Radiation reduction and faster acquisition times with SPECT gated blood pool scans using a high-efficiency cardiac SPECT camera.

BACKGROUND: Planar gated blood pool scans are an established method for the evaluation of left ventricular ejection fraction (LVEF) but the camera technology used for these studies has not significantly changed in decades. The purpose of this study was to determine the diagnostic accuracy of new high-efficiency SPECT gated blood pool scans compared to traditional scans and determine if they can be performed with lower radiation doses or faster acquisition times. METHODS: Patients undergoing a planar gated blood pool scan on a Na-I SPECT camera who consented to participate were subsequently imaged for 5 minutes in "List Mode" using a high-efficiency SPECT camera. LVEF was calculated for both the planar study and at 1, 2, 3, 4, and 5 minutes of acquisition on the high-efficiency camera. Counts acquired in the field of view, counts in the cardiac blood pool and LVEF were compared. RESULTS: A total of 46 patients were analyzed (48% male, mean age 55 years, and BMI 27.6 kg/m(2)) who received an average Tc-99m dose of 20.3 mCi (5.3 mSv), 17 (37%) with abnormal LVEF's. The Na-I camera averaged 24,514 counts/min/mCi in the field of view and 8662 counts/min/mCi in the cardiac blood pool while the high-efficiency camera averaged 65,219 counts/min/mCi and 41,427 counts/min/mCi, respectively. Compared to the planar calculation of LVEF, 1-minute SPECT LVEF was on average 8.6 ± 10.7 higher, 2 minutes 3.5 ± 7.6 higher, 3 minutes 2.9 ± 8.5 higher, 4 minutes 2.5 ± 7.0 higher, and 5 minutes 1.1 ± 6.2 higher. Good correlation was seen between the SPECT LVEF's and the planar LVEF's across all acquisition times with correlation coefficients of 0.74-0.93. CONCLUSIONS: High-efficiency SPECT technology can reduce radiation exposure to patients during gated blood pool imaging or decrease acquisition time while maintaining diagnostic accuracy. Based on the improved count sensitivity with high-efficiency SPECT, a 50% reduction in injected activity may be achievable while maintaining short imaging times of 5 minutes, with further reduction possible at longer imaging times.

Reduction in occupational and patient radiation exposure from myocardial perfusion imaging: impact of stress-only imaging and high-efficiency SPECT camera technology.

UNLABELLED: Recently introduced high-efficiency SPECT cameras have demonstrated the ability to reduce radiation exposure to patients undergoing myocardial perfusion imaging studies, especially when combined with stress-only imaging protocols. To date there have been no relevant studies examining the reduced occupational radiation exposure to medical staff. We sought to determine whether changes in stress myocardial perfusion imaging protocols and camera technology can reduce the occupational radiation exposure to the staff of a nuclear cardiology laboratory. METHODS: Monthly radiation dosimeter readings from 4 nuclear technologists, 4 nurses, and 2 administrative employees were analyzed from two 12-mo periods: October 2007-September 2008 (period 1), before the use of high-efficiency SPECT, and October 2010-September 2011 (period 2), after high-efficiency SPECT was introduced. The average monthly dose equivalent in millirems (1 mrem = 0.01 mSv) was recorded from personal dosimeters worn on laboratory coats. The total activity of (99m)Tc used per month, mean (99m)Tc administered activity per patient, average number of patients per month, patient time spent in the laboratory, and proportion of stress-only studies were determined. RESULTS: There were 3,539 patients in period 1 and 3,898 in period 2. An approximately 40% reduction in the dose equivalent across all staff members occurred during this time (-16.9 and -16.2 mrem for nuclear technologists and nurses, respectively; P < 0.0001). During period 2, the total activity of (99m)Tc used per month decreased (10,746 vs. 7,174 mCi [1 mCi = 37 MBq], P < 0.0001), as did the mean (99m)Tc administered activity per patient (36.5 vs. 23.8 mCi, P < 0.0001). The percentage of patients having stress-only imaging increased (35% vs. 56%, P < 0.0001), and the total patient time spent in the laboratory decreased. Radiation dose equivalent levels were reduced in period 2 to 1%-7% of the allowed annual occupational dose equivalent. The combination of the use of high-efficiency SPECT technology and stress-only protocols resulted in a 34.7% reduction in mean total (99m)Tc administered activity between time periods, with camera technology being responsible for 39.2% of the reduction and stress-only protocols for 60.8%. CONCLUSION: A combination of high-efficiency SPECT technology and selective use of stress-only protocols significantly reduces the occupational radiation dose equivalent to the staff of a nuclear cardiology laboratory.

