Unusual Pulmonary Arterial Filling Defect caused by Systemic to Pulmonary Shunt in the Setting of Chronic Lung Disease Demonstrated by Dynamic 4D CTA.

Even though pulmonary embolism is by far the most common cause of filling defect in the pulmonary arterial system, other less common etiologies should be considered especially in the setting of atypical clinical scenario or unusual imaging findings. Unusual pattern of filling defect in the pulmonary artery in the setting of chronic inflammatory/fibrotic parenchymal lung disease should raise the concern for systemic to pulmonary artery shunt. This diagnosis is typically made by conventional angiography. Dynamic 4D CT angiography however can be a safe, noninvasive and effective alternative tool for making such a diagnosis. It has the added value of multiplanar reconstruction capabilities and providing detailed anatomy which can be vital for interventional radiologists when planning their approach for possible intervention. We present 2 cases of such shunts, and illustrate the demonstration of these shunts by using dynamic 4D CT angiography.

Transaortic video-assisted resection of a recurrent left ventricular myxoma.

An asymptomatic 57-year-old woman presented for resection of a fifth cardiac myxoma. To avoid complete redissection of the heart, we proposed a video-assisted transaortic approach for a recurrent left ventricle (LV) myxoma resection. In a hybrid approach, sternotomy and open aortotomy provided the minimally invasive transaortic access to the myxoma. The myxoma was discovered during a routine echocardiographic screening. A 30° 5-mm scope, video-assisted thoracic surgery graspers, and endoshears were used for resection. The video-assisted technique significantly enhanced the intracardiac visualization, and a smaller, second myxoma was discovered after resection of the primary lesion. Both myxoma beds were additionally ablated to prevent recurrence. The total video-assisted operating time was 58 minutes. The transaortic valve approach avoided an atriotomy or ventriculotomy in a fifth redo operation. A transaortic valve approach to LV intracardiac lesions is safe and feasible, and it provides excellent visibility for complex cardiac cases.

Pleural silicone granuloma mimics pleural metastasis: Ruptured breast implant with silicone fistulising along a remote thoracotomy scar.

Silicone gel from ruptured implants can migrate to locations such as the chest wall, axillae, and upper extremities, resulting in granulomatous inflammation. Pleural silicone granulomas have rarely been reported in the literature. This is a rare case of pleural silicone granuloma, which demonstrates that silicone gel from an extracapsular implant rupture can fistulise into the pleural space along a remote thoracotomy scar.

Reduction in radiation dose in mercaptoacetyltriglycerine renography with enhanced planar processing.

PURPOSE: To determine the minimum dose of technetium 99m ((99m)Tc) mercaptoacetyltriglycerine (MAG3) needed to perform dynamic renal scintigraphy in the pediatric population without loss of diagnostic quality or accurate quantification of renal function and to investigate whether adaptive noise reduction could help further reduce the minimum dose required. MATERIALS AND METHODS: Approval for this retrospective study was obtained from the institutional review board, with waiver of informed consent. A retrospective review was conducted in 33 pediatric patients consecutively referred for a (99m)Tc-MAG3 study. In each patient, a 20-minute dynamic study was performed after administration of 7.4 MBq/kg. Binomial subsampling was used to simulate studies performed with 50%, 30%, 20%, and 10% of the administered dose. Four nuclear medicine physicians independently reviewed the original and subsampled images, with and without noise reduction, for image quality. Two observers independently performed a quantitative analysis of renal function. Subjective rater confidence was analyzed by using a logistic regression model, and the quantitative analysis was performed by using the paired Student t test. RESULTS: Reducing the administered dose to 30% did not substantially affect image quality, with or without noise reduction. When the dose was reduced to 20%, there was a slight but significant decrease (P = .0074) in image quality, which resolved with noise reduction. Reducing the dose to 10% caused a decrease in image quality (P = .0003) that was not corrected with noise reduction. However, the dose could be reduced to 10% without a substantial change in the quantitative evaluation of renal function independent of the application of noise reduction. CONCLUSION: Decreasing the dose of (99m)Tc-MAG3 from 7.4 to 2.2 MBq/kg did not compromise image quality. With noise reduction, the dose can be reduced to 1.5 MBq/kg without subjective loss in image quality. The quantitative evaluation of renal function was not substantially altered, even with a theoretical dose as low as 0.74 MBq/kg.

