Research on energy savings opportunities in university libraries

Purpose

Mechanical systems in library environments are typically designed to run continuously in order to maintain the desired environmental conditions for preservation purposes, often resulting in a high cost in dollars and energy consumption. Altering these conditions through changed HVAC operating schedules is a risk many librarians and institutions are hesitant to take. This study aims to introduce the methodology and early findings of current research into the question of whether energy usage can be significantly reduced in libraries by carefully monitored and risk‐managed shutdowns of air handling units (AHUs) during unoccupied hours in selected spaces without compromising the quality of the preservation environment.

Design/methodology approach

As part of the project, the authors are monitoring up to three air handling units (AHUs) at each of five partner institutions, three of which are university libraries or repositories, as well as the associated collections spaces served by the units.

Findings

Early findings show the potential value of systems shutdowns in various parts of the country, while also identifying regions that are less favorable.

Practical implications

In all cases, the experimentation with and successful implementation of a shutdown schedule, without adversely affecting preservation conditions, was preceded by careful documentation and risk management, as described.

Originality/value

Unlike unilateral HVAC equipment shutdowns and setbacks conducted solely for energy management, with little regard for collections, this risk‐managed and documented approach potentially allows for the reduction of energy usage without placing collections' health at risk.

Primary follicular lymphoma of the duodenum is a distinct mucosal/submucosal variant of follicular lymphoma: a retrospective study of 63 cases

PURPOSE

Small series with limited follow-up have suggested primary follicular lymphoma of the duodenum (FL-D) to be an indolent disease. We report our experience on a large series of patients followed for a median time period of longer than 6 years.

PATIENTS AND METHODS

The study comprised 63 patients with primary FL-D defined as stage I disease. Endoscopy and detailed pathologic work-up was performed at diagnosis and at restaging to monitor the behavior of the neoplastic process.

RESULTS

Histologically, all 63 patients had FL, low grade (1 to 2). Duodenal endosonography demonstrated lesions confined to mucosa/submucosa in 19 of 20 patients. At an overall median follow-up of 77 months (range, 12 to 177 months), only two untreated patients had developed nodal disease, the remaining 61 patients never experienced extrasmall intestinal disease and large cell transformation did not occur at all. Among 24 patients followed by watch and wait strategy, seven showed spontaneous complete regression and 17 had stable disease; radiotherapy resulted in complete regression in all 19 patients; anti-CD20 antibody monotherapy achieved complete regression in four patients and stable disease in one patient. Various chemotherapy protocols in eight patients caused complete regression in all of them, but local relapses occurred in three. No patients required surgery or died of disease.

CONCLUSION

These findings characterize primary FL-D as a remarkably indolent FL variant, which, even left untreated, does not develop tumorous growth, very rarely disseminates (two of 63 patients) and does not transform to high grade disease. A watch and wait approach appears to be the most sensible strategy.

Relevance of correction for rotational targeting error in functional neurosurgery

OBJECTIVE

A prospective study is presented on the amount of targeting error that is due to rotational deviations between the atlas and the stereotactic coordinate system.

MATERIALS AND METHODS

We investigated 14 volunteers with a stereotactic frame fixed to their heads by tight adhesive bands. Sagittal, coronal and axial T2-weighted MRI scans, as well as MPRage sequences, were performed. The anterior and posterior commissures and one additional point on the midline (the septum pellucidum) were determined on the axial T2-weighted images. Bilateral atlas coordinates for the subthalamic nucleus (STN), globus pallidus pars interna (GPi) and nucleus ventralis intermedius (Vim) were transformed to stereotactic frame coordinates, either without correction or by 2-point or 3-point correction. A total of 896 coordinates (x, y, z for the STN, GPi and Vim in both hemispheres) were calculated.

RESULTS

Although the mean differences between the two algorithms (0.24 +/- standard deviation of 0.33 mm) were within the range of system-immanent inaccuracies in MRI-guided stereotaxy, deviations of up to 2.8 mm occurred. No significant correlation was found regarding the amount of rotational angle and the differences in x-, y-, or z-coordinates when 2-point and 3-point transformations were compared.

