Chitra Viswanathan

Inflammatory Pseudotumor: The Great Mimicker

OBJECTIVE The purpose of this review is to describe the pathophysiologic findings, differential diagnosis, imaging features, and management of inflammatory pseudotumor in various locations throughout the body. CONCLUSION Inflammatory pseudotumor is a rare benign process mimicking malignant processes and has been found in almost every organ system. Radiologists should be familiar with this entity as a diagnostic consideration to avoid unnecessary surgery.

Clinical utility of PET/CT in lymphoma

OBJECTIVE The purpose of this review is to assist interpreting radiologists in becoming familiar with the role of PET/CT in baseline staging and therapeutic response assessment in the management of lymphoma, in becoming aware of imaging pitfalls, and in understanding the natural behavior of lymphoma and the therapeutic options. CONCLUSION Therapeutic strategies for the management of lymphoma are constantly being refined to improve long-term survival with the lowest risk of toxicity to the patient. PET/CT is accurate for baseline staging and yields important prognostic information for determining the most appropriate initial treatment. Used for evaluation of treatment response, PET/CT can depict residual viable malignant lesions with greater accuracy than can other imaging techniques. The findings thereby influence decisions about the need for additional or alternative treatment.

The inguinal canal: anatomy and imaging features of common and uncommon masses.

A variety of benign and malignant masses can be found in the inguinal canal (IC). Benign causes of masses in the IC include spermatic cord lipoma, hematoma, abscess, neurofibroma, varicocele, desmoid tumor, air, bowel contrast material, hydrocele, and prostheses. Primary neoplasms of the IC include liposarcoma, Burkitt lymphoma, testicular carcinoma, and sarcoma. Metastases to the IC can occur from alveolar rhabdomyosarcoma, monophasic sarcoma, prostate cancer, Wilms tumor, carcinoid tumor, melanoma, or pancreatic cancer. In patients with a known malignancy and peritoneal carcinomatosis, the diagnosis of metastases can be suggested when a mass is detected in the IC. When peritoneal disease is not evident, a mass in the IC is indicative of stage IV disease and may significantly alter clinical and surgical treatment of the patient. A combination of the clinical history, symptoms, laboratory values, and radiologic features aids the radiologist in accurately diagnosing mass lesions of the IC. Supplemental material available at radiographics.rsnajnls.org/cgi/content/full/28/3/819/DC1.

The reversed halo sign: update and differential diagnosis

The reversed halo sign is characterised by a central ground-glass opacity surrounded by denser air-space consolidation in the shape of a crescent or a ring. It was first described on high-resolution CT as being specific for cryptogenic organising pneumonia. Since then, the reversed halo sign has been reported in association with a wide range of pulmonary diseases, including invasive pulmonary fungal infections, paracoccidioidomycosis, pneumocystis pneumonia, tuberculosis, community-acquired pneumonia, lymphomatoid granulomatosis, Wegener granulomatosis, lipoid pneumonia and sarcoidosis. It is also seen in pulmonary neoplasms and infarction, and following radiation therapy and radiofrequency ablation of pulmonary malignancies. In this article, we present the spectrum of neoplastic and non-neoplastic diseases that may show the reversed halo sign and offer helpful clues for assisting in the differential diagnosis. By integrating the patients clinical history with the presence of the reversed halo sign and other accompanying radiological findings, the radiologist should be able to narrow the differential diagnosis substantially, and may be able to provide a presumptive final diagnosis, which may obviate the need for biopsy in selected cases, especially in the immunosuppressed population.

Positron Emission Tomography/computed Tomography in Lung Cancer Staging, Prognosis, and Assessment of Therapeutic Response

Positron emission tomography (PET)/computed tomographic scanning, using 18F-2-deoxy-D-glucose, complements conventional imaging evaluation of patients with lung cancer. The strength of PET scanning lies in the detection of nodal and extrathoracic metastases. PET scanning is also currently being studied in the assessment of prognosis and therapeutic response and has the potential to alter management of oncologic patients. This review will discuss the role of PET/computed tomographic scanning in the diagnosis, staging, and evaluation of prognosis and treatment response in patients with lung cancer.

Neuroimaging of ventriculoperitoneal shunt complications in children.

