MRI of Emergent Intracranial Infections and Their Complications.

Acute intracranial infections of the central nervous system and skull base are uncommon but time sensitive diagnoses that may present to the emergency department. As symptoms are frequently nonspecific or lack typical features of an infectious process, a high index of suspicion is required to confidently make the diagnosis, and imaging may not only serve as the first clue to an intracranial infection, but is often necessary to completely characterize the disease process and exclude any confounding conditions. Although computed tomography is typically the initial imaging modality for many of these patients, magnetic resonance imaging offers greater sensitivity and specificity in diagnosing intracranial infections, characterizing the full extent of infection, and identifying potential complications. The aim of this article is to serve as a review of the typical and most important imaging manifestations of these infections that can be encountered in the emergent setting.

Spine MRI: A Review of Commonly Encountered Emergent Conditions.

Over the last 2 decades, the proliferation of magnetic resonance imaging (MRI) availability and continuous improvements in acquisition speeds have led to significantly increased MRI utilization across the health care system, and MRI studies are increasingly ordered in the emergent setting. Depending on the clinical presentation, MRI can yield vital diagnostic information not detectable with other imaging modalities. The aim of this text is to report on the up-to-date indications for MRI of the spine in the ED, and review the various MRI appearances of commonly encountered acute spine pathology, including traumatic injuries, acute non traumatic myelopathy, infection, neoplasia, degenerative disc disease, and postoperative complications. Imaging review will focus on the aspects of the disease process that are not readily resolved with other modalities.

Imaging evaluation of diaphragmatic injuries: Improving interpretation accuracy.

Diaphragmatic Injuries (DIs) remain a challenging diagnosis with potential catastrophic delayed complications. A high degree of suspicion in every case of severe blunt thoracoabdominal trauma or penetrating thoracoabdominal injury is essential. This review will present the evidence and controversies on this topic providing a practical tutorial for radiologists hoping to improve their interpretive accuracy for both blunt and penetrating DIs. The imaging signs of diaphragmatic injuries will be explained with emphasis on multidetector CT. Diagnostic pitfalls, available protocols and other issues will be presented.

ECG-gated cardiac MDCT for detection of systolic anterior motion of mitral valve.

OBJECTIVES: Evaluating ECG-gated cardiac MDCT detection of systolic anterior motion of the mitral valve, in comparison to trans-thoracic echocardiography as a gold standard. MATERIALS AND METHODS: Study group included 83 consecutive patients (57 men; average age 56.1 years) evaluated with both retrospective ECG-gated cardiac MDCT and trans-thoracic echocardiography within an interval of 30 days. ECG-gated cardiac MDCT imaging was performed with retrospective ECG- gating using 64-slice and 128-slice CT scanners with an inherent temporal resolution range of 75-165 ms. MDCT's and trans- thoracic echocardiograms were retrospectively and independently evaluated by experienced radiologist and cardiologist respectively, for presence of systolic anterior motion of the mitral valve. RESULTS: 7 patients (8.4%) were found to have systolic anterior motion by trans-thoracic echocardiography, from which 6 were found to have systolic anterior motion by ECG-gated cardiac MDCT. Of the 76 patients without systolic anterior motion on trans-thoracic echocardiography, all were correctly identified using ECG-gated cardiac MDCT. The sensitivity, specificity, positive and negative predictive values and accuracy of ECG-gated cardiac MDCT in identifying systolic anterior motion of the mitral valve were 85.7% (6/7), 100% (76/76), 100% (6/6), 98.7% (76/77) and 98.8% (82/83), respectively. CONCLUSION: ECG-gated cardiac MDCT is comparable to trans-thoracic echocardiography in detecting systolic anterior motion of the mitral valve.

PET/CT image fusion error due to urinary bladder filling changes: consequence and correction.

