Faculty Bibliography

OBJECTIVE:The objective of this study was to compare the efficacy of surveillance high-resolution computed tomography (HRCT) and physical examination/endoscopy (PE/E) with the efficacy of fluorodeoxyglucose (FDG)-positron emission tomography (PET)/HRCT for the detection of relapse in head and neck squamous cell carcinoma (HNSCC) after primary treatment. METHODS:This is a retrospective analysis of contemporaneously performed FDG-PET/HRCT, neck HRCT, and PE/E in 99 curatively treated patients with HNSCC during post-therapy surveillance to compare performance test characteristics in the detection of early recurrence or second primary cancer. RESULTS:Relapse occurred in 19 of 99 patients (20%) during a median follow-up of 21 months (range: 9-52 months). Median time to first PET/HRCT was 3.5 months. The median time to radiological recurrence was 6 months (range: 2.3-32 months). FDG-PET/HRCT detected more disease recurrences or second primary cancers and did so earlier than HRCT or PE/E. The sensitivity, specificity, and positive and negative predictive values for detecting locoregional and distant recurrence or second primary cancer were 100%, 87.3%, 56.5%, and 100%, respectively, for PET/HRCT versus 61.5%, 94.9%, 66.7%, and 93.8%, respectively, for HRCT versus 23.1%, 98.7%, 75%, and 88.6%, respectively, for PE/E. In 19 patients with true positive PET/HRCT findings, a significant change in the management of disease occurred, prompting either salvage or systemic therapy. Of the 14 curatively treated patients, 11 were alive with without disease at a median follow-up of 31.5 months. CONCLUSION/CONCLUSIONS:FDG-PET/HRCT has a high sensitivity in the early detection of relapse or second primary cancer in patients with HNSCC, with significant management implications. Given improvements in therapy and changes in HNSCC biology, appropriate modifications in current post-therapy surveillance may be required to determine effective salvage or definitive therapies.

We sought to determine whether laboratory parameters could be found, predictive of a negative abdominal CT scan in young adults with nontraumatic abdominal pain. Following institutional review board approval, we evaluated CT reports of 522 patients, aged 21-35 years old, who presented to the Emergency Department with nontraumatic abdominal pain. Bivariate analyses relating ten laboratory parameters to whether the CT detected a cause for abdominal pain were conducted. A multivariate logistic regression model was then derived, with all variables in the final model significant at p < 0.05. Variables were dichotomized to yield odds ratios and 95% confidence intervals. Of the 522 patients meeting inclusion criteria, 45% had a cause for pain demonstrated by CT. Predictors of a negative CT in men were normal hematocrit and negative urine blood (p = 0.045, p = 0.016, respectively), and in women normal hematocrit, granulocyte percent, and alkaline phosphatase (p = 0.023, p = 0.039, p < 0.0001, respectively). When standard normal values were used to calculate descriptive statistics, only granulocyte percent in women had a significant confidence interval (odds ratio 2.5, confidence interval 1.6-4.0). Among the 208 women with normal granulocyte percent, the final clinical diagnosis was appendicitis, cholecystitis, and diverticulitis, in three, three, and two cases, respectively (4% combined). In summary, no laboratory test was sufficient to offer reassurance that a CT is not necessary in a young adult patient with nontraumatic abdominal pain. Alternative strategies should be considered to decrease the use of CT, and its associated radiation exposure, in young adults with nontraumatic abdominal pain.

