Importance of collimator selection for quantitative 131I scintigraphy

Aberrant 131I orthoiodohippurate renal plasma flow values were obtained when our image-based method was moved from an old to a new gamma camera. We suspected inadequate collimation as the reason for this problem because we observed increased septal penetration and scatter. Camera effects were largely eliminated because both our old and new cameras had 1/2' thick crystals. We report here the effects of two high and three medium energy collimators upon the fraction of syringe image count beyond the syringe image, and upon the correlation of these non-image count fractions with geometric collimator parameters. We also report the effects of these same collimators upon kidney-to-background count ratios, using patient relevant abdominal phantoms. The percentage counts beyond the syringe image varied from 33 to 57%. The phantom kidney-to-background ratios varied from 3.7 to 2.0. We conclude that image-based quantitative measurements are strongly dependent on collimator selection. The data also provide a user basis for collimator evaluation, selection and design, and have implications for 131I and 111In antibody imaging.     

105Changes in Nitric Oxide Levels After Deep Dermal injury in the Female,Red Duroc Pig (FRDP)

Introduction : Hypertrophic scar is a devastating sequel to burns and other tangential skin injuries. It follows deep dermal injuries and does not occur after superficial injuries. Nitric oxide (NO) plays many important roles in wound healing from inflammation to scar remodeling. Studies have shown that expression of nitric oxide synthase and nitric oxide production are decreased in human hypertrophic scar. However little is known about NO involvement in the early stages of hypertrophic scarring, because of the lack of an animal model. It was recently reported that the female red Duroc pig (FRDP) makes thick scar, which is similar to human hypertrophic scar. We hypothesized that NO production in wounds on the female, red Duroc pig is similar to that of human hypertrophic scar and that NO involvement in deep wounds is different from that in superficial wounds. Methods : Superficial (0.015” to 0.030”) and deep (0.045” to 0.060”) wounds were created on the backs of four FRDPs. Biopsies were collected at weeks 1.5, 4, 8 and 21 post wounding including samples of uninjured skin. Nitric oxide levels were measured with the Griess reaction assay and normalized with tissue protein level. Results : Superficial wounds healed with an invisible scar whereas the deep wounds healed with scar resembling mild hypertrophic scar. The thickness of the scars from the deep wounds was significantly greater than uninjured skin and healed superficial wounds (p < 0.01). NO levels were increased at 1.5 weeks in deep wounds compared to superficial wounds and uninjured skin (p < 0.05). At 8 weeks, NO levels in deep wounds had returned to the level of uninjured tissue and superficial wounds. By 21 weeks, NO levels had decreased significantly when compared to superficial wounds (p < 0.01). There were no differences in NO levels between uninjured skin and superficial wounds at any time point (p > 0.05). Conclusions : NO production is similar in late, deep wounds on the female, red Duroc pig to that reported in the literature for human hypertrophic scar further validating this animal model. NO production is quite different after deep wounds as compared to superficial wounds in the FRDP. Early elevation in nitric oxide production might account for excessive inflammation in deep wounds that become thick scars in the FRDP. Nitric oxide regulators and effects at early stages of scar formation should be elucidated further and the FRDP appears to be a useful model.     

Diagnosis of breast cancer in women age 40 and younger: delays in diagnosis result from underuse of genetic testing and breast imaging

Background

The impact of newer breast imaging technologies and genetic testing on the detection of breast cancer in women age 40 and younger remains unknown.

Methods

A records review identified 628 women age 40 and younger diagnosed with breast cancer from 1996 to 2008. Patient and tumor characteristics, means of diagnosis, imaging results, and genetic testing were examined.

Results

Tumors were first detected by self-examination in 71%, with a median invasive tumor size of 2.0 cm. Imaging performed at or after diagnosis visualized most tumors; mammography visualized 86%, magnetic resonance imaging (MRI) visualized 96%, and mammography plus MRI visualized more than 98% of tumors. For 81% of patients, the mammogram at diagnosis was their first mammogram. Although 50% had a family history of breast or ovarian cancer, few underwent genetic testing before their cancer diagnosis; 61 of 247 (25%) ultimately tested had a BRCA mutation.

Conclusions

Better use of genetic testing, mammography, and MRI could improve breast cancer detection in young women.     

Reproducibility of 18F-FDG PET uptake measurements in head and neck squamous cell carcinoma on both PET/CT and PET/MR

Objective:

To investigate reproducibility of fluorine-18 fludeoxyglucose (¹⁸F-FDG) uptake on ¹⁸F-FDG positron emission tomography (PET)/CT and ¹⁸F-FDG PET/MR scans in patients with head and neck squamous cell carcinoma (HNSCC).

