Quantitation of myocardial 99mTc-HMDP uptake with new SPECT/CT cadmium zinc telluride (CZT) camera in patients with transthyretin-related cardiac amyloidosis: Ready for clinical use?

BACKGROUND: The aim of this study was to investigate the feasibility of assessing absolute myocardial 99mTc-HMDP uptake in patients with suspected cardiac ATTR using SUV with a whole-body CZT SPECT-CT camera (DNM670CZT). METHODS: Fifteen patients with suspected cardiac ATTR (Perugini ≥ 2) underwent a conventional 99mTc-HMDP planar imaging and a thoracic SPECT/CT using a DNM 670CZT. A control group consisted of 15 patients with negative scintigraphy (Perugini < 2). SUVmax (mg·L-1) and percentage of injected dose (%ID) were calculated in a cardiac volume of interest (VOI) encompassing the left ventricle. VOIs were also placed in the lung, the right pectoris major, and the sternum. A heart-to-lung SUVmax ratio (HLR) was calculated. RESULTS: All ATTR patients demonstrated an increased cardiac HMDP SUVmax (12.2 ± 3.7 mg·L-1) vs controls (3.5 ± 1.2, P < .0001). Percentage of ID, pectoral uptake and HLR were significantly higher in the ATTR group (1.1 ± 0.3 vs 0.15 ± 0.8, P < .0001; 1.5 ± 0.3 vs 0.9 ± 0.3, P < .0001; 9.7 ± 3 vs 4.3 ± 2.2, P < .0001). Bone uptake was not statistically different between the two groups. CONCLUSION: This study demonstrated the feasibility of quantitative 99mTc-HMDP SUVmax measurement using a whole-body SPECT/CT CZT camera in patients with suspected cardiac ATTR.

First Follow-Up of Cardiac Amyloidosis Treated by Tafamidis, Evaluated by Absolute Quantification in Bone Scintigraphy.

Assessment of absolute myocardial hydroxydimethylene diphosphonate-technetium-99m uptake using standardized uptake value with a single-photon emission computed tomography-computed tomography cadmium zinc telluride camera (Discovery NM/CT 670CZT, GE Healthcare, Chicago, Illinois) in a patient with cardiac transthyretin-related amyloidosis treated with tafamidis showed a decrease in hydroxydimethylene diphosphonate cardiac uptake. This imaging technique should be helpful in monitoring therapy and evaluating prognosis. (Level of Difficulty: Intermediate.).

Deleterious effect of right ventricular pacing in patients with cardiac transthyretin amyloidosis: potential clinical benefit of cardiac resynchronization therapy.

BACKGROUND: Cardiac amyloidosis involvement is associated with a detrimental outcome including frequent arrhythmias, heart failure, and conduction disturbances which may need permanent pacing. CASES SUMMARY: We report two cases of patients with transthyretin amyloidosis (ATTR) who developed heart failure and depressed left ventricular ejection fraction (LVEF) following permanent right ventricular (RV) pacing but highly responded to cardiac resynchronization therapy (CRT). DISCUSSION: The impact of RV pacing and CRT in cardiac amyloidosis is not known. In our cases, the detrimental effect of permanent RV pacing on left ventricular (LV) systolic function and heart failure symptoms was suggested by both permanent RV pacing mediated functional and LV function decline and LV systolic dysfunction reversal following CRT along with QRS width reduction. Whether cardiac resynchronization should be readily recommended in ATTR patients who need ventricular pacing whatever the LVEF deserves further investigation.

First comparison of performances between the new whole-body cadmium-zinc-telluride SPECT-CT camera and a dedicated cardiac CZT camera for myocardial perfusion imaging: Analysis of phantom and patients.

