Diagnostic value of coronary flow reserve assessment by dynamic 99mTc-MIBI SPECT-CZT gamma camera for the detection of coronary artery disease

Background

Coronary flow reserve (CFR) obtained by dynamic acquisition of myocardial blood flow using 99mTc-MIBI SPECT-CZT gamma camera may be useful to diagnose myocardial perfusion defects in patients with coronary artery disease (CAD).

Purpose

To assess the feasibility and diagnostic value of SPECT-derived CFR in patients with suspected of confirmed CAD.

Methods

The study group comprised 55 patients (pts) (43.6% females, mean age 64.6±8.4 years) with suspected CAD who were referred for scheduled coronary angiography. All pts underwent myocardial perfusion study with solid-state CZT nuclear camera (dipyridamole stress protocol) to calculate myocardial blood flow reserve. We measured total CFR, as well as CFR in three coronary territories: left anterior descending artery (LAD CFR), right coronary artery (RCA CFR) and left circumflex artery (LCx CFR).

Results

On coronary angiography 27 pts were found to have significant CAD (at least one major coronary artery ≥70% narrowed). Mean total CFR in pts with CAD was lower than in pts without CAD (1.73±0.59 vs 2.09±0.56, respectively, p=0.02). Similar differences were noted in LAD territory (1.47±0.57 vs 2.00±0.57; respectively, p=0.004) and RCA territory (1.55±0.54 vs 2.01±0.62; respectively, p=0.03). However, the differences in LCx CFR between CAD and no-CAD group did not reach statistical significance. Modest, but significant correlations were detected between LAD CFR and the percentage of LAD stenosis (r=−0.3; p=0.02). Total CFR has acceptable diagnostic value for detecting significant CAD (AUC=0.672; p=0.03). The criterion with the highest diagnostic accuracy was CFR <1.8 – its sensitivity was 63%, specificity 71.4%, and overall accuracy 67%. In analysis of coronary territories the highest diagnostic value was achieved for CFR LAD (AUC=0.744; p=0.007).

Conclusions

SPECT-derived CFR provides acceptable diagnostic accuracy for the detection of significant CAD.

Funding Acknowledgement

Type of funding sources: None.

Left ventricular longitudinal strain impairment at rest correlates with reduction of SPECT-derived coronary flow reserve in patients with suspected coronary artery disease

Background

Speckle tracking echocardiography (STE) may be useful for the detection of subclinical systolic function abnormalities. Dynamic acquisition of myocardial blood flow using 99mTc-MIBI SPECT-CZT gamma camera allows the calculation of coronary flow reserve (CFR).

Purpose

The aim of our study is to assess the relationship between left ventricular longitudinal strain (LS) and CFR in patients with suspected coronary artery disease (CAD).

Methods

55 patients (pts) (43.6% females, mean age 64.6±8.4 years) with suspected CAD underwent transthoracic echocardiography with assessment global and local LS by STE. We calculated mean global left ventricular LS (GLS), as well as LS of individual coronary artery territories (LAD LS, LCx LS and RCA LS). All pts underwent myocardial perfusion study with novel solid-state CZT nuclear camera (dipyridamole stress protocol). We measured CFR of the left ventricle and individual coronary territories.

Results

Mean absolute GLS in pts with total CFR <2 was significantly lower than in pts with CFR >2 (median value −13.9 vs −18.3; p<0.001). Similar differences were observed in all three coronary territories (p≤0.01). Modest but significant correlations were detected between total CFR and GLS values (r=−0.56; p<0.001), LAD CFR and LAD LS (r=−0.54; p<0.001), RCA CFR and RCA LS (r=−0.36; p=0.007), LCx CFR and LCx LS (r=−0.53; p<0.001). GLS at rest had good diagnostic value for detecting total CFR <2 (AUC=0.767; p<0.001). The criterion with the highest diagnostic accuracy was GLS > (−15.8) – its sensitivity was 68%, specificity 77.7%, and overall accuracy 73%.

Conclusions

Indices of left ventricular longitudinal function obtained by speckle tracking echocardiography correlate with SPECT-derived CFR in patients with suspected CAD.

