age at delivery and birth weight. Three of four fetuses with a relative lung volume of less than 40% died. CONCLUSION: Interobserver agreement is high at MR lung volumetry, and its findings are predictive of outcome in fetuses with isolated left-sided congenital diaphragmatic hernia.

MRI of vaginal leiomyomas.

The MR appearances of two cases of vaginal leiomyoma are described. Both patients presented with a periurethral mass; one patient presented during pregnancy. MRI allowed precise anatomic localization of the masses and confident preoperative characterization in both cases.

Brachytherapy for prostate cancer: endorectal MR imaging of local treatment-related changes.

PURPOSE: To determine the local treatment-related endorectal magnetic resonance (MR) imaging findings after brachytherapy for prostate cancer. MATERIALS AND METHODS: Endorectal MR imaging was performed in 35 consecutive patients at a mean interval of 12 months (range, 1-31 months) after brachytherapy for prostate cancer. Transverse T1-weighted and high-spatial-resolution transverse and coronal T2-weighted images were acquired. Two readers reviewed MR image quality and findings, with discrepancies resolved by consensus. Posttreatment urinary symptoms in patients (n = 24) were documented by using chart review. RESULTS: All studies were of diagnostic quality. On T2-weighted images, prostatic findings consisted of diffuse low signal intensity (n = 35) and indistinct zonal anatomy (n = 34). Intra- and extraprostatic seed locations could be distinguished. The most common extraprostatic site of seed implantation was the neurovascular bundles (n = 35, bilateral in 32). The most common extraprostatic tissue finding was increased signal intensity on T2-weighted images in the levator ani muscle (n = 34) and the genitourinary diaphragm (n = 28). Postbrachytherapy urinary symptoms showed no demonstrable correlation with periurethral or genitourinary diaphragm seed implantation or with signal intensity change in the genitourinary diaphragm. CONCLUSION: Endorectal MR imaging can be used to evaluate seed distribution and to demonstrate treatment-related changes after brachytherapy for prostate cancer.

Role of magnetic resonance imaging in fetal surgery.

Prenatal magnetic resonance imaging (MRI) has several advantages over obstetric ultrasound, including a larger field of view, superior soft-tissue contrast, more precise volumetric measurements, and greater accuracy in the demonstration of intracranial abnormalities. Prenatal MRI has been shown to positively and incrementally influence management in a substantial proportion of patients being considered for fetal intervention. Despite these findings, precise indications for prenatal MRI in the setting of fetal surgery are not yet established, because both prenatal MRI and fetal surgery are relatively new techniques that remain in evolution. Conditions in which prenatal MRI appears to contribute to fetal surgical planning and postoperative evaluation are described in this review. These conditions include congenital diaphragmatic hernia, cystic adenomatoid malformation, sacrococcygeal teratoma, complicated twin pregnancies, upper airway obstruction, and myelomeningocele.

Association of renal agenesis and mullerian duct anomalies.

PURPOSE: The purpose of this work was to determine the association of renal agenesis with the different types of mullerian duct anomalies (MDAs). METHOD: A 5 year retrospective review of MR records identified 57 patients with MDAs. Associated renal anomalies were correlated with the various types of MDAs. RESULTS: Renal agenesis was found in 17 (29.8%) of 57 patients. No other renal anomalies were identified. Renal agenesis was more frequent in patients with uterus didelphys (13/16 cases). Renal agenesis was also seen in patients with uterine agenesis (2/5 cases) and unicornuate uterus (2/7 cases). All 11 cases of obstructed uterus didelphys were associated with renal agenesis ipsilateral to the side of the obstructing transverse hemivaginal septum. CONCLUSION: Renal agenesis is more commonly seen in uterus didelphys than in other types of MDAs. Renal agenesis in patients with uterus didelphys is often ipsilateral to an obstructing, transverse, hemivaginal septum.

Fast MR imaging of fetal CNS anomalies in utero.