BACKGROUND: Dedicated cardiac Cadmium-zinc-telluride (CZT) cameras show superior performances compared with Anger systems, particularly in terms of spatial resolution and count sensitivity. This study evaluated the performances of a new polyvalent whole body CZT camera (DNM 670CZT) compared with a cardiac dedicated CZT camera (DNM 530c) for myocardial perfusion SPECT. METHODS: The spatial resolution was evaluated with three linear sources filled with 99mTc. We used a cardiac phantom to evaluate count sensitivity, sharpness index, contrast-to-noise ratio, wall thickness, non-uniformity index, perfusion scores and ventricle volumes for both cameras. The impact of matrix size, and acquisition time was investigated. Concordance between the two cameras was evaluated in patients using QPS/QGS software for quantitative segmental perfusion, motion and thickness scores. RESULTS: The spatial resolution was identical with the two cameras. Count sensitivity of the DNM 670CZT was twofold lower compared with the DNM 530c, leading to lower sharpness index and contrast-to-noise ratio. The wall thickness and the myocardial volumes were similar. Visual and quantitative assessments of the perfusion patterns have shown a good concordance of the two cameras on phantoms and in patients. CONCLUSION: This study demonstrated the feasibility of myocardial perfusion SPECT imaging using the new whole-body DNM 670CZT camera.

Determination of the Heart-to-Mediastinum Ratio of 123I-MIBG Uptake Using Dual-Isotope (123I-MIBG/99mTc-Tetrofosmin) Multipinhole Cadmium-Zinc-Telluride SPECT in Patients with Heart Failure.

The aim of this retrospective study was to compare the heart-to-mediastinum ratio (HMR) of 123I-metaiodobenzylguanidine (123I-MIBG) uptake obtained using a multipinhole cadmium-zinc-telluride (CZT) camera with that obtained using conventional planar imaging. Methods: Forty consecutive heart failure patients underwent planar acquisition 4 h after 123I-MIBG injection (191 ± 41 [mean ± SD] MBq). To localize the heart using the CZT camera, 99mTc-tetrofosmin (358 ± 177 MBq) was administered and dual-isotope acquisition was performed. The HMRs were calculated with conventional planar imaging (HMRplanar), with anterior reprojection images using the CZT camera (HMRreproj), and with transaxial reconstructed images using the CZT camera (HMRtransaxial). In a phantom study, we estimated a linear model fitting the CZT camera data to the planar data, and we applied it to provide corrected CZT camera-determined HMRs in patients (cHMRreproj and cHMRtransaxial). Results: Thirty-four men and 6 women (71 ± 9 y old) with ischemic (22 patients) and nonischemic (18 patients) heart failure completed the study. For 22 of the 40 patients (55%), the New York Heart Association classification was class II and the ejection fraction was 35% ± 9%. HMRreproj (1.12 ± 0.19) and HMRtransaxial (1.35 ± 0.34) were lower than HMRplanar (1.44 ± 0.14) (P < 0.0001 and P < 0.01, respectively). cHMRreproj (1.54 ± 0.09) and cHMRtransaxial (1.45 ± 0.14) were significantly different (P < 0.0001). Lin concordance correlation and Bland-Altman analysis demonstrated an almost perfect concordance and a high agreement between HMRplanar and cHMRtransaxial (P was not significant) but not between HMRplanar and cHMRreproj (P < 0.0001). Conclusion: This study demonstrated that determination of the late HMR of cardiac 123I-MIBG uptake using dual-isotope (123I and 99mTc) acquisition on a multipinhole CZT camera was feasible in patients with heart failure. However, this determination should be performed using transaxial reconstructed images and linear correction based on phantom data acquisitions.

First assessment of simultaneous dual isotope (123I/99mTc) cardiac SPECT on two different CZT cameras: A phantom study.

BACKGROUND: We studied the impact of simultaneous dual-isotope acquisition on 123I/99mTc mismatch assessment using two CZT cameras (DNM 530c, GE Healthcare and DSPECT, Biosensors International). METHODS: We used an anthropomorphic torso phantom (respectively filled with a solution of 123I alone, 99mTc alone, and a mixture of 123I and 99mTc) and its cardiac insert with two defects mimicking two matched and mismatched defects. Mismatch extent and reconstructed image contrast were evaluated. RESULTS: The acquisition mode (single vs dual) significantly impacted (i) 99mTc (but not 123I) reconstructed segmental activities using both camera (P < .001), and (ii) image contrast (using 123I and DNM 530c, P < .0001; and using both 123I and 99mTc with DSPECT, P < .0001). However, the defect and mismatch size were not impacted by the type of acquisition. With both DNM 530c and DSPECT, Lin's concordance correlation coefficient and Bland-Altman analysis demonstrated an almost perfect concordance and agreement between single- and simultaneous dual-isotope segmental activity (123I and 99mTc). CONCLUSIONS: This study found no impact of the acquisition mode (single vs dual) or the type of camera (DSPECT vs DNM 530c) on 123I and 99mTc defect size and mismatch, providing a new step toward simultaneous dual-isotope acquisition for combined innervation and perfusion assessment.