CONCLUSIONS

The reliability of meticulous trajectory planning might be compromised significantly by using only 2-point-based correction or no calculations at all.

Assessment of radiation exposure on a dual-source computed tomography-scanner performing coronary computed tomography-angiography

OBJECTIVE

The radiation exposure of a dual-source-64-channel multi-detector-computed-tomography-scanner (Somatom-Defintion, Siemens, Germany) was assessed in a phantom-study performing coronary-CT-angiography (CTCA) in comparison to patients' data randomly selected from routine scanning.

METHODS

240 CT-acquisitions of a computed tomography dose index (CTDI)-phantom (PTW, Freiburg, Germany) were performed using a synthetically generated Electrocardiography (ECG)-signal with variable heart rates (30-180 beats per minute (bpm)). 120 measurements were acquired using continuous tube-output; 120 measurements were performed using ECG-synchronized tube-modulation. The pulsing window was set at minimum duration at 65% of the cardiac cycle between 30 and 75 bpm. From 90-180 bpm the pulsing window was set at 30-70% of the cardiac cycle. Automated pitch adaptation was always used. A comparison between phantom CTDI and two patient groups' CTDI corresponding to the two pulsing groups was performed.

RESULTS

Without ECG-tube-modulation CDTI-values were affected by heart-rate-changes resulting in 85.7 mGray (mGy) at 30 and 45 bpm, 65.5 mGy/60 bpm, 54.7 mGy/75 bpm, 46.5 mGy/90 bpm, 34.2 mGy/120 bpm, 27.0 mGy/150 bpm and 22.1 mGy/180 bpm equal to effective doses between 14.5 mSievert (mSv) at 30/45 bpm and 3.6 mSv at 180 bpm. Using ECG-tube-modulation these CTDI-values resulted: 32.6 mGy/30 bpm, 36.6 mGy/45 bpm, 31.4 mGy/60 bpm, 26.8 mGy/75 bpm, 23.7 mGy/90 bpm, 19.4 mGy/120 bpm, 17.2 mGy/150 bpm and 15.6 mGy/180 bpm equal to effective doses between 5.5 mSv at 30 bpm and 2.6 mSv at 180 bpm. Significant CTDI-differences were found between patients with lower/moderate and higher heart rates in comparison to the phantom CTDI-results.

CONCLUSIONS

Dual source CTCA is particularly dose efficient at high heart rates when automated pitch adaptation, especially in combination with ECG-based tube-modulation is used. However in clinical routine scanning for patients with higher heart rates and corresponding enlarged pulsing window a significant different dose resulted.

Chronische Lungenembolie – Radiologische Bildmorphologie und Differenzialdiagnose

In chronic pulmonary embolism branches of the pulmonary arterial tree remain partially or totally occluded. This may lead to pulmonary hypertension with the development of right ventricular hypertrophy as well as structural changes of pulmonary arteries. Imaging of chronic pulmonary embolism should prove vessel occlusions (pulmonary angiography, MSCT, MRI) and reduction of regional lung perfusion (lung scanning, MSCT, MRI). According to current guidelines ventilation-perfusion lung scanning and pulmonary angiography are still recommended as the methods of choice. MSCT and MRI provide technical alternatives which are helpful in differential diagnosis versus other types of pulmonary hypertension. In spite of medical and surgical measures (in rare cases pulmonary thromboendarterectomy) the prognosis of chronic pulmonary embolism remains unfavourable.

Beam hardening artefacts occur in dental implant scans with the NewTom cone beam CT but not with the dental 4-row multidetector CT

OBJECTIVES

The aim of this study was to examine beam hardening artefacts of the NewTom 9000 cone-beam computed tomography (CBCT) device compared with the Philips MX 8000 (4-row multidetector CT (MDCT)).

