Does positron emission tomography data acquisition impact simultaneous diffusion-weighted imaging in a whole-body PET/MRI system?

Objectives

The purpose of this study was to test whether the acquisition of positron emission tomography (PET) does interfere with simultaneous diffusion weighted imaging (DWI) in an integrated whole-body PET/MRI system.

Material and methods

Fourteen consecutive oncological patients (9 men, 5 women; age 54 ± 13 years ([mean ± standard deviation]) scheduled for routine [¹⁸F]-FDG PET/CT were prospectively enrolled. For DWI, an echo planar imaging (EPI) sequence (b = 0–500–1000 s/mm²) was acquired twice on an integrated whole-body 3 T PET/MRI system in each patient; first with simultaneous PET acquisition and a second time with the PET component switched off. The apparent diffusion coefficient (ADC) and the signal-to-noise ratio at b = 1000 s/mm² (SNR) of the myocardium, paraspinal muscle, liver, spleen, renal cortex and tumor tissue (if present) were measured. In addition, the coefficient of variation (CV) of ADC values was calculated. Student's t-test for paired samples was performed to test for differences of the mean ADC, ADC CV and SNR between DWI with and without simultaneous PET acquisition.

Results

There were no significant differences of the ADC [(mean ± standard deviation)] between the DWI acquisitions with and without simultaneous PET acquisition for the myocardium (2572 ± 441 × 10⁻⁶ mm²/s and 2586 ± 376 × 10⁻⁶ mm²/s, respectively) (P = 0.817), paraspinal muscle (1279 ± 254 × 10⁻⁶ mm²/s vs. 1219 ± 181 × 10⁻⁶ mm²/s) (P = 0.318), liver (1245 ± 158 × 10⁻⁶ mm²/s vs. 1254 ± 171 × 10⁻⁶ mm²/s) (P = 0.848), spleen (980 ± 122 × 10⁻⁶ mm²/s vs. 1000 ± 187 × 10⁻⁶ mm²/s) (P = 0.676) and renal cortex (1951 ± 226 × 10⁻⁶ mm²/s vs. 1930 ± 273 × 10⁻⁶ mm²/s) (P = 0.730). Mean ADC of lymph node metastases (n = 6) did not differ between with PET acquisition (853 ± 174 × 10⁻⁶ mm²/s) and without simultaneous PET (865 ± 170 × 10⁻⁶ mm²/s) (P = 0.675). There were no significant differences between the CV of ADC values or the SNR values measured in DWI datasets that were acquired with or without simultaneous PET for any evaluated organ site.

Conclusion

The simultaneous acquisition of DWI and PET on an integrated PET/MRI system does not impact ADC quantification of normal and tumor tissue and does not alter SNR. This knowledge provides a basis for the use of simultaneous multiparametric PET/MRI comprising DWI in diagnostic imaging and quantitative tumor therapy monitoring using repeated ADC measurements.     

The use of an electric freezer in human semen banking

The use of an electric freezer for cryostorage of human semen is described. A simple method for semen freezing in liquid nitrogen after dilution with 7.5% glycerol was used. Thawing for quality analysis revealed only a small decrease (10%) in post-thaw sperm motility (59 +/- 1.4 vs. 53 +/- 1.8%; mean +/- SE, n = 12, P less than 10(-5)) and 14% in post-thaw sperm vitality (85.0 +/- 1.3 vs. 72.9 +/- 1.8%). After the freezing process, the samples, three of each donor, were cryopreserved in a regular electric freezer which maintained temperatures in the range of -85 degrees C (+/- 2 degrees C). The samples were stored for 1 week, 2 and 6 months, thawed and then assayed for motility and vitality. No effect of storage was found for a period up to 2 months. An additional decrease of 17.2% in sperm motility and 18% in sperm vitality were noted only after 6 months of preservation. The final motility and vitality rates of these sperm samples were 44 +/- 2.4 and 60 +/- 3.0%, respectively. According to these results, in cases of sperm storage for limited periods, it is recommended to cryopreserve human semen by the use of a combination of freezing in liquid nitrogen and storage of the samples in an electric freezer at -85 degrees C.     