Lung perfusion characteristics in pulmonary arterial hypertension (PAH) and peripheral forms of chronic thromboembolic pulmonary hypertension (pCTEPH): Dual-energy CT experience in 31 patients.

PURPOSE: To compare lung perfusion in PAH and pCTEPH on dual-energy CT (DECT) examinations. MATERIALS AND METHODS: Thirty-one patients with PAH (group 1; n = 19) and pCTEPH (group 2; n = 12) underwent a dual-energy chest CTA with reconstruction of diagnostic and perfusion images. Perfusion alterations were analysed at a segmental level. V/Q scintigraphy was available in 22 patients (group 1: 13/19; group 2: 9/12). RESULTS: CT perfusion was abnormal in 52.6 % of group 1 patients and in 100 % of group 2 patients (p = 0.0051). The patterns of perfusion alteration significantly differed between the two groups (p < 0.0001): (1) in group 1, 96.6 % of segments with abnormal perfusion showed patchy defects; (2) in group 2, the most frequent abnormalities consisted of patchy (58.5 %) and PE-type (37.5 %) defects. Paired comparison of CT perfusion and scintigraphy showed concordant findings in 76.9 % of group 1 (10/13) and 100 % of group 2 (9/9) patients, with a predominant or an exclusive patchy pattern in group 1 and a mixed pattern of abnormalities in group 2. CONCLUSION: Lung perfusion alterations at DECT are less frequent and more homogeneous in PAH than in pCTEPH, with a high level of concordant findings with V/Q scintigraphy. KEY POINTS: • Depiction of chronic pulmonary embolism exclusively located on peripheral arteries is difficult. • The main differential diagnosis of pCTEPH is PAH. • The pattern of DECT perfusion changes can help differentiate PAH and pCETPH. • In PAH, almost all segments with abnormal perfusion showed patchy defects. • In pCTEPH, patchy and PE-type defects were the most frequent abnormalities.

18F-FDG PET/CT in Renal Infections: Evidence of Acute Pyelonephritis in a Horseshoe Kidney.

A 58-year-old paraplegic patient was prescribed F-FDG for persistent inflammatory syndrome after aortic surgery for dissection. The examination was performed on a Siemens mCT Flow PET/CT and shows a moderate prostate uptake, related to prostatitis on self-catheterization and a focal renal cortical hypermetabolism of the left medial midpole of a horseshoe kidney, which corresponds to renal parenchyma on the CT, and suggests pyelonephritis, confirmed by Tc-DMSA SPECT/CT.

Left ventricular function assessment using 123I/99mTc dual-isotope acquisition with two semi-conductor cadmium-zinc-telluride (CZT) cameras: a gated cardiac phantom study.