METHODS

We modified a SawBone skull to become a standardized model for our study. The skull was used for scans with the NewTom 9000 CBCT device and a standard dental multi-detector CT (MDCT) at a comparable reconstruction resolution with a standard Straumann ITI 4.1 mm implant in four implant positions in the maxilla (first permanent premolar in the right maxilla region, second permanent molar in the right maxilla region, first permanent premolar in the left maxilla region and second permanent molar in the left maxilla region). Results were compared with construction data of the dental implant. An image quality assessment of the images from both devices was performed with four experienced physicians and statistically analysed with the two-tailed Wilcoxon test.

RESULTS

Scans with the NewTom 9000 CBCT showed strong beam hardening artefacts in the form of a radiation beam shadow in all reconstructions compared with the MDCT. These imaging artefacts became stronger with greater distance from the centre of the scanned volume. These differences in the imaging quality were proved as significant in a quality evaluation by four experienced physicians (P<0.05).

CONCLUSIONS

Visual spatial resolution of the NewTom 9000 CBCT was less accurate than the Philips MX 8000 MDCT in the imaging of metallic dental implants.

Clinical evaluation of a computer-aided diagnosis (CAD) prototype for the detection of pulmonary embolism

RATIONALE AND OBJECTIVES

To evaluate the performance of a prototype computer-aided diagnosis (CAD) tool using artificial intelligence techniques for the detection of pulmonary embolism (PE) and the possible benefit for general radiologists.

MATERIALS AND METHODS

Forty multidetector row computed tomography datasets (16/64- channel scanner) using 100 kVp, 100 mAs effective/slice, and 1-mm axial reformats in a low-frequency reconstruction kernel were evaluated. A total of 80 mL iodinated contrast material was injected at a flow rate of 5 mL/seconds. Primarily, six general radiologists marked any PE using a commercially available lung evaluation software with simultaneous, automatic processing by CAD in the background. An expert panel consisting of two chest radiologists analyzed all PE marks from the readers and CAD, also searching for additional finding primarily missed by both, forming the ground truth.

RESULTS

The ground truth consisted of 212 emboli. Of these, 65 (31%) were centrally and 147 (69%) were peripherally located. The readers detected 157/212 emboli (74%) leading to a sensitivity of 97% (63/65) for central and 70% (103/147) for peripheral emboli with 9 false-positive findings. CAD detected 168/212 emboli (79%), reaching a sensitivity of 74% for central (48/65) and 82%(120/147) for peripheral emboli. A total of 154 CAD candidates were considered as false positives, yielding an average of 3.85 false positives/case.

CONCLUSIONS

The CAD software showed a sensitivity comparable to that of the general radiologists, but with more false positives. CAD detection of findings incremental to the radiologists suggests benefit when used as a second reader. Future versions of CAD have the potential to further increase clinical benefit by improving sensitivity and reducing false marks.

A randomized multi-center phase II trial of the angiogenesis inhibitor Cilengitide (EMD 121974) and gemcitabine compared with gemcitabine alone in advanced unresectable pancreatic cancer

Background

Anti-angiogenic treatment is believed to have at least cystostatic effects in highly vascularized tumours like pancreatic cancer. In this study, the treatment effects of the angiogenesis inhibitor Cilengitide and gemcitabine were compared with gemcitabine alone in patients with advanced unresectable pancreatic cancer.

Methods

A multi-national, open-label, controlled, randomized, parallel-group, phase II pilot study was conducted in 20 centers in 7 countries. Cilengitide was administered at 600 mg/m² twice weekly for 4 weeks per cycle and gemcitabine at 1000 mg/m² for 3 weeks followed by a week of rest per cycle. The planned treatment period was 6 four-week cycles. The primary endpoint of the study was overall survival and the secondary endpoints were progression-free survival (PFS), response rate, quality of life (QoL), effects on biological markers of disease (CA 19.9) and angiogenesis (vascular endothelial growth factor and basic fibroblast growth factor), and safety. An ancillary study investigated the pharmacokinetics of both drugs in a subset of patients.