Pethidine in emergency departments: promoting evidence-based prescribing

OBJECTIVE: To reduce pethidine prescribing in hospital emergency departments (EDs). DESIGN: Multi-centre drug use evaluation (DUE) process. SETTING AND PARTICIPANTS: Emergency departments in 23 public hospitals (22 in New South Wales, 1 in Victoria) from 1 September 2002 to 31 August 2003. Participating hospitals included seven principal referral hospitals, six major non-teaching hospitals and 10 district or community hospitals. Data for comparison were collected from 12 non-participating hospitals. INTERVENTIONS: Hospital coordinators at each participating hospital were provided with support to implement a range of prescribing interventions in their ED in each of three DUE cycles. Interventions included educational materials (guidelines, posters, prescribing reminders), audit and feedback, and small-group discussions. Three audits of pethidine prescribing were undertaken. Prescribing was compared with evidence-based guidelines and non-concordance identified. MAIN OUTCOME MEASURES: Number of dosage units of parenteral analgesics issued to the ED from each hospital's pharmacy department was recorded monthly and aggregated in 3-month periods. RESULTS: In the 12 months between the preintervention period and the equivalent post-intervention period, pethidine use decreased by 62% in project hospitals (4669 to 1793 units) and 56% in control hospitals (1476 to 648 units). Six months after project completion there was a significantly greater reduction from baseline in participating hospitals (71%; 4669 to 1348 units) compared with non-participating hospitals (64%; 1476 to 532 units; P < 0.001). There was a concurrent increase in use of both morphine and tramadol. CONCLUSION: There was a sustained reduction in pethidine use during the study period, which may indicate successful promotion of safer analgesic prescribing. It is not clear whether changes were a result of collaborative DUE methods or other factors.     

Mitochondrial pro-apoptotic ARTS protein is lost in the majority of acute lymphoblastic leukemia patients

Acquired resistance towards apoptosis is the hallmark of most if not all types of cancer. We have previously identified and characterized ARTS, a broadly expressed protein localized to mitochondria. ARTS was initially shown to mediate TGF-beta induced apoptosis. Recently, we have found that high levels of ARTS induce apoptosis without additional pro-apoptotic stimuli. Further, ARTS promotes apoptosis in response to a wide variety of pro-apoptotic stimuli. Here, we report that the expression of ARTS is lost in all lymphoblasts of more than 70% of childhood acute lymphoblastic leukemia (ALL) patients. The loss of ARTS is specific, as the related non-apoptotic protein H5, bearing 83% identity to ARTS, is unaffected. During remission, ARTS expression is detected again in almost all patients. Two leukemic cell lines, ALL-1 and HL-60 lacking ARTS, were resistant to apoptotic induction by ara-C. Transfection of ARTS into these cells restored their ability to undergo apoptosis in response to this chemotherapeutic agent. We found that methylation process contributes to the loss of ARTS expression. We conclude that the loss of ARTS may provide a selective advantage for cells to escape apoptosis thereby contributing to their transformation to malignant lymphoblasts. We therefore propose that ARTS can function as a tumor suppressor protein in childhood ALL.     

Stitch removal from hair-bearing areas: a simple method

A simple method to ease the removal of stitches in hair-bearing areas is presented. The method consists of applying a depilatory cream to remove the masking hair.     

The effect of music relaxation versus progressive muscular relaxation on insomnia in older people and their relationship to personality traits

A large percentage of older people suffer from chronic insomnia, affecting many aspects of life quality and well-being. Although insomnia is most often treated with medication, a growing number of studies demonstrate the efficiency of various relaxation techniques. The present study had three aims: first, to compare two relaxation techniques--music relaxation and progressive muscular relaxation--on various objective and subjective measures of sleep quality; second, to examine the effect of these techniques on anxiety and depression; and finally, to explore possible relationships between the efficiency of both techniques and personality variables. Fifteen older adults took part in the study. Following one week of base-line measurements of sleep quality, participants followed one week of music relaxation and one week of progressive muscular relaxation before going to sleep. Order of relaxation techniques was controlled. Results show music relaxation was more efficient in improving sleep. Sleep efficiency was higher after music relaxation than after progressive muscular relaxation. Moreover, anxiety was lower after music relaxation. Progressive muscular relaxation was related to deterioration of sleep quality on subjective measures. Beyond differences between the relaxation techniques, extraverts seemed to benefit more from both music and progressive muscular relaxation. The advantage of non-pharmacological means to treat insomnia, and the importance of taking individual differences into account are discussed.     

Impact of self-assembly properties on antibacterial activity of short acyl-lysine oligomers

We investigated both the structural and functional consequences of modifying the hydrophobic, lipopeptide-mimetic oligo-acyl-lysine (OAK) N(alpha)-hexadecanoyl-l-lysyl-l-lysyl-aminododecanoyl-l-lysyl-amide (c(16)KKc(12)K) to its unsaturated analog hexadecenoyl-KKc(12)K [c(16(omega7))KKc(12)K]. Despite similar tendencies for self-assembly in solution (critical aggregation concentrations, approximately 10 muM), the analogous OAKs displayed dissimilar antibacterial properties (e.g., bactericidal kinetics taking minutes versus hours). Diverse experimental evidence provided insight into these discrepancies: whereas c(16(omega7))KKc(12)K created wiry interconnected nanofiber networks, c(16)KKc(12)K formed both wider and stiffer fibers which displayed distinct binding properties to phospholipid membranes. Unsaturation also shifted their gel-to-liquid transition temperatures and altered their light-scattering properties, suggesting the disassembly of c(16(omega7))KKc(12)K in the presence of bacteria. Collectively, the data indicated that the higher efficiency in interfering with bacterial viability emanated from a wobbly packing imposed by a single double bond. This suggests that similar strategies might improve hydrophobic OAKs and related lipopeptide antibiotics.