The ventriculoperitoneal shunt is the mainstay of treatment for hydrocephalus. Despite its widespread use and safety record, it often malfunctions due to complications such as obstruction, breakage, migration and infection. This necessitates a systematic approach to diagnosing the etiology of shunt failure. Any evaluation should begin with an appraisal of the patient’s symptoms. In acute malfunction, nausea, vomiting, irritability, seizures, headache, lethargy, coma and stupor are seen. In chronic malfunction, neuropsychological signs, feeding pattern changes, developmental delay, decline in school performance, headaches and increased head size are often seen. The next step in evaluation is a CT scan of the head to evaluate ventricular size. Prior imaging studies should be obtained for comparison; if the ventricles have enlarged over time, shunt malfunction is likely. If there is no such increase or dilation in the first place, other diagnoses are possible. However, “slit ventricle syndrome” should also be considered. When prior imaging is not available, pumping the reservoir, a radionuclide shuntogram, a shunt tap or even surgical exploration are options. The goals of this paper are to provide an algorithm for evaluating shunt malfunction and to illustrate the radiographic findings associated with shunt failure.

Malignant Pleural Mesothelioma: Role of CT, MRI, and PET/CT in Staging Evaluation and Treatment Considerations

Malignant pleural mesothelioma (MPM) is the most common primary malignant pleural neoplasm, arising from mesothelial cells. The annual incidence is 3000 cases in the United States. MPM is associated with exposure to asbestos in up to 80% of patients. Owing to the latency period of up to 50 years for mesothelioma to develop from the time of asbestos exposure, the worldwide figure is expected to increase over the next decade. The prognosis is poor with a median survival of 9-17 months after diagnosis, and there is no universally accepted standard therapeutic regimen. Advances in the treatment of patients with MPM over the past few years include a unified staging system, novel targeted agents, improved radiation therapy techniques for local control, and decreased morbidity and mortality in patients who undergo curative surgical resection. In addition, the failure of single-modality therapy has led to the increasing use of multimodality regimens combining chemotherapy, radiotherapy, and surgery. In patients with early stage disease, there has been an increasing tendency to perform surgical resection as part of the treatment algorithm. Patients with epithelial histology, a primary tumor that is limited in local extent, and no nodal metastases have the greatest survival benefit following surgical resection. Conversely, patients with sarcomatoid histology and nodal metastases have shown poor overall survival after resection and may be treated with palliative chemotherapy. In terms of chemotherapeutic regimens, the use of the antifolate, pemetrexed, in combination with cisplatin has been reported to improve overall survival by 3 months and is generally accepted as standard therapy for MPM. To optimally evaluate the effectiveness of new treatment options, accurate staging to stratify patients into homogeneous groups for entry into clinical trials is needed.

Complications of oncologic therapy in the abdomen and pelvis: a review

Cancer therapy has significantly improved in the past few decades with development of various newer classes of cytotoxic chemotherapy as well as novel, molecularly targeted chemotherapy. Similar to chemotherapy, radiotherapy is another important therapeutic option used in the curative and palliative management of various abdominal malignancies. However, both these treatments affect the tumor as well as the normal tissues, leading to significant toxicity. These side effects range from mild to life threatening, and may involve multiple organs. Imaging plays an important role in the early identification of such complications, which may allow more effective patient management. The aim of this article is to discuss and illustrate the wide spectrum of chemotherapy and radiotherapy induced complications in the abdomen and pelvis.

Tuberculosis: A Benign Impostor

OBJECTIVE The purpose of this article is to illustrate the overlapping radiologic patterns in proven tuberculosis cases in patients initially referred to our cancer center for presumed malignancy. CONCLUSION Tuberculosis can simulate malignancy both clinically and radiologically, especially in its extrapulmonary form.

What Is the Clinical Significance of FDG Unexpected Uptake in the Prostate in Patients Undergoing PET/CT for Other Malignancies?

Purpose. To determine the clinical significance of unexpected, abnormal FDG uptake in the prostate in patients undergoing FDG-PET/CT for staging of other primary malignancies without a prior history of prostate carcinoma. Methods. Retrospective search of FDG-PET/CT studies to identify patients with unexpected, abnormal FDG uptake in the prostate gland, who underwent subsequent biopsy, was performed. 26 patients were identified. Images were reviewed to determine the pattern of uptake within the prostate (focal or diffuse) and maximum standardized uptake value (SUVmax). PSA and Gleason scores were recorded. Results. 15/26 (58%) patients were found to have prostate carcinoma. Gleason scores ranged from 6 to 9.9. There was no statistical difference in the pattern of uptake (focal versus diffuse) or the SUVmax. Serum PSA levels with cancer (range, 2–26.8 ng; mean, 10.2 ng) and those without cancer (range, 2–10.5 ng; mean, 2.2 ng) were statistically significant (P < 0.007, Wilcoxon rank sum test). Conclusions. Patients with abnormal uptake in the prostate have a 58% likelihood of occult prostate cancer. In the setting of elevated serum PSA levels, abnormal prostate uptake should therefore be viewed with suspicion and a urology consult should be obtained; however, it is irrelevant in patients with underlying aggressive malignancies.