Staging of malignant pleural mesothelioma: comparison of CT and MR imaging

OBJECTIVE: This article compares the accuracy of CT with that of MR imaging in staging of malignant pleural mesothelioma. SUBJECTS AND METHODS: Ninety-five patients were enrolled in a prospective staging protocol based on the International Mesothelioma Interest Group staging system. Sixty-five patients underwent CT and MR imaging and a surgical procedure (excluding percutaneous needle biopsy) to stage and resect the tumor. Receiver operating characteristic analyses were performed. CT and MR scans were interpreted independently by observers who were unaware of the results of the other imaging study; these imaging findings were compared with the results of surgery and pathologic examination. RESULTS: The areas under the receiver operating characteristic curves for eight of 10 features revealed by imaging showed no statistically significant differences between CT and MR imaging. However, MR imaging was superior to CT in revealing invasion of the diaphragm (A(z) = .55 for CT versus .82 for MR imaging) and in revealing invasion of endothoracic fascia or solitary resectable foci of chest wall invasion (A(z) = .46 for CT; A(z) = .69 for MR imaging). Several anatomic regions could not be evaluated because positive findings at surgery were rare. CONCLUSION: CT and MR imaging are of nearly equivalent diagnostic accuracy in staging malignant pleural mesothelioma. MR imaging is superior to CT in revealing solitary foci of chest wall invasion and endothoracic fascia involvement and in showing diaphragmatic muscle invasion; however, this advantage does not affect surgical treatment. For cost reasons, CT should be considered the standard diagnostic study before therapy.     

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.Musculoskeletal abnormalities in the pelvis are often first seen by body imagers. Some of these abnormalities may mimic malignancy or aggressive processes, leading to inappropriate referral and/or intervention. Awareness of these pitfalls may help body imagers avoid misinterpretation and facilitate better patient care. This pictorial essay describes the radiological findings in nine potentially confusing pelvic musculoskeletal processes that body imagers may encounter.     

Advances in oncologic imaging

Imaging has become a pivotal component throughout a patient's encounter with cancer, from initial disease detection and characterization through treatment response assessment and posttreatment follow‐up. Recent progress in imaging technology has presented new opportunities for improving clinical care. This article provides updates on the latest approaches to imaging of 5 common cancers: breast, lung, prostate, and colorectal cancers, and lymphoma. CA Cancer J Clin 2012. © 2012 American Cancer Society.     

Subcutaneous nodules at the injection site of low-molecular-weight heparin: a mimic of metastatic disease at CT

PURPOSE: To describe the appearance and prevalence of subcutaneous nodules in the anterior abdominal wall seen at CT in cancer patients receiving subcutaneous injections of low-molecular-weight heparin (LMWH). METHODS: CT examinations were reviewed in 426 patients receiving subcutaneous abdominal wall injections of LMWH for the presence of nodules. Nodules were evaluated for contour, maximal diameter, CT attenuation, and presence of hazy changes or air in the surrounding fat. RESULTS: Fourteen (3%) of the 426 patients had nodules attributable to subcutaneous injections of LMWH. Findings included poorly defined borders (100%), adjacent hazy soft tissue changes (100%), adjacent air (57%), and a mean CT attenuation of -4.4 HU (range: -50-40 HU). Three (0.7%) of 426 patients had nodules caused by metastatic disease. One (33%) nodule had poorly defined borders, two (67%) had surrounding hazy changes, one (33%) had air in adjacent tissue, and there was a mean CT attenuation of 44 HU (range: 14-140 HU). One (0.2%) patient had a subcutaneous nodule of uncertain etiology. CONCLUSION: Patients receiving subcutaneous injections of LMWH may develop nodules at the injection sites. Such nodules can resemble metastatic tumor deposits at CT, and careful correlation with clinical history and growth trends of metastatic deposits elsewhere in the patient is needed to avoid misdiagnosis.     

MR signal characteristics of cadaveric bone allografts in three children with primary bone tumors treated with limb salvage therapy

Three children with adult cadaveric bone allografts for the treatment of bone malignancies are presented. Follow-up magnetic resonance (MR) imaging demonstrated decreased signal on T1-weighted imaging and increased signal on T2-weighted imaging in the allograft without clinical evidence of recurrent disease. These signal characteristics appear to be a normal finding in cadaveric bone allografts and should not be mistaken for recurrence. The finding may reflect persistent marrow necrosis within the allograft marrow cavity.     

