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A Nordic survey of CT doses in hybrid PET/CT and SPECT/CT examinations.

ABSTRACT: BACKGROUND:Computed tomography (CT) scans are routinely performed in positron emission tomography (PET) and single photon emission computed tomography (SPECT) examinations globally, yet few surveys have been conducted to gather national diagnostic reference level (NDRL) data for CT radiation doses in positron emission tomography/computed tomography (PET/CT) and single photon emission computed tomography/computed tomography (SPECT/CT). In this first Nordic-wide study of CT doses in hybrid imaging, Nordic NDRL CT doses are suggested for PET/CT and SPECT/CT examinations specific to the clinical purpose of CT, and the scope for optimisation is evaluated. Data on hybrid imaging CT exposures and clinical purpose of CT were gathered for 5 PET/CT and 8 SPECT/CT examinations via designed booklet. For each included dataset for a given facility and scanner type, the computed tomography dose index by volume (CTDIvol) and dose length product (DLP) was interpolated for a 75-kg person (referred to as CTDIvol,75kg and DLP75kg). Suggested NDRL (75th percentile) and achievable doses (50th percentile) were determined for CTDIvol,75kg and DLP75kg according to clinical purpose of CT. Differences in maximum and minimum doses (derived for a 75-kg patient) between facilities were also calculated for each examination and clinical purpose. RESULTS:Data were processed from 83 scanners from 43 facilities. Data were sufficient to suggest Nordic NDRL CT doses for the following: PET/CT oncology (localisation/characterisation, 15 systems); infection/inflammation (localisation/characterisation, 13 systems); brain (attenuation correction (AC) only, 11 systems); cardiac PET/CT and SPECT/CT (AC only, 30 systems); SPECT/CT lung (localisation/characterisation, 12 systems); bone (localisation/characterisation, 30 systems); and parathyroid (localisation/characterisation, 13 systems). Great variations in dose were seen for all aforementioned examinations. Greatest differences in DLP75kg for each examination, specific to clinical purpose, were as follows: SPECT/CT lung AC only (27.4); PET/CT and SPECT/CT cardiac AC only (19.6); infection/inflammation AC only (18.1); PET/CT brain localisation/characterisation (16.8); SPECT/CT bone localisation/characterisation (10.0); PET/CT oncology AC only (9.0); and SPECT/CT parathyroid localisation/characterisation (7.8). CONCLUSIONS:Suggested Nordic NDRL CT doses are presented according to clinical purpose of CT for PET/CT oncology, infection/inflammation, brain, PET/CT and SPECT/CT cardiac, and SPECT/CT lung, bone, and parathyroid. The large variation in doses suggests great scope for optimisation in all 8 examinations.

SUBMITTER: Bebbington NA

PROVIDER: S-EPMC6915162 | biostudies-literature | 2019 Dec

REPOSITORIES: biostudies-literature

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A Nordic survey of CT doses in hybrid PET/CT and SPECT/CT examinations.

Bebbington Natalie A NA Haddock Bryan T BT Bertilsson Henrik H Hippeläinen Eero E Husby Ellen M EM Tunninen Virpi I VI Söderberg Marcus M

EJNMMI physics 20191216 1

<h4>Background</h4>Computed tomography (CT) scans are routinely performed in positron emission tomography (PET) and single photon emission computed tomography (SPECT) examinations globally, yet few surveys have been conducted to gather national diagnostic reference level (NDRL) data for CT radiation doses in positron emission tomography/computed tomography (PET/CT) and single photon emission computed tomography/computed tomography (SPECT/CT). In this first Nordic-wide study of CT doses in hybrid ...[more]

PMID: 31845047

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Project description:ImportanceAt present, the choice of noninvasive testing for a diagnosis of significant coronary artery disease (CAD) is ambiguous, but nuclear myocardial perfusion imaging with single-photon emission tomography (SPECT) or positron emission tomography (PET) and coronary computed tomography angiography (CCTA) is predominantly used for this purpose. However, to date, prospective head-to-head studies are lacking regarding the diagnostic accuracy of these imaging modalities. Furthermore, the combination of anatomical and functional assessments configuring a hybrid approach may yield improved accuracy.ObjectivesTo establish the diagnostic accuracy of CCTA, SPECT, and PET and explore the incremental value of hybrid imaging compared with fractional flow reserve.Design, setting, and participantsA prospective clinical study involving 208 patients with suspected CAD who underwent CCTA, technetium 99m/tetrofosmin-labeled SPECT, and [15O]H2O PET with examination of all coronary arteries by fractional flow reserve was performed from January 23, 2012, to October 25, 2014. Scans were interpreted by core laboratories on an intention-to-diagnose basis. Hybrid images were generated in case of abnormal noninvasive anatomical or functional test results.Main outcomes and measuresHemodynamically significant stenosis in at least 1 coronary artery as indicated by a fractional flow reserve of 0.80 or less and relative diagnostic accuracy of SPECT, PET, and CCTA in detecting hemodynamically significant CAD.ResultsOf the 208 patients in the study (76 women and 132 men; mean [SD] age, 58 [9] years), 92 (44.2%) had significant CAD (fractional flow reserve ≤0.80). Sensitivity was 90% (95% CI, 82%-95%) for CCTA, 57% (95% CI, 46%-67%) for SPECT, and 87% (95% CI, 78%-93%) for PET, whereas specificity was 60% (95% CI, 51%-69%) for CCTA, 94% (95% CI, 88%-98%) for SPECT, and 84% (95% CI, 75%-89%) for PET. Single-photon emission tomography was found to be noninferior to PET in terms of specificity (P < .001) but not in terms of sensitivity (P > .99) using the predefined absolute margin of 10%. Diagnostic accuracy was highest for PET (85%; 95% CI, 80%-90%) compared with that of CCTA (74%; 95% CI, 67%-79%; P = .003) and SPECT (77%; 95% CI, 71%-83%; P = .02). Diagnostic accuracy was not enhanced by either hybrid SPECT and CCTA (76%; 95% CI, 70%-82%; P = .75) or by PET and CCTA (84%; 95% CI, 79%-89%; P = .82), but resulted in an increase in specificity (P = .004) at the cost of a decrease in sensitivity (P = .001).Conclusions and relevanceThis controlled clinical head-to-head comparative study revealed PET to exhibit the highest accuracy for diagnosis of myocardial ischemia. Furthermore, a combined anatomical and functional assessment does not add incremental diagnostic value but guides clinical decision-making in an unsalutary fashion.