OBJECTIVE: A considerable change of urinary bladder (UB) shape in PET compared with CT in integrated PET/CT system is frequently noted. This study initially evaluated this finding with and without oral contrast (OC) use. In addition, a one bed pelvic section (PLV) repeat acquisition was investigated as a solution to this problem. METHODS: (18)FDG PET/CTs of 88 patients were analyzed. OC was administered in 68 patients, of whom 31 had PLV images taken 5-10 min later. Three-dimensional mid-UB CT and PET matching measurements were compared. In addition, UB walls displacement between CT and PET were analyzed. RESULTS: The mean UB height was significantly increased (P < 0.001) in PET when compared with CT, both anteriorly and posteriorly; however, UB width and depth were not significantly different. An upward shift of superior UB wall in PET from equivalent CT images was noted, whereas there was no appreciable displacement of the other UB walls. The percent UB height increase on PET from CT was significantly greater with than without OC use. The UB height difference between PET and CT was markedly reduced on PLV when compared with the original scans. CONCLUSIONS: Caution should be exerted during the interpretation of PET/CT scans of the pelvis as there is significant upward expansion of UB on PET compared with CT that appears to be exaggerated by OC use, likely due to additional fluid load. The PET/CT fusion errors of UB can be substantially resolved through a separate PLV acquisition presumably due to the shorter time interval of UB scan completion between CT and PET.

Value of precise localization of recurrent multiple myeloma with F-18 FDG PET/CT.

A 37-year-old man with multiple myeloma in remission underwent routine fluorodeoxyglucose-positron emission tomography/computed tomography (FDG-PET/CT) study for disease restaging. Both FDG-PET and CT images showed focal abnormalities in the region of the T6 vertebra, but the fused images that are routinely provided with PET/CT could precisely localize the FDG active lesion to a soft tissue focus in the epidural space, away from a lytic nonactive vertebral body lesion despite their close proximity. The PET/CT scan identified a few other metabolically active osseous lesions out of many lytic bony changes throughout the skeleton. Accordingly, the patient received the correct management for an impending spinal cord compression at the appropriate time, in addition to systemic therapy for disease relapse.

Impact of PET/CT in comparison with same day contrast enhanced CT in breast cancer management.

PURPOSE: To evaluate the impact of F-18 fluorodeoxyglucose (FDG) positron emission tomography with fused computerized tomography (PET/CT) in comparison with same day contrast enhanced CT (CE-CT) in breast cancer management. METHOD: Seventy studies in 49 breast cancer patients, 17 for initial and 53 for restaging disease were included. All patients underwent PET/CT for diagnostic purposes followed by CE-CT scans of selected body regions. PET/CT was started approximately 90 minutes following IV injection of 10-15 mCi of F-18 FDG on a GE Discovery PET/CT system. Oral contrast was given before F-18 FDG injection. The CE-CT was performed according to departmental protocol. RESULTS: Out of a total of 257 lesions, 210 were concordant between PET/CT and CE-CT. There were 47 discordant lesions, which were verified by either biopsy (35) or follow-up (12 PET positive CE-CT negative lesions). PET/CT correctly identified 25 true positive (TP). CE-CT identified 2 TP lesions missed by PET/CT which were false negatives (FNs): one liver metastasis with necrosis, which was nonavid to FDG uptake because of necrosis and a second one missed on abdominal metastatic node, which did not change staging or treatment. PET/CT incorrectly identified 2 false positive lesions while CE-CT incorrectly identified 18 false positive. TP recurrence of the disease was found by PET/CT in 44% (15/34 pts), whereas 56% (19/34 pts) were free of disease. The CE-CT described progression of the disease in 1 true negative PET/CT study and no progression in 2 TP PET/CT studies. The sensitivity, specificity, accuracy, positive productive value, and negative productive value for PET/CT were 97.8%, 93.5%, 97.3%, 99.1%, 85% and for CE-CT were 87.6%, 42%, 82.1%, 91.6%, 31.7%. CONCLUSION: In this study, PET/CT played a more important role than CE-CT scans alone and provided an impact on the management of breast cancer patients.

Scintigraphic visualization of an epigastric sentinel node in recurrent breast cancer after lumpectomy and postoperative radiation therapy.

Sentinel node imaging and biopsy have become standard procedures for staging early breast cancer. Positive sentinel lymph node (SLN) biopsy necessitates the need for axillary lymph node dissection (ALND). Failure to visualize a sentinel lymph node in recurrent breast cancer after treatment by surgery, chemotherapy, and high-dose postoperative radiation therapy is almost the case in every patient. The reason for failure to visualize the sentinel node is the fibrosis that follows high-dose radiotherapy and blocks the lymphatics preventing spread of the tumor cells to the lymph nodes. Alternative pathways for the drainage of lymph from the breast are developed in these patients. We have previously reported on the alternative pathways of lymphatics to the contralateral axilla, supraclavicular area, and also reported on the development of intramammary lymph nodes. In this report, we are presenting another alternative pathway of lymphatics to the region of the epigastrium below the lower end of the sternum.