Results

Eighty-nine patients were randomized. The median overall survival was 6.7 months for Cilengitide and gemcitabine and 7.7 months for gemcitabine alone. The median PFS times were 3.6 months and 3.8 months, respectively. The overall response rates were 17% and 14%, and the tumor growth control rates were 54% and 56%, respectively. Changes in the levels of CA 19.9 went in line with the clinical course of the disease, but no apparent relationships were seen with the biological markers of angiogenesis. QoL and safety evaluations were comparable between treatment groups. Pharmacokinetic studies showed no influence of gemcitabine on the pharmacokinetic parameters of Cilengitide and vice versa.

Conclusion

There were no clinically important differences observed regarding efficacy, safety and QoL between the groups. The observations lay in the range of other clinical studies in this setting. The combination regimen was well tolerated with no adverse effects on the safety, tolerability and pharmacokinetics of either agent.

Pulmonary abnormalities in immunocompromised patients: comparative detection with parallel acquisition MR imaging and thin-section helical CT

PURPOSE

To compare parallel acquisition magnetic resonance (MR) imaging with thin-section helical computed tomography (CT) for depiction of pulmonary abnormalities suggestive of pneumonia in immunocompromised patients.

MATERIALS AND METHODS

The institutional review board approved this study; prior consent was obtained. Thirty consecutive neutropenic patients (10 women, 20 men; mean age, 51 years +/- 15 [standard deviation]; range, 25-75 years) with fever of unknown origin or clinical signs and symptoms of lung infection were examined with breath-hold single-shot half-Fourier turbo spin-echo MR imaging. To reduce image blurring and increase MR signal in the lungs, the echo time was shortened with generalized autocalibrating partially parallel acquisition (GRAPPA). Patients underwent thoracic CT (four detector rows and 1-mm section thickness [4 x 1 mm]; pitch, 6) as reference standard. Pulmonary abnormalities (ill-defined nodules, ground-glass opacity areas, and consolidation), their location and distribution, and lesion characteristics were analyzed at MR imaging by three readers, blinded to results of CT, in consensus. Frequencies were calculated for each feature; paired Wilcoxon rank sum test was used to examine whether differences between CT and MR imaging features were statistically significant (alpha < .05). Bonferroni adjustments were performed. Overall sensitivity, specificity, and positive and negative predictive values were determined.

RESULTS

Twenty-two patients had pulmonary abnormalities at CT. In 21 (95%) patients, pneumonia was correctly diagnosed with MR imaging. One false-negative finding occurred in a patient with ill-defined nodules smaller than 1 cm at CT. One false-positive finding with MR imaging was the result of blurring and respiratory artifacts (sensitivity, 95%; specificity, 88%; positive predictive value, 95%; negative predictive value, 88%). There was no significant difference in lesion location and distribution.

CONCLUSION

With parallel imaging (GRAPPA technique) and fast MR imaging, detection of pulmonary abnormalities is almost as good as with CT. MR imaging has a slight disadvantage in its lower capability to assist in characterization of specific internal features, such as cavitations.

Nachweis von pneumonischen Infiltraten mit der MRT

Magnetic resonance imaging (MRI) of the lung is challenging because of substantial drawbacks. However, lung pathologies that are associated with increased attenuation values in CT enhance visualization in MRI: proton density is increased and tissue-air interfaces, resulting in susceptibility artifacts, are reduced in pneumonia, pneumonitis, edema, and carcinoma. On the other hand, many lung diseases result in shortness of breath, so that patients cannot hold their breath for long periods. Therefore, fast imaging techniques are required which should also allow for high spatial resolution so that small lesions can be detected. Calcifications and air pockets within lesions are not readily recognized with MRI. Thin section CT is standard for the diagnosis of pneumonia. With parallel imaging techniques, MRI examination of the lungs can be performed with short periods of breath holding, which allow for sub-centimeter resolution in the z-axis. Especially for follow-up examinations in immunocompromised patients and, in some instances, for the staging of malignant diseases (malignant pleural mesothelioma, lung cancer, respectively), MRI is very promising and may contribute to a decrease in the radiation exposure of the patients.