Project description:OBJECTIVE:The perceived burden of diagnostic tests by patients during the assessment of esophageal cancer warrants attention with the current increase in repeated imaging for purposes of disease monitoring during and after treatment. The purpose of this prospective study was to evaluate the experienced burden associated with repeated MRI and positron emission tomography with integrated CT (PET/CT) examinations during neoadjuvant treatment for esophageal cancer from the perspective of the patient. METHODS:In 27 patients receiving neoadjuvant chemoradiotherapy (nCRT) for esophageal cancer MRI and PET/CT examinations were performed before nCRT, during nCRT and before surgery. The experienced burden during repeated MRI and PET/CT examinations was evaluated with a self-report questionnaire addressing discomfort, pain, anxiety and embarrassment, each measured on a 5-point Likert scale (1 = none; up to 5 = very?much). In addition, a comparative assessment was used to rank MRI, PET/CT and baseline endoscopy. RESULTS:All scans were performed without the occurrence of an adverse event. Few patients experienced discomfort (mean score ±SD: 1.9 ± 1.0 for MRI vs 2.0 ± 1.0 for PET/CT, p = 0.586), pain (1.1 ± 0.4 for MRI vs 1.3 ± 0.7 for PET/CT, p = 0.059), anxiety (1.0 ± 0.2 for MRI vs 1.0 ± 0.2 for PET/CT, p = 1.000) and embarrassment (1.0 ± 0 for MRI vs 1.0 ± 0.2 for PET/CT, p = 0.317) during both MRI and PET/CT. Patients preferred MRI over PET/CT (67% vs 22%, respectively, p = 0.023), and MRI over endoscopy (59% vs 19%, respectively, p = 0.027). In the comparison between PET/CT and endoscopy, 59% of patients preferred PET/CT and 26% preferred endoscopy (p = 0.093). CONCLUSION:Repeated imaging with both MRI and PET/CT is generally well-tolerated for the assessment of response to treatment in esophageal cancer patients. Shorter acquisition times and altered body positioning during scanning will likely improve patient experience. ?Advances in knowledge: This paper demonstrates that MRI and PET/CT are generally well-tolerated imaging procedures for the assessment of response to treatment in esophageal cancer patients. When asked to rank different tests, patients preferred MRI over PET/CT and endoscopy.

Project description:For brown adipose tissue (BAT) to be effective at consuming calories, its blood flow must increase enough to provide sufficient fuel to sustain energy expenditure and also transfer the heat created to avoid thermal injury. Here we used a combination of human and rodent models to assess changes in BAT blood flow and glucose utilization.(99m)Tc-methoxyisobutylisonitrile (MIBI) SPECT (n = 7) and SPECT/CT (n = 74) scans done in adult humans for parathyroid imaging were reviewed for uptake in regions consistent with human BAT. Site-directed biopsies of subcutaneous and deep neck fat were obtained for electron microscopy and gene expression profiling. In mice, tissue perfusion was measured with (99m)Tc-MIBI (n = 16) and glucose uptake with (18)F-FDG (n = 16). Animals were kept fasting overnight, anesthetized with pentobarbital, and given intraperitoneally either the ?3-adrenergic receptor agonist CL-316,243, 1 mg/kg (n = 8), or saline (n = 8) followed by radiotracer injection 5 min later. After 120 min, the mice were imaged using SPECT/CT or PET/CT. Vital signs were recorded over 30 min during the imaging. BAT, white adipose tissue (WAT), muscle, liver, and heart were resected, and tissue uptake of both (99m)Tc-MIBI and (18)F-FDG was quantified by percentage injected dose per gram of tissue and normalized to total body weight.In 5.4% of patients (4/74), (99m)Tc-MIBI SPECT/CT showed increased retention in cervical and supraclavicular fat that displayed multilocular lipid droplets, dense capillary investment, and a high concentration of ovoid mitochondria. Expression levels of the tissue-specific uncoupling protein-1 were 180 times higher in BAT than in subcutaneous WAT (P < 0.001). In mice, BAT tissue perfusion increased by 61% (P < 0.01), with no significant changes in blood flow to WAT, muscle, heart, or liver. CL-316,243 increased glucose uptake in BAT even more, by 440% (P < 0.01).Pharmacologic activation of BAT requires increased blood flow to deliver glucose and oxygen for thermogenesis. However, the glucose consumption far exceeds the vascular response. These findings demonstrate that activated BAT increases glucose uptake beyond what might occur by increased blood flow alone and suggest that activated BAT likely uses glucose for nonthermogenic purposes.

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Dataset Information

A Nordic survey of CT doses in hybrid PET/CT and SPECT/CT examinations.

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A Nordic survey of CT doses in hybrid PET/CT and SPECT/CT examinations.

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