Methods:

30 patients with HNSCC were included in this prospective study. The patients were scanned twice before radiotherapy treatment with both PET/CT and PET/MR. Patients were scanned on the same scanners, 3 days apart and according to the same protocol. Metabolic tumour activity was measured by the maximum and peak standardized uptake value (SUV_max and SUV_peak, respectively), and total lesion glycolysis from the metabolic tumour volume defined from ≥50% SUV_max. Bland–Altman analysis with limits of agreement, coefficient of variation (CV) from the two modalities were performed in order to test the reproducibility. Furthermore, CVs from SUV_max and SUV_peak were compared. The area under the curve from cumulative SUV–volume histograms were measured and tested for reproducibility of the distribution of ¹⁸F-FDG uptake.

Results:

24 patients had two pre-treatment PET/CT scans and 21 patients had two pre-treatment PET/MR scans available for further analyses. Mean difference for SUV_max, peak and mean was approximately 4% for PET/CT and 3% for PET/MR, with 95% limits of agreement less than ±20%. CV was small (5–7%) for both modalities. There was no significant difference in CVs between PET/CT and PET/MR (p = 0.31). SUV_max was not more reproducible than SUV_peak (p = 0.09).

Conclusion:

¹⁸F-FDG uptake in PET/CT and PET/MR is highly reproducible and we found no difference in reproducibility between PET/CT and PET/MR.

Advances in knowledge:

This is the first report to test reproducibility of PET/CT and PET/MR.Functional imaging with fluorine-18 fludeoxyglucose positron emission tomography combined with CT (¹⁸F-FDG PET/CT) has been shown to be useful for prognostication of head and neck squamous cell carcinoma (HNSCC),^1–3 and the use of ¹⁸F-FDG PET/CT has also been shown to reduce interobserver variability in target delineation for radiotherapy.^4,5 Furthermore, ¹⁸F-FDG PET/CT can identify regions of the tumour with a high risk of relapse, leading to the idea that ¹⁸F-FDG uptake might be a target for dose painting.^6,7 Finally, ¹⁸F-FDG PET/CT may be used in response evaluation.^8,9 Maximum standardized uptake value (SUV_max) has for many years been the main uptake measurement in prognostic studies for various malignancies. More recent studies have focused on demonstrating prognostic value of PET/CT-based volumetric parameters such as metabolic tumour volume (MTV) and total lesion glycolysis (TLG). MTV is the sum of the volume of voxels with standard uptake value (SUV) exceeding a certain threshold value in a tumour, and TLG is calculated by multiplying MTV and the mean standardized uptake value (SUV_mean) of the MTV. These volume-based PET parameters have increasingly gained interest and have been reported to be significant prognostic factors for various malignancies including HNSCC.^{10–13 18}F-FDG PET/CT is currently not routinely recommended as a diagnostic tool in HNSCC except in very specific situations,¹⁴ but reproducibility of the ¹⁸F-FDG signal is a prerequisite for a more widespread use of ¹⁸F-FDG PET for the above-mentioned indications. Yet, only a few studies of the reproducibility of ¹⁸F-FDG PET/CT exist^8,15–21 and none of these studies includes patients with HNSCC.MRI is gaining acceptance as an imaging modality for oncology as it offers superior soft-tissue contrast compared with CT alone, and it has been suggested that information from PET/CT and MR is complementary in head and neck cancer.²² The introduction of the integrated PET/MR scanner offers a unique opportunity to combine the high soft-tissue contrast of MR with the functional imaging from PET within a single imaging session. PET/MR is still in its infancy, but the combined modality imaging is potentially useful in the management of patients with HNSCC.^22–28 However, the same criteria of reproducibility as with PET/CT should be upheld by this new modality. The purpose of this prospective test–retest study is to assess the reproducibility of both ¹⁸F-FDG PET/CT and ¹⁸F-FDG PET/MR in a homogenous cohort of patients with HNSCC.     

Malignant round cell tumours of bone: atypical clinical and imaging features

Objective.To describe the clinical, radiological and MRI features of six atypical cases of histologically proven appendicular Ewing sarcoma/ primitive neuroectodermal tumour (PNET). Design. Retrospective review of case notes and available imaging was carried out. Patients. Six patients (4 male, 2 female; mean age 27years, range 19–44 years), presenting over a 77-month period, were identified from the Bone Tumour Register. All had unusual clinical and imaging features for Ewing sarcoma/PNET. Results and conclusions. Four tumours were centred on the distal femoral metaphysis, one in the proximal tibial metaphysis and one in the distal tibial metaphysis. Plain radiographs were available in four cases and showed minor cortical changes. MRI demonstrated a relatively small, eccentrically located intraosseous component with a large, eccentric extraosseous component. Extension into the epiphysis was seen in three cases and into the adjacent joint in two cases. Intraosseous ”skip” metastases were present in three cases. The clinical and imaging features were atypical for conventional intraosseous Ewing sarcoma/PNET and the exact site of origin (intraosseous, periosteal or soft-tissue) was unclear. Received: 6 December 1999 Revision requested: 7 February 2000 Revision received: 20 July 2000 Accepted: 4 August 2000     

Prospective, randomized comparison of cobalt-chrome and titanium trilock femoral stems

The purpose of this article was to demonstrate the efficacy of a cementless, flat, tapered wedge femoral stem and compare cobalt-chrome and titanium femoral stems with this design. Three hundred ninety femoral stems observed for a mean of 4.7 years (2.0-8.9 years) were prospectively evaluated with clinical and radiographic follow-up. Hips were stratified by Dorr classification, bone stock (femoral index), size of implant used, and material of femoral implant. Survivorship of the femoral stem at 8.9 years was 99.8% with no significant difference between cohorts. Thigh pain (4.9%) was more common with cobalt-chrome femoral stems (6.5%) than titanium femoral stems (3.1%). The flat, tapered wedge femoral stem design provides excellent femoral reconstruction in total hip arthroplasty. On the basis of this study, we use titanium femoral stems.     