BACKGROUND: The impact of increased energy resolution of cadmium-zinc-telluride (CZT) cameras on the assessment of left ventricular function under dual-isotope conditions (99mTc and 123I) remains unknown. The Amsterdam-gated dynamic cardiac phantom (AGATE, Vanderwilt techniques, Boxtel, The Netherlands) was successively filled with a solution of 123I alone, 99mTc alone, and a mixture of 123I and 99mTc. A total of 12 datasets was acquired with each commercially available CZT camera (DNM 530c, GE Healthcare and DSPECT, Biosensors International) using both energy windows (99mTc or 123I) with ejection fraction set to 33, 45, and 60 %. End-diastolic (EDV) and end-systolic (ESV) volumes, ejection fraction (LVEF), and regional wall motion and thickening (17-segment model) were assessed using Cedars-Sinai QGS Software. Concordance between single- and dual-isotope acquisitions was tested using Lin's concordance correlation coefficient (CCC) and Bland-Altman plots. RESULTS: There was no significant difference between single- or simultaneous dual-isotope acquisition (123I and 99mTc) for EDV, ESV, LVEF, or segmental wall motion and thickening. Myocardial volumes using single- (123I, 99mTc) and dual-isotope (reconstructed using both 123I and 99mTc energy windows) acquisitions were, respectively, the following: EDV (mL) 88 ± 27 vs. 89 ± 27 vs. 92 ± 29 vs. 90 ± 26 for DNM 530c (p = NS) and 82 ± 20 vs. 83 ± 22 vs. 79 ± 19 vs. 77 ± 20 for DSPECT (p = NS); ESV (mL) 40 ± 1 vs. 41 ± 2 vs. 41 ± 2 vs. 42 ± 1 for DNM 530c (p = NS) and 37 ± 5 vs. 37 ± 1 vs. 35 ± 3 vs. 34 ± 2 for DSPECT (p = NS); LVEF (%) 52 ± 14 vs. 51 ± 13 vs. 53 ± 13 vs. 51 ± 13 for DNM 530c (p = NS) and 52 ± 16 vs. 54 ± 13 vs. 54 ± 14 vs. 54 ± 13 for DSPECT (p = NS); regional motion (mm) 6.72 ± 2.82 vs. 6.58 ± 2.52 vs. 6.86 ± 2.99 vs. 6.59 ± 2.76 for DNM 530c (p = NS) and 6.79 ± 3.17 vs. 6.81 ± 2.75 vs. 6.71 ± 2.50 vs. 6.62 ± 2.74 for DSPECT (p = NS). The type of camera significantly impacted only on ESV (p < 0.001). CONCLUSIONS: The new CZT cameras yielded similar results for the assessment of LVEF and regional motion using different energy windows (123I or 99mTc) and acquisition types (single vs. dual). With simultaneous dual-isotope acquisitions, the presence of 123I did not impact on LVEF assessment within the 99mTc energy window for either CZT camera.

Hyperglycemia-Induced Hypovolemia Is Involved in Early Cardiac Magnetic Resonance Alterations in Streptozotocin-Induced Diabetic Mice: A Comparison with Furosemide-Induced Hypovolemia.

AIMS: The aim of the study was to assess the early features of diabetic cardiomyopathy using cardiac magnetic resonance within the first week after streptozotocin injection in mice. We focused on the relationship between left ventricular function and hypovolemia markers in diabetic animals compared to a hypovolemic rodent model. METHODS AND RESULTS: Swiss mice were randomized into control (group C), streptozotocin-induced diabetes (group D) and furosemide-induced hypovolemia (group F) groups. Cardiac magnetic resonance, non-invasive blood pressure, urine volume, plasma markers of dehydration and cardiac histology were assessed in all groups. Mean blood glucose was higher in diabetic animals than in groups C and F (30.5±5.8 compared to 10.4±2.1 and 11.1±2.8 mmol/L, respectively; p<0.01). Diuresis was increased in animals from group D and F compared to C (14650±11499 and 1533±540 compared to 192±111 µL/24 h; p<0.05). End diastolic and end systolic volumes were lower in group D than in group C at week 1 (1.52±0.36 vs. 1.93±0.35 and 0.54±0.22 vs. 0.75±0.18 mL/kg, p<0.05). These left ventricular volume values in group D were comparable to those observed in the acute hypovolemia model (group F). Increased dehydration plasma markers and an absence of obvious intrinsic myocardial damage (evaluated by cardiac magnetic resonance and histology) suggest that a hemodynamic mechanism underlies the very early drop in left ventricular volumes in group D and provides a potential link to hyperglycemic osmotic diuresis. CONCLUSIONS: Researchers using cardiac magnetic resonance in hyperglycemic rodent models should be aware of this hemodynamic mechanism, which may partially explain modifications in cardiac parameters in addition to diabetic myocardial damage.

First determination of the heart-to-mediastinum ratio using cardiac dual isotope (¹²³I-MIBG/99mTc-tetrofosmin) CZT imaging in patients with heart failure: the ADRECARD study.

