Myocardial perfusion imaging (MPI) is well established in the diagnosis and workup of patients with known or suspected coronary artery disease (CAD); however, it can underestimate the extent of obstructive CAD. Quantification of myocardial perfusion reserve with PET can assist in the diagnosis of multivessel CAD. We evaluated the feasibility of dynamic tomographic SPECT imaging and quantification of a retention index to describe global and regional myocardial perfusion reserve using a dedicated solid-state cardiac camera.
Methods
Ninety-five consecutive patients (64 men and 31 women; median age, 67 y) underwent dynamic SPECT imaging with 99mTc-sestamibi at rest and at peak vasodilator stress, followed by standard gated MPI. The dynamic images were reconstructed into 60–70 frames, 3–6 s/frame, using ordered-subsets expectation maximization with 4 iterations and 32 subsets. Factor analysis was used to estimate blood-pool time–activity curves, used as input functions in a 2-compartment kinetic model. K1 values (99mTc-sestamibi uptake) were calculated for the stress and rest images, and K2 values (99mTc-sestamibi washout) were set to zero. Myocardial perfusion reserve (MPR) index was calculated as the ratio of the stress and rest K1 values. Standard MPI was evaluated semiquantitatively, and total perfusion deficit (TPD) of at least 5% was defined as abnormal.
Results
Global MPR index was higher in patients with normal MPI (n = 51) than in patients with abnormal MPI (1.61 [interquartile range (IQR), 1.33–2.03] vs. 1.27 [IQR, 1.12–1.61], P = 0.0002). By multivariable regression analysis, global MPR index was associated with global stress TPD, age, and smoking. Regional MPR index was associated with the same variables and with regional stress TPD. Sixteen patients undergoing invasive coronary angiography had 20 vessels with stenosis of at least 50%. The MPR index was 1.11 (IQR, 1.01–1.21) versus 1.30 (IQR, 1.12–1.67) in territories supplied by obstructed and nonobstructed arteries, respectively (P = 0.02). MPR index showed a stepwise reduction with increasing extent of obstructive CAD (P = 0.02).
Conclusion
Dynamic tomographic imaging and quantification of a retention index describing global and regional perfusion reserve are feasible using a solid-state camera. Preliminary results show that the MPR index is lower in patients with perfusion defects and in regions supplied by obstructed coronary arteries. Further studies are needed to establish the clinical role of this technique as an aid to semiquantitative analysis of MPI.
The variety of foreign bodies inserted into or externally attached to the genitourinary tract defies imagination and includes all types of objects. The frequency of such cases renders these an important addition to the diseases of the genitourinary organs. The most common motive associated with the insertion of foreign bodies into the genitourinary tract is sexual or erotic in nature. In adults this is commonly caused by the insertion of objects used for masturbation and is frequently associated with mental health disorders. We report a case of insertion of telephone cable wire into the urethra. Our case highlights the importance of good history, clinical examination, relevant radiological investigation and simple measures to solve the problem.
The objective of this study was to assess the impact of Ga-prostate-specific membrane antigen (Ga-PSMA) PET/CT on the management of prostate cancer in patients with biochemical recurrence (BCR). Documented management plans before and afterGa-PSMA PET/CT in 100 patients with BCR were retrospectively reviewed, and changes in plans were recorded. Management changed afterGa-PSMA PET/CT in 39 patients (39%). The management changes occurred in 23 (33.8%) of 68 patients with radical prostatectomy and 16 (50%) of 32 patients previously treated with radical radiotherapy. Positive scan results ( < 0.001) and higher prostate-specific antigen (PSA) levels ( = 0.024) were associated with management changes. No significant association with management change was found for Gleason grade, stage, presence of metastatic disease, PSA velocity, or PSA doubling time. Ga-PSMA PET/CT altered management in 39% of patients with BCR, and changes occurred more often in patients with radical radiotherapy treatment, positiveGa-PSMA scan results, and higher PSA levels.
SMADT results in better localization of varying parathyroid pathologies and complements the role of US in patients with multigland disease and nodular thyroid.
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