Incidence of sporting injury in New Zealand youths aged 6-15 years

OBJECTIVE: To document the incidence of injury in 6-15 year olds playing rugby union, rugby league, and netball, and to identify the common mechanisms, sites, severity, and time of injury. METHODS: Cross sectional data were collected by trained observers who watched 258 games of rugby union, netball, and rugby league over a four week period. The condition of the injured participants was monitored until recovery. RESULTS: In total, 5174 players were observed and an injury rate of 18 per 1000 player hours was calculated. Of all observed injuries, 29% required some form of medical treatment. A significant difference (p<0.05) in the distribution of injury over the four quarters of the games was recorded, most occurring in the first three quarters. In total, 81% of the injuries were classified as contact injuries, and these mainly occurred through direct contact with the opposition. Of all observed injuries, 27% were recurrent. CONCLUSIONS: The incidence of injury in rugby union, netball, and rugby league is low for children aged between 6 and 15 years relative to adult rates.


     

Prevention of surgical site infection by antibiotic spraying in the operative field during cardiac surgery

OBJECTIVE: Despite the many procedures introduced to prevent surgical site infection during cardiothoracic surgery, serious infections still occur. We attempted to reduce surgical site infection by spraying antibiotic solution in the operative field--a procedure since introduced at 4 other Japanese institutions. METHODS: In the latter half of 1990, we began spraying an antibiotic solution of cefazolin (1g) and gentamicin (40 mg)/40 ml of saline placed in a 50 ml syringe and dispensed through an 18 G needle bent at 60 to 80 degrees to clean the wound during surgery. RESULT: No deep surgical site infections or deaths due to infection have occurred among the 502 patients undergoing cardiothoracic surgery under cardiopulmonary bypass at our hospital. This method was used in over 2,100 cases of similar procedures at 4 other institutions. There were 3 deaths due to severe surgical site infection (0.11%). At one institution treating over 1,000 cases a year, the incidence of death due to surgical site infection decreased significantly after this method was introduced. CONCLUSION: These preliminary experiences show that spraying antibiotic solution in the operative field reduces the risk of surgical site infection in cardiothoracic surgery.     

Detection of left ventricular dysfunction after acute myocardial infarction: comparison of clinical, echocardiographic, and neurohormonal methods.

OBJECTIVE--The SAVE study showed that captopril improves mortality in patients with left ventricular dysfunction after myocardial infarction and that this benefit occurred even in patients with no clinically overt heart failure. On the basis of this, it seems important to identify correctly which patients have left ventricular dysfunction after a myocardial infarction. The objective was to compare various methods of identifying patients with left ventricular dysfunction (left ventricular ejection fraction, LVEF, < or = 40%) after acute myocardial infarction. The methods compared were echocardiography (quantitative and qualitative visual assessment), clinical evaluation (subjective assessment and three clinical score methods), and measurement of plasma concentrations of cardiac natriuretic peptide hormones (atrial and brain natriuretic peptides, ANP and BNP). DESIGN--Cross sectional study of left ventricular function in patients two to eight days after acute myocardial infarction. SETTING--Coronary care unit of a teaching hospital. PATIENTS--75 survivors of a recent myocardial infarction aged 40 to 88 with no history of cardiac failure and without cardiogenic shock at the time of entry to the study. MAIN OUTCOME MEASURES--Sensitivities and specificities of the various methods of detecting left ventricular dysfunction were calculated by comparing them with a cross sectional echocardiographic algorithm for LVEF. RESULTS--Clinical impression was poor at identifying LVEF < 40% (sensitivity 46%). Clinical scoring improved this figure somewhat (modified Peel index sensitivity 64%). Qualitative visual assessment echocardiography was a more sensitive method (sensitivity 82%) for detecting LVEF < 40%. Plasma BNP concentration was also a sensitive measure for detecting left ventricular dysfunction (sensitivity 84%) but plasma ANP concentration was much poorer (sensitivity 64%). CONCLUSION--Left ventricular dysfunction is easily and reliably detected by echocardiographic measurement of LVEF and also by a quick qualitative echocardiographic assessment but is likely to be missed by clinical assessment alone. High concentrations of plasma BNP maybe another useful indicator of left ventricular dysfunction, particularly in hospitals where not all patients can be screened by echocardiography or radionuclide ventriculography after myocardial infarction.