BACKGROUND AND PURPOSE: Although sonography is the primary imaging technique for evaluating the developing fetus, significant limitations exist in the sonographic prenatal diagnosis of many brain disorders. Fast MR imaging is increasingly being used to determine the underlying cause of nonspecific fetal CNS abnormalities detected sonographically and to confirm or provide further support for such anomalies. Our goal was to determine the value of MR imaging in establishing the diagnosis of fetal CNS anomalies, to ascertain how this information might be used for patient counseling, and to assess its impact on pregnancy management. METHODS: We prospectively performed MR examinations of 73 fetuses (66 pregnancies) with suspected CNS abnormalities and compared these with available fetal sonograms, postnatal images, and clinical examinations. Retrospectively, the impact on patient counseling and pregnancy management was analyzed. RESULTS: Images of diagnostic quality were routinely obtained with in utero MR imaging, which was particularly valuable in detecting heterotopia, callosal anomalies, and posterior fossa malformations, and for providing excellent anatomic information. We believe that 24 (46%) of 52 clinical cases were managed differently from the way they would have been on the basis of sonographic findings alone. In every case, the referring physicians thought that MR imaging provided a measure of confidence that was not previously available and that was valuable for counseling patients and for making more informed decisions. CONCLUSION: Sonography is the leading technique for fetal assessment and provides reliable, inexpensive diagnostic images. Fast MR imaging is an important adjunctive tool for prenatal imaging in those instances in which a complex anomaly is suspected by sonography, when fetal surgery is contemplated, or when a definitive diagnosis cannot be determined.

Sextant localization of prostate cancer: comparison of sextant biopsy, magnetic resonance imaging and magnetic resonance spectroscopic imaging with step section histology.

PURPOSE: We compared the accuracy of endorectal magnetic resonance imaging (MRI) and magnetic resonance spectroscopic imaging with that of sextant biopsy for the sextant localization of prostate cancer. MATERIALS AND METHODS: Sextant biopsy, MRI, magnetic resonance spectroscopic imaging and radical prostatectomy with step section histology were done in 47 patients with prostate cancer. For each sextant we categorized biopsy and imaging results as positive or negative for cancer. Step section histology was used as the standard of reference. RESULTS: For sextant localization of prostate cancer MRI and magnetic resonance spectroscopic imaging were more sensitive but less specific than biopsy (67% and 76% versus 50%, and 69% and 68% versus 82%, respectively). The sensitivity of sextant biopsy was significantly less in the prostate apex than in the mid prostate or prostate base (38% versus 52% and 62%, respectively). MRI and magnetic resonance spectroscopic imaging had similar efficacy throughout the prostate compared with biopsy only as well as better sensitivity and specificity in the prostate apex (60% and 75%, and 86% and 68%, respectively). A positive biopsy or imaging result had 94% sensitivity for cancer and concordant positivity by all 3 tests was highly specific at 98%. CONCLUSIONS: Overall MRI and magnetic resonance spectroscopic imaging have accuracy similar to biopsy for intraprostatic localization of cancer and they are more accurate than biopsy in the prostate apex. These 2 imaging modalities may supplement biopsy results by increasing physician confidence when evaluating intraprostatic tumor location, which may be important for planning disease targeted therapy.

Normal and hypoplastic fetal lungs: volumetric assessment with prenatal single-shot rapid acquisition with relaxation enhancement MR imaging.

PURPOSE: To determine which parameters are most closely correlated with normal fetal total lung volume and to investigate the use of these parameters in the evaluation of fetal pulmonary hypoplasia. MATERIALS AND METHODS: Single-shot rapid acquisition with relaxation enhancement (RARE) magnetic resonance (MR) imaging was used to perform planimetric measurement of total lung volume in 46 fetuses at 18-32 weeks gestation. Total lung volume was correlated with gestational age, and biometric parameters in fetuses were correlated with normal chest findings at ultrasonography (US) (n = 24). This analysis was used to evaluate relative lung volume in fetuses suspected of having pulmonary hypoplasia (n = 22). RESULTS: Normal fetal total lung volume was strongly correlated with liver volume measured at MR imaging (r = 0.94), fetal weight estimated at US (r = 0.93), head circumference measured at US (r = 0.90), and gestational age (r = 0.87). In fetuses suspected of having pulmonary hypoplasia, the relative lung volume varied from 4.6% to 81.6% when the observed total lung volume was expressed as a percentage of the predicted total lung volume. CONCLUSION: Normal fetal total lung volume is strongly correlated with biometric measurements. Relative fetal lung volume can be calculated by expressing the observed volume as a percentage of the predicted volume calculated from biometric measurements; knowledge of the relative fetal lung volume assists in the confirmation and quantification of fetal pulmonary hypoplasia.