Dual phase FDG-PET imaging of brain metastases provides superior assessment of recurrence versus post-treatment necrosis.

To study the ability of dual phase FDG-PET/CT imaging to accurately distinguish tumor versus necrosis in patients treated for brain metastases. 32 (22 female, 10 male) consecutive patients with treated brain metastases, lesion size greater than 0.5 cm(3) and suspected recurrence on MRI underwent dual-phase FDG-PET/CT. Clinical outcome was assessed by biopsy or by MRI. SUVmax and SUVmean values of the lesion (L) and gray matter (GM) at the level of the thalamus were measured on early (1) and delayed (2) imaging. L1/GM1 and L2/GM2 and the change of L/GM ratios as a function of time were calculated [(L2/GM2 - L1/GM1)/(L1/GM1)]. Cut-off values were obtained by ROC analysis. P < 0.05 defined statistical significance. Seven patients were excluded due to indeterminate outcomes. 25 patients (16 female, 9 male; 27 lesions; 28 scan sessions) had clear outcomes, proven by either biopsy (n = 16 patients) or serial follow-up MRI (n = 9 patients). Primary subtypes included breast (n = 9), lung (n = 7), melanoma (n = 3), squamous cell cancer of the head and neck (n = 2) and other (n = 4). Twenty-two patients underwent prior radiation (2-113 months) and three received only prior chemotherapy (5 months to 3 years). A change >0.19 of L/GM ratios as a function of time was 95% sensitive, 100% specific, and 96.4% accurate (P = 0.0001; AUC = 0.97) for distinguishing tumor versus radiation necrosis. The ratio of the change of the lesion to WM ratios over time was the second best indicator of outcome when compared to all indices used (ROC cut-off = 0.25, sensitivity 89.5% and specificity 90.9%, and accuracy 89.2%; P = 0.0001; AUC = 0.95), Early or late SUVs of the lesion alone did not differentiate between tumor and necrosis. Regardless of histological type, differentiation of necrosis from metastatic brain lesions was improved by using the change of lesion to gray matter SUVmax ratios as a function of time.

CT coronary angiography: 256-slice and 320-detector row scanners.

Multidetector computed tomography (MDCT) has rapidly evolved from 4-detector row systems in 1998 to 256-slice and 320-detector row CT systems. With smaller detector element size and faster gantry rotation speed, spatial and temporal resolution of the 64-detector MDCT scanners have made coronary artery imaging a reliable clinical test. Wide-area coverage MDCT, such as the 256-slice and 320-detector row MDCT scanners, has enabled volumetric imaging of the entire heart free of stair-step artifacts at a single time point within one cardiac cycle. It is hoped that these improvements will be realized with greater diagnostic accuracy of CT coronary angiography. Such scanners hold promise in performing a rapid high quality "triple rule-out" test without high contrast load, improved myocardial perfusion imaging, and even four-dimensional CT subtraction angiography. These emerging technical advances and novel applications will continue to change the way we study coronary artery disease beyond detecting luminal stenosis.

Clinical Role of Hybrid Imaging.

Recent technological advances have fueled the growth in hybrid radionuclide and CT imaging of the heart. Noninvasive imaging studies are reliable means to diagnose coronary artery disease (CAD), stratify risk, and guide clinical management. Myocardial perfusion scintigraphy is a robust, widely available noninvasive modality for the evaluation of ischemia from known or suspected CAD. Cardiac CT (coronary artery calcium score and coronary CT angiography) has emerged as a clinically robust noninvasive anatomic imaging test, capable of rapidly diagnosing or excluding obstructive CAD. Both anatomic and functional modalities have strengths and weaknesses, and can complement each other by offering integrated structural and physiologic information. As we discuss below, in selected patients, hybrid imaging may facilitate more accurate diagnosis, risk stratification, and management in a "one-stop shop" setting.