Hepatic lesions deemed too small to characterize at CT: prevalence and importance in women with breast cancer

PURPOSE: To retrospectively evaluate the prevalence and clinical importance of hepatic lesions considered too small to characterize (TSTC) at initial computed tomography (CT) in women with breast cancer. MATERIALS AND METHODS: Approval for this retrospective study was obtained from the institutional review board, which waived the requirement for informed consent. For each woman who received a diagnosis of breast cancer between 1998 and 2002, the authors reviewed the report of the first contrast material-enhanced CT examination that included assessment of the liver. For women with no definite liver metastasis and at least one hepatic lesion considered TSTC, reports of follow-up imaging examinations were reviewed for a change in lesion size; medical records and images were reviewed if there was a change in lesion size. The 95% confidence intervals (CIs) were calculated for best- and worst-case analyses of cases in which different assumptions were used to classify a lesion as benign. RESULTS: Of 7692 women, 1012 (13.2%) underwent contrast-enhanced CT including liver assessment. The mean age of the 1012 women was 54.6 years (range, 20.7-89.1 years). The median time from diagnosis of breast cancer to initial CT examination was 14.1 weeks (range, -3.7 to 296 weeks). The presence of at least one hepatic lesion deemed TSTC was reported in 277 of 941 women (29.4%) in whom no definite hepatic metastasis was reported. Subsequent imaging examinations were performed in 191 of the 277 women (69.0%) (median time from initial CT to last follow-up imaging examination, 54 weeks; range, 0.3-302 weeks). Those examinations revealed the lesions were unchanged in 175 (91.6%) women, no longer visible in eight (4.2%), and larger in six (3.1%). In two women (1.0%), change could not be determined. The enlarging hepatic lesions deemed TSTC represented metastatic breast cancer (three patients), metastatic pancreatic cancer (one patient), or cysts (one patient); in one patient, the etiology was not known. Results of best- and worst-case analyses showed that the lesions were benign in 96.9% (95% CI: 93%, 99%) and 92.7% (95% CI: 88%, 96%) of women, respectively. CONCLUSION: In 92.7%-96.9% of women with breast cancer and hepatic lesions deemed TSTC but no definite liver metastases at initial CT, the lesions represented a benign finding.     

Pulmonary tumorlets: CT findings

OBJECTIVE: Pulmonary tumorlets are defined in pathologic terms as benign localized neuroendocrine cell proliferations a few millimeters in size that are usually associated with damaged and ectatic small airways. The purpose of this study was to determine the frequency with which pulmonary tumorlets can be seen on CT and to describe their CT appearance. CONCLUSION: In 33 patients with proven tumorlets, a nodule was visible on CT in the same region as that of the resected specimen. Despite its ominous-sounding name, a pulmonary tumorlet represents benign tissue that may manifest as a subcentimeter pulmonary nodule and should be considered in the differential diagnosis of small pulmonary nodules visible on CT.     

Breath-hold magnetic resonance cholangiopancreatography in the evaluation of malignant pancreaticobiliary obstruction

OBJECTIVE: This study was designed to determine the effectiveness of magnetic resonance cholangiopancreatography (MRCP) using a breath-hold single-shot fast spin echo (SSFSE) technique in imaging patients with malignant biliary and/or pancreatic duct obstruction. METHODS: One hundred thirty-one breath-hold MRCP studies in patients with malignant pancreatic and/or biliary obstruction were evaluated. Pathologic diagnoses included pancreatic cancer, biliary malignancy, gallbladder carcinoma, hepatic neoplasms, malignant lymphadenopathy, and ampullary carcinoma. Two observers independently reviewed the images in a blinded fashion to assess the level of obstruction and the site of underlying tumor. RESULTS: The level of obstruction was correctly identified in 104 of 131 cases (79%) by observer 1 and in 107 of 131 cases (82%) by observer 2. The site of underlying tumor was correctly identified in 113 of 131 cases (86%) by observer 1 and in 110 of 131 cases (84%) by observer 2. CONCLUSION: Magnetic resonance cholangiopancreatography utilizing the SSFSE technique can accurately assess the level of obstruction and the site of underlying tumor in patients with malignant pancreaticobiliary obstruction, without the risks of cholangiography. This MRCP technique allows for visualization of intra- and extraductal anatomy and pathology.