High-efficiency SPECT MPI: comparison of automated quantification, visual interpretation, and coronary angiography.

BACKGROUND: Recently introduced high-efficiency (HE) SPECT cameras with solid-state CZT detectors have been shown to decrease imaging time and reduce radiation exposure to patients. An automated, computer-derived quantification of HE MPI has been shown to correlate well with coronary angiography on one HE SPECT camera system (D-SPECT), but has not been compared to visual interpretation on any of the HE SPECT platforms. METHODS: Patients undergoing a clinically indicated Tc-99m sestamibi HE SPECT (GE Discovery 530c with supine and prone imaging) study over a 1-year period followed by a coronary angiogram within 2 months were included. Only patients with a history of CABG surgery were excluded. Both MPI studies and coronary angiograms were reinterpreted by blinded readers. One hundred and twenty two very low (risk of CAD < 5%) or low (risk of CAD < 10%) likelihood subjects with normal myocardial perfusion were used to create normal reference limits. Computer-derived quantification of the total perfusion deficit at stress and rest was obtained with QPS software. The visual and automated MPI quantification were compared to coronary angiography (≥70% luminal stenosis) by receiver operating curve (ROC) analysis. RESULTS: Of the 3,111 patients who underwent HE SPECT over a 1-year period, 160 patients qualified for the correlation study (66% male, 52% with a history of CAD). The ROC area under the curve (AUC) was similar for both the automated and the visual interpretations using both supine only and combined supine and prone images (0.69-0.74). Using thresholds determined from sensitivity and specificity curves, the automated reads showed higher specificity (59%-67% vs 27%-60%) and lower sensitivity (71%-72% vs 79%-93%) than the visual reads. By including prone images sensitivity decreased slightly but specificity increased for both. By excluding patients with known CAD and cardiomyopathies, AUC and specificity increased for both techniques (0.72-0.82). The use of a difference score to evaluate ischemic burden resulted in lower sensitivities but higher specificities for both automated and visual quantification. There was good agreement between the visual interpretation and automated quantification in the entire cohort of 160 unselected consecutive patients (r = 0.70-0.81, P < .0001). CONCLUSIONS: Automated and visual quantification of high-efficiency SPECT MPI with the GE Discovery camera provides similar overall diagnostic accuracy when compared to coronary angiography. There was good correlation between the two methods of assessment. Combined supine and prone stress imaging provided the best diagnostic accuracy.

Reduced isotope dose and imaging time with a high-efficiency CZT SPECT camera.