Dose reduction in multidetector CT of the urinary tract. Studies in a phantom model

A novel ureter phantom was developed for investigations of image quality and dose in CT urography. The ureter phantom consisted of a water box (14 cm x 32 cm x 42 cm) with five parallel plastic tubes (diameter 2.7 mm) filled with different concentrations of contrast media (1.88-30 mg iodine/ml). CT density of the tubes and noise of the surrounding water were determined using two multidetector scanners (Philips MX8000 with four rows, Siemens Sensation 16 with 16 rows) with varying tube current-time product (15-100 mAs per slice), voltage (90 kV, 100 kV, 120 kV), pitch (0.875-1.75), and slice thickness (1 mm, 2 mm, 3.2 mm). Contrast-to-noise ratio as a parameter of image quality was correlated with dose (CTDI) and was compared with image evaluation by two radiologists. The CT densities of different concentrations of contrast media and contrast-to-noise ratio were significantly higher when low voltages (90 kV versus 120 kV, 100 kV versus 120 kV) were applied. Smaller slice thickness (1 mm versus 2 mm) did not change CT density but decreased contrast-to-noise ratio due to increased noise. Contrast phantom studies showed favourable effects of low tube voltage on image quality in the low dose range. This may facilitate substantial dose reduction in CT urography.

High-resolution whole-body magnetic resonance image tumor staging with the use of parallel imaging versus dual-modality positron emission tomography-computed tomography: experience on a 32-channel system

OBJECTIVE

The objective of this study was to compare the accuracy in staging of various malignant tumors with whole-body magnetic resonance imaging (WB-MRI) using parallel imaging (PAT) and positron emission tomography-computed tomography (PET-CT).

MATERIALS AND METHODS

In a prospective study, 41 patients withoncologic diseases underwent [F]-fluoro-2-deoxy-D-glucose PET-CT for tumor staging and WB-MRI on a 32-channel-scanner with the use of PAT. Coronal T1w and STIR sequences at 5 body levels, axial HASTE imaging of the lung, and contrast-enhanced T1w sequences of the liver, brain, and abdomen were performed. TNM stage was assessed for both modalities in a separate consensus reading using histologic results and radiologic follow up within 6 months as the standard of reference.

RESULTS

Three primary and 4 recurrent tumors were detected; one recurrent tumor was missed with WB-MRI. Sixty benign and 60 malignant lymph nodes were detected with a sensitivity of 98% and specificity of 83% for PET-CT and 80%/75% for WB-MRI, respectively. One hundred ninety-one malignant and 77 benign distant lesions were detected with a sensitivity/specificity of 82% for PET-CT and 96%/82% for WB-MRI. Accuracy for correct TNM staging was 96% for PET-CT and 91% for WB-MRI.

CONCLUSION

WB-MRI and PET-CT are reliable imaging modalities for tumor staging. WB-MRI is highly sensitive in detecting distant metastases; PET-CT is superior in lymph node staging. PAT makes high-resolution WB-MRI feasible within less than 1 hour.

Computer-aided diagnosis as a second reader: spectrum of findings in CT studies of the chest interpreted as normal

STUDY OBJECTIVES

To assess the performance of an automated computer-aided detection (CAD) system as a second reader on chest CT studies interpreted as normal at routine clinical interpretation.

DESIGN

Chest CT studies were processed using a prototype CAD system for automated detection of lung lesions. Three experienced radiologists analyzed each CAD finding and confirmed or dismissed the marked image features as lung lesions. Noncalcified, focal lung lesions were classified according to size as being of high (> or = 10 mm), intermediate (5 to 9 mm), or low (< or = 4 mm) significance.

SETTING

Two sub-specialized academic tertiary referral centers in the United States and Germany.

PATIENTS

Chest CT studies were performed in 100 patients, with results initially reported as normal at clinical double reading. Indications for chest CT were suspected pulmonary embolism (PE) [n = 33], lung cancer screening in a high-risk population (n = 28), or follow-up for a cancer history (n = 39).