Funding Acknowledgement

Type of funding sources: None.

Kidney Efficiency Index - quantitative parameter of a dynamic renal scintigraphy. I. Theory and preliminary verification

BACKGROUND

One of the basic clinical indications for dynamic renal scintigraphy (DRS) is a diagnosis of obstructive uropathy and/or nephropathy. Currently, a basic quantitative criterion for diagnosing nephropathy is the percentage of individual kidney's contribution in the global uptake of a radiopharmaceutical from the blood (so-called Split Function - SF). From a clinical point of view, a parameter evaluating a radiopharmaceutical uptake and reflecting the efficiency of a specific kidney, determined independently of the total uptake of both kidneys, would be much more useful. Based on a Rutland theory, a kidney uptake constant K proportional to a radiotracer uptake by individual kidney was introduced and applied to DRS with 99mTc-ethylene-1-dicysteine (99mTc-EC). In addition, a kidney efficiency index (KEi) was also worked out as a new parameter obtained by dividing the uptake constant K by the surface of the ROI of a given kidney, which can be interpreted as the average "efficiency" of clearance of a kidney.

MATERIAL AND METHODS

K and KEi values were verified in 72 studies selected retrospectively from patients referred routinely for DRS, with available current level of blood creatinine, used for calculation of estimated GFR (eGFR) according to a CKD-EPI formula. After splitting of eGFR values into individual kidneys according to SF, single kidney eGFR values (SKeGFR) were obtained and then used as a verification method for SF, K and KEi values.

RESULTS

Correlation between SF and SKeGFR values, rsp = 0.64, was significantly weaker (p < 0.0022) than the correlation of SKeGFR values with K uptake constants and KEi indices: 0.90 and 0.84, respectively.

CONCLUSIONS

Uptake constant K and KEi, as quantitative parameters, give the opportunity to analyze a function of each kidney separately and in an absolute way. KEi also allows for a reliable assessment of kidneys of atypical sizes (larger or smaller than average). It also gives the opportunity to create normative values for this parameter and may be useful in a number of clinical situations where the diagnostic effectiveness of such a relative parameter as SF, is severely limited, e.g. in assessing a large kidney with hydronephrosis or while differing a cirrhotic from hypoplastic (i.e. a small but properly functioning) kidney.

Kidney efficiency index quantitative parameter of a dynamic renal scintigraphy. II. usefulness in the diagnosis of obstructive nephropathy

BACKGROUND

One of the main indications for DRS is a diagnosis of obstructive uro-/nephropathy. In standard practice, this study includes the assessment of sequential scintigraphic images, renographic curves and such quantitative parameters as TMAX, T1/2 and split function of each kidney (SF). Due to the relative nature of SF and limitations of diagnostic capabilities of TMAX and T1/2, DRS was expanded to include new quantitative parameters describing kidney function in absolute values. This study aims to evaluate the usefulness of kidney efficiency index (KEi) - new, in-house developed parameter proportional to the average clearance function of the kidney.

MATERIAL AND METHODS

The study included 156 people aged 18-84 (average 51) years. The first group, from which normative values of new parameters were determined, consisted of 20 healthy volunteers. The second group consisted of 136 patients selected retrospectively, based on archived scintigraphic data. "Normalcy rate" (percentage of normal results among selected 62 patients with a low likelihood of obstructive uro-/nephropathy) was used to evaluate the reliability of KEi. A comparative differential analysis of obstructive uro-/nephropathy, based on standard and new DRS parameters, was performed on selected 74 patients (92 kidneys) with single functioning kidney or bilateral obstructive uropathy, where SF is unreliable.

RESULTS

Normative values: KEi ≥ 8; Normalcy rate for KEi: 95%. In comparison with standard DRS evaluation, application of KEi changed the diagnosis in 1/3 of assessed kidneys (from uropathy to nephropathy in 27/92 kidneys and vice versa in 4 kidneys).

CONCLUSIONS

KEi enables reproducible, quantitative assessment of absolute kidney function without any modifications of the standard DRS protocol. Its values can be compared between independent studies (e.g. follow-up examinations). KEi corrected the diagnosis of obstructive uro-/nephropathy in cases of single functioning kidney or bilateral obstructive uropathy.