PURPOSE/OBJECTIVE:Advances in medical imaging have been associated with increased utilization and increased radiation exposure, especially for patients with chronic and recurrent conditions. The authors estimated the cumulative radiation doses from medical imaging for specific cohorts with chronic and recurrent conditions. METHODS:All patients diagnosed with hydrocephalus (n = 1,711), pulmonary thromboembolic disease (n = 3,220), renal colic (n = 5,855), and cardiac disease (n = 11,072) from January 1, 2000, to December 31, 2005, were retrospectively identified. Each imaging examination that used ionizing radiation from 2000 to 2008 was incorporated into an estimate of total effective dose and organ-specific doses. Patients with high levels of radiation exposure after 3 years (total effective dose > 50 mSv; dose to the ocular lens > 150 mSv) were identified. RESULTS:The mean estimated effective doses for the surviving diagnostic cohorts after 3 years were 12.3 mSv for patients with hydrocephalus, 21.7 mSv for those with pulmonary thromboembolic disease, 18.7 mSv for those with renal colic, and 14.0 mSv for those with cardiac disease. Among patients with hydrocephalus, 26.3% (339 of 1,291) had radiation doses > 150 mSv to the ocular lens within 3 years. In all cohorts, the proportion of patients with total effective doses > 50 mSv within 3 years was significantly higher for those diagnosed in 2004 and 2005 than for those diagnosed in 2000 and 2001. CONCLUSION/CONCLUSIONS:Patients with hydrocephalus, pulmonary thromboembolic disease, renal colic, and cardiac disease received radiation exposures that may put them at increased risk for cancer. Moreover, the proportion who received estimated total effective doses > 50 mSv within 3 years was significantly higher for those diagnosed most recently. It is the responsibility of institutions and physicians to critically evaluate their infrastructures, diagnostic strategies, and imaging techniques for each individual patient, with an eye toward minimizing cumulative medical radiation exposure.

OBJECTIVE:The purpose of our study was to determine whether the radiation exposure to patients with suspected pulmonary embolism (PE) could be decreased by safely increasing the use of ventilation-perfusion (V/Q) scanning and decreasing the use of CT pulmonary angiography (CTPA) through an educational intervention. MATERIALS AND METHODS/METHODS:Collaborative educational seminars were held among the radiology, nuclear medicine, and emergency medicine departments in December 2006 and January 2007 regarding the radiation dose and accuracies of V/Q scanning and CTPA for diagnosing PE. To reduce radiation exposure, an imaging algorithm was introduced in which emergency department patients with a clinical suspicion of PE underwent chest radiography. If the chest radiograph was normal, V/Q scanning was recommended, otherwise CTPA was recommended. We retrospectively tallied the number and results of CTPA and V/Q scanning and calculated mean radiation effective dose before and after the intervention. False-negative findings were defined as subsequent thromboembolism within 90 days. RESULTS:The number of CTPA examinations performed decreased from 1,234 in 2006 to 920 in 2007, and the number of V/Q scans increased from 745 in 2006 to 1,216 in 2007. The mean effective dose was reduced by 20%, from 8.0 mSv in 2006 to 6.4 mSv in 2007 (p < 0.0001). The patients who underwent CTPA and V/Q scanning in 2006 were of similar age. In 2007, the patients who underwent V/Q scanning were significantly younger. There was no significant difference in the false-negative rate (range, 0.8-1.2%) between CTPA and V/Q scanning in 2006 and 2007. CONCLUSION/CONCLUSIONS:The practice patterns of physicians changed in response to an educational intervention, resulting in a reduction in radiation exposure to emergency department patients with suspected PE without compromising patient safety.

OBJECTIVE:To determine the prevalence and clinical significance of normal, variant, and anomalous branching patterns of the aortic arch and the central veins on computed tomographic (CT) angiography in adults. METHODS:We retrospectively reviewed 1000 consecutive CT angiograms of the chest in 658 women and 342 men with a median age of 53 years. RESULTS:A total of 65.9% of patients had both normal aortic arch branching patterns and normal venous anatomy. Variants in the aortic arch branching pattern were present in 32.4% and anomalies in 1.5%. Venous anomalies were present in 0.7%. Review of CT reports showed that cardiothoracic radiologists correctly reported the anomaly more frequently than other radiologists (94% vs 20%, P = 0.003). CONCLUSIONS:Whereas anomalies of the central thoracic vasculature are uncommon, variants in the aortic arch branching pattern are common. An appreciation of the appearance of these entities on CT angiography allows for precise reporting and is useful in preprocedure planning.