INTERVENTIONS

Reevaluation of all chest CT studies for focal lung lesions with the CAD system as a second reader.

MEASUREMENTS

Prevalence and spectrum of lung lesions missed at routine clinical interpretation but found by the CAD system.

RESULTS

In 33% (33 of 100 patients), CAD detected significant lung lesions that were not previously reported. Fifty-three significant lesions were detected (mean, 1.6 lesions per case), of which 5 lesions (9.4%) were of high significance, 21 lesions (39.6%) were of intermediate significance, and 27 lesions (50.9%) were of low significance. In the PE group, the lung cancer screening group, and the group with a cancer history, four patients (12.1%), six patients (21.4%), and nine patients (23.1%), respectively, had focal lung lesions of high and/or intermediate significance. The false-positive rate of the CAD system was an average of 1.25 per case (range, 0 to 11).

CONCLUSIONS

Significant lung lesions are frequently missed at routine clinical interpretation of chest CT studies but may be detected if CAD is used as an additional reader.

18F-FDG PET/CT for staging of penile cancer

The value of PET or PET/CT with (18)F-FDG for the staging of penile cancer has yet to be determined. The objective of this study was to investigate the pattern of (18)F-FDG uptake in the primary malignancy and its metastases and to determine the diagnostic value of (18)F-FDG PET/CT in the staging and restaging of penile cancer.

METHODS

Thirteen patients (mean +/- SD age, 64 +/- 14.0 y) with suspected penile cancer or suspected recurrent disease were examined with a Gemini PET/CT system (200 MBq of (18)F-FDG). The reference standard was based on histopathologic findings obtained at biopsy or during surgery.

RESULTS

Both the primary tumor and regional lymph node metastases exhibited a pattern of (18)F-FDG uptake typical for malignancy. Sensitivity in the detection of primary lesions was 75% (6/8), and specificity was 75% (3/4). On a per-patient basis, sensitivity in the detection of lymph node metastases was 80% (4/5), and specificity was 100% (8/8). On a nodal-group basis, PET/CT showed a sensitivity of 89% (8/9) in the detection of metastases in the superficial inguinal lymph node basins and a sensitivity of 100% (7/7) in the deep inguinal and obturator lymph node basins. The mean +/- SD maximum standardized uptake value for the 8 primary lesions was 5.3 +/- 3.7, and that for the 16 lymph node metastases was 4.6 +/- 2.0.

CONCLUSION

According to our results, the main indication for (18)F-FDG PET in the primary staging or follow-up of penile cancer patients may be the prognostically crucial search for lymph node metastases. With the use of a PET/CT unit, the additional information provided by CT may be especially useful for planning surgery. Implementing (18)F-FDG PET and PET/CT in future staging algorithms may lead to a more precise and stage-appropriate therapeutic strategy. Furthermore, invasive procedures with a high morbidity rate, such as general bilateral lymphadenectomy, may be avoided.

Approaches to CT perfusion imaging in pulmonary embolism

Computed tomography (CT) has become an increasingly accepted technique and is the method of choice for direct visualization of pulmonary emboli (PE). The quantitative assessment of tissue perfusion may yield more important information for patient management than the direct visualization of emboli by CT alone. Several attempts have been made to measure pulmonary blood flow by administration of intravenous contrast material. In this article, various experimental CT approaches for visualization and quantification of pulmonary perfusion are discussed. Ideally, CT will be able to provide both structural and functional information. Simple measurement of lung density before and after intravenous contrast delivery has been performed with single-slice CT technology using region-of-interest methodology. For electron-beam CT, a repeated data acquisition on a 7.6-cm lung volume has proven to be technically feasible. Using such dynamic scanning, reduced blood flow was observed in occluded lung segments. Color-encoded parenchymal density distribution in the axial, coronal, and sagittal planes was derived from thin collimation data sets using four-row multi-slice spiral CT (MSCT). Initial animal data from 16-slice MSCT offer a real CT-subtraction technique of the entire chest for the first time.