PURPOSE: Cardiac innervation is assessed using the heart-to-mediastinum ratio (HMR) of metaiodobenzylguanidine (MIBG) on planar imaging using Anger single photon emission computed tomography (A-SPECT). The aim of the study was to determine the HMR of MIBG obtained using a CZT-based camera (D-SPECT; Spectrum Dynamics, Israel) in comparison with that obtained using conventional planar imaging. METHODS: The ADRECARD study prospectively evaluated 44 patients with heart failure. They underwent planar acquisition using the A-SPECT camera 4 h after (123)I-MIBG injection (236.4 ± 39.7 MBq). To localize the heart using D-SPECT, (99m)Tc-tetrofosmin (753 ± 133 MBq) was administered and dual isotope acquisition was performed using the D-SPECT system. HMR was calculated using both planar A-SPECT imaging and front view D-SPECT cine data. In a phantom study, we estimated a model fitting the A-SPECT and the D-SPECT data that was further applied to correct for differences between the cameras. RESULTS: A total of 44 patients (39 men and 5 women, aged 60 ± 11 years) with ischaemic (31 patients) and nonischaemic (13 patients) cardiomyopathy completed the study. Most patients (28 of 44) were NYHA class II, and the mean left ventricular ejection fraction was 33 ± 7 %. The mean HMR values were 1.34 ± 0.15 and 1.45 ± 0.27 from A-SPECT and D-SPECT, respectively (p < 0.0001). After correction, Lin's concordance correlation showed an almost perfect concordance between corrected D-SPECT HMR and A-SPECT HMR, and Bland-Altman analysis demonstrated a high agreement between the two measurements. CONCLUSION: The ADRECARD study demonstrated that determination of late HMR during cardiac MIBG imaging using dual isotope ((123)I and (99m)Tc) acquisition on a CZT camera (D-SPECT) is feasible in patients with heart failure. A linear correction based on the phantom study yielded a high agreement between (123)I MIBG HMR obtained using a CZT camera and that from conventional planar imaging.

Staging the axilla in breast cancer patients with ¹8F-FDG PET: how small are the metastases that we can detect with new generation clinical PET systems?

PURPOSE: Point spread function (PSF) reconstruction improves spatial resolution throughout the entire field of view of a PET system and can detect smaller metastatic deposits than conventional algorithms such as OSEM. We assessed the impact of PSF reconstruction on quantitative values and diagnostic accuracy for axillary staging of breast cancer patients, compared with an OSEM reconstruction, with emphasis on the size of nodal metastases. METHODS: This was a prospective study in a single referral centre in which 50 patients underwent an (18)F-FDG PET examination before axillary lymph node dissection. PET data were reconstructed with an OSEM algorithm and PSF reconstruction, analysed blindly and validated by a pathologist who measured the largest nodal metastasis per axilla. This size was used to evaluate PET diagnostic performance. RESULTS: On pathology, 34 patients (68%) had nodal involvement. Overall, the median size of the largest nodal metastasis per axilla was 7 mm (range 0.5 - 40 mm). PSF reconstruction detected more involved nodes than OSEM reconstruction (p = 0.003). The mean PSF to OSEM SUVmax ratio was 1.66 (95 % CI 1.01 - 2.32). The sensitivities of PSF and OSEM reconstructions were, respectively, 96% and 92% in patients with a largest nodal metastasis of >7 mm, 60% and 40% in patients with a largest nodal metastasis of ≤7 mm, and 92% and 69% in patients with a primary tumour ≤30 mm. Biggerstaff graphical comparison showed that globally PSF reconstruction was superior to OSEM reconstruction. The median sizes of the largest nodal metastasis in patients with nodal involvement not detected by either PSF or OSEM reconstruction, detected by PSF but not by OSEM reconstruction and detected by both reconstructions were 3, 6 and 16 mm (p = 0.0064) respectively. In patients with nodal involvement detected by PSF reconstruction but not by OSEM reconstruction, the smallest detectable metastasis was 1.8 mm. CONCLUSION: As a result of better activity recovery, PET with PSF reconstruction performed better than PET with OSEM reconstruction in detecting nodal metastases ≤7 mm. However, its sensitivity is still insufficient for it to replace surgical approaches for axillary staging. PET with PSF reconstruction could be used to perform sentinel node biopsy more safely in patients with a primary tumour ≤30 mm and with unremarkable PET results in the axilla.