After the publication of the Prospective Investigation of Pulmonary Embolism Diagnosis (PIOPED) study in 1990, there was considerable controversy concerning the ventilation-perfusion (V/Q) study in regard to its low sensitivity and high number of nondiagnostic examinations when used in patients with suspected pulmonary embolism (PE). Many lessons have been learned from the PIOPED database that have greatly improved our interpretive skills in the 2 decades since the study was performed. One of the key problems negatively impacting interpretation was the predominantly inpatient population that was studied. Inpatients generally are sicker patients with abnormal chest x-rays. This factor significantly degrades V/Q interpretation. A normal chest x-ray greatly facilitates accurate interpretation of the lung scan. The emergence of computed tomography angiography (CTA) in the early to mid-1990s provided a superb new means of imaging patients with suspected PE. As this technology became more sophisticated with multidetector units, it became the procedure of choice in the great majority of medical centers. CT scanners located in or proximal to many emergency departments as well as its 24/7 availability supported this preference. Within the past 2 to 3 years, the publication of the PIOPED II study as well as some other prospective and retrospective studies have confirmed similar diagnostic accuracy for CTA and V/Q studies. Additionally, there have been several recent publications cautioning physicians about the large radiation dose associated with CTA, particularly to the female breast. Considering the great benefits of both techniques as well as their limitations, it is prudent for both clinicians and imaging physicians to develop an appropriate approach to studying patients with suspected PE. Considerations such as objective clinical assessment, D-dimer assay and the chest x-ray appearance all play significant roles in this decision-making process.

A new technique for percutaneous gastrostomy of a decompressed excluded gastric segment after Roux-en-Y gastric bypass (RYGBP) surgery is described and the results in a single institution are reviewed. Computed tomography guidance was used to place a 21- or 22-gauge needle into the lumen of the stomach and distend it to allow placement of a feeding catheter. Ten women underwent the procedure, and despite only three patients having clear access windows, gastrostomy placement was ultimately successful in all 10 patients. Percutaneous gastrostomy of the decompressed excluded gastric segment after RYGBP surgery can be challenging, but a high rate of success can be achieved.

Failure to treat deep vein thrombosis (DVT) is associated with significant morbidity and mortality. Anticoagulation, although effective at preventing clot progression, is not able to prevent postthrombotic syndrome. Catheter-directed thrombolysis is a more aggressive alternative, with some small studies suggesting a better long-term outcome, but the associated risks are significant, and the treatment can require 2-3 days in a monitored setting. This report describes the power pulse technique, in which mechanical thrombectomy is combined with thrombolytic agents to maximize the effectiveness of the treatment and reduce the need for prolonged infusion and its associated risks. A 24-patient retrospective study showed complete thrombus removal (>90%) in 12 patients, substantial thrombus removal (50%-90%) in seven patients, and partial thrombus removal (<50%) in five patients. All 24 patients had resolution of presenting symptoms. Only two patients required blood transfusion, and one patient experienced temporary nephropathy.

Tyrosine 984 in the juxtamembrane region of the insulin receptor, between the transmembrane helix and the cytoplasmic tyrosine kinase domain, is conserved among all insulin receptor-like proteins from hydra to humans. Crystallographic studies of the tyrosine kinase domain and proximal juxtamembrane region reveal that Tyr-984 interacts with several other conserved residues in the N-terminal lobe of the kinase domain, stabilizing a catalytically nonproductive position of alpha-helix C. Steady-state kinetics measurements on the soluble kinase domain demonstrate that replacement of Tyr-984 with phenylalanine results in a 4-fold increase in kcat in the unphosphorylated (basal state) enzyme. Moreover, mutation of Tyr-984 in the full-length insulin receptor results in significantly elevated receptor phosphorylation levels in cells, both in the absence of insulin and following insulin stimulation. These data demonstrate that Tyr-984 plays an important structural role in maintaining the quiescent, basal state of the insulin receptor. In addition, the structural studies suggest a possible target site for small molecule activators of the insulin receptor, with potential use in the treatment of noninsulin-dependent diabetes mellitus