BACKGROUND: In light of recent focus on diagnostic imaging, cardiac SPECT imaging needs to become a shorter test with lower radiation exposure to patients. Recently introduced Cadmium Zinc Telluride (CZT) cameras have the potential to achieve both goals. METHODS: During a 2-month period patients presenting for a Tc-99m sestamibi SPECT MPI study were imaged using a CZT camera using a low-dose rest-stress protocol (5 mCi rest and 15 mCi stress doses). Patients ≥250 lbs or a BMI ≥35 kg/m(2) were excluded. Rest images were processed at 5- and 8-minute acquisition times and stress images at 3- and 5-minute acquisition times. A subset of patients had stress imaging performed using both conventional and CZT SPECT cameras. Image acquisition times and SPECT camera images were compared based on total counts, count rate, image quality, and summed rest and stress scores. Twelve month clinical follow-up was also obtained. RESULTS: 131 patients underwent the study protocol (age 64.9 ± 9.8 years, 54.2% male). There was no significant difference in image quality and mean summed scores between 5- and 8-minute rest images and between 3- and 5-minute stress images. When compared to a conventional SPECT camera in 27 patients, total rest and stress perfusion deficits and calculated LVEF were similar (r = 0.94 and 0.96, respectively). At 12 months there was a benign prognosis in patients with normal perfusion. The effective dose was 5.8 mSv for this protocol which is 49.2% less than conventional Tc-99m studies and 75.7% less than conventional Tl-201/Tc-99m dual isotope studies. CONCLUSIONS: New SPECT camera technology with low isotope dose significantly reduces ionizing radiation exposure and imaging times compared to traditional protocols while maintaining image quality and diagnostic accuracy.

Reduced isotope dose with rapid SPECT MPI imaging: initial experience with a CZT SPECT camera.

BACKGROUND: Cardiac SPECT imaging needs to become shorter and use lower radiation doses to compete with other available noninvasive imaging modalities. Recently introduced cadmium zinc telluride (CZT) SPECT cameras have the potential to achieve both goals, but clinical experience is so far limited. METHODS: Images of all patients undergoing a stress MPI over a 4-month period using a CZT camera (Discovery NM 530c) were reviewed. Patients were divided into three groups based on imaging protocols: low-dose stress-only, high-dose stress-only, and standard dose rest-stress. Low-dose stress-only patients were matched by gender, stressor, and BMI to high-dose stress-only and rest-stress subjects. Stress image quality was graded on a four-point scale by readers blinded to the imaging protocol. Demographics, tracer dose, stress imaging time, and total counts were recorded. RESULTS: Of 717 patients imaged, the mean age was 64.0 years, 50.5% were female, 58.9% underwent exercise stress, and the average BMI was 27.9 kg/m(2). A total of 103 low-dose stress-only patients were matched to controls. Imaging for 5 minutes in low-dose stress-only patients and for 3 minutes in high-dose stress-only and rest-stress patients, resulted in a similar number of total counts. This produced similar image quality in the three groups with a 57% isotope dose reduction in the low-dose stress-only compared to the high-dose stress-only group. CONCLUSION: New SPECT CZT camera technology allows significantly reduced radiation exposure and acquisition time without loss of image quality.

My Ishvara is dead: spiritual care on the fringes.

Human suffering speaks differently to different lived contexts. In this paper, I have taken a metaphoric representation of suffering, Ishvara, from the lived context of a Hindu immigrant woman to show that suffering is experienced and expressed within one's lived context. Further, a dominant narrative from her world is presented to show that the same lived context can be a resource for spiritual care that could reconstruct her world that has fallen apart with a suffering experience. Having argued that suffering is experienced and expressed within one's lived context, and that lived context could be a resource, in this paper I present that spiritual care is an intervention into the predicaments of human suffering and its mandate is to facilitate certain direction and a meaningful order through which experiences and expectations are rejoined. Finally, I observe that spiritual care is an engagement between the lived context where suffering is experienced and the spiritual experience and orientation of the caregiver.

Ameloblastic fibro odontoma.

Ameloblastic fibro odontoma is relatively a rare mixed odontogenic tumor comprising of ameloblastic fibroma and ameloblastic odontoma. This group of lesions represent neoplastic and hamartomatous changes. Data regarding age, sex, and site of occurrence of these lesions have been uniquely described. A case of ameloblastic fibro odontoma in a 17-year-old male involving the left body of the mandible, and its radiographic, clinical symptoms and histological features is described herewith. A conservative surgical approach, including enucleation and mechanical curettage of the surrounding bone was done.