Occlusive Coronary Thrombosis and Oral Anticoagulants

The results of post-mortem examination in 173 patients followed over an average period of five and a half years after their initial myocardial infarction are described. These 173 patients were divided into four groups according to whether or not they had received an oral anticoagulant and if so how adequately. An index of coronary and myocardial lesions was established for each heart. Recent occlusive coronary thromboses were four times less frequent in the group of patients who had received adequate anticoagulant therapy than in the other three groups of patients (p˂0,001). There was no significant difference between the inadequately treated groups and the untreated group. The recurrences of myocardial infarction were associated in 90 per cent of the cases with a recent occlusive thrombosis in the corresponding coronary artery and were found four times less frequently in the group subjected to effective long-term anticoagulant therapy (p˂0,001).

Sulfonylurea improves CNS function in a case of intermediate DEND syndrome caused by a mutation in KCNJ11

BACKGROUND

A 12-week-old female presented with neonatal diabetes. Insulin therapy alleviated the diabetes, but the patient showed marked motor and mental developmental delay. The patient underwent genetic evaluation at the age of 6 years, prompted by reports that mutations in the KCNJ11 gene caused neonatal diabetes.

INVESTIGATIONS

Genomic sequencing of the ATP-sensitive potassium (K(ATP)) channel gene KCNJ11 and in vitro functional analysis of the channel defect, and single-photon emission CT imaging before and after glibenclamide therapy.

DIAGNOSIS

Genetic evaluation revealed a missense mutation (His46Leu) in KCNJ11, which encodes the Kir6.2 subunit of the K(ATP) channel, conferring reduced ATP sensitivity. Functional studies demonstrated that the mutant channels were strongly inhibited by the sulfonylurea tolbutamide.

MANAGEMENT

Sulfonylurea (glibenclamide) treatment led to both improved glucose homeostasis and an increase in mental and motor function.

[Diagnostic methods of central nervous system changes in SLE patients]

Systemic lupus erythematosus is an autoimmune, multiorgan disease, in the course of which central nervous system (CNS) disturbances are usually observed. Pathomechanism of CNS changes is complex and not fully investigated. Neuropathological alterations are often not characteristic, usually caused by vasculopathy, infarction, hemorrhages or infection. Vascular changes are generally disseminated and develop in different time period, sometimes they precede clinical symptoms. Currently applied diagnostic methods and their usefulness in diagnosis of CNS involvement in lupus patients, especially single photon emission computed tomography (SPECT), are presented.

Clinical usefulness of 99mTc-EDDA/HYNIC-TOC scintigraphy in oncological diagnostics: a pilot study

The clinical usefulness of a new 99mTc-labeled somatostatin analogue has been studied from the standpoint of oncological diagnostics. The group of patients studied included 40 individuals with diagnosed malignant neoplasms (32 primary and 8 metastatic). Among the primary tumors were 7 pituitary adenomas (5 hormonally active and 2 inactive), 1 liposarcoma, 2 carcinoids, 1 breast carcinoma, and 21 cases of lung cancer (2 small cell and 19 non-small cell) were represented. The metastatic tumors consisted of: 3 malignant melanomas, 1 pheochromocytoma, 1 prostatic cancer, 1 leiomyosarcoma, 1 pancreatic carcinoma ectopically secreting ACTH, and 1 carcinoid of the thymus. The radiopharmaceutical, 99mTc-EDDA/HYNIC-octreotide, was i.v. administered at the activity of 740-925 MBq. The imaging was comprized of a whole-body scan and single photon emission computed tomography. Positive scintigrams were obtained in 4 of 5 hormonally active pituitary adenomas, in 1 of 2 cases of carcinoid, in liposarcoma, breast cancer, and all cases of small cell (SCLC) and non-small cell lung cancer (NSCLC). The neoplastic metastases were visualized in 2 of 3 cases of melanoma and in patients with pheochromocytoma, pancreatic carcinoma secreting ACTH, and thymic carcinoid. Scintigrams were negative in both hormonally inactive pituitary adenomas, in one case of metastatic malignant melanoma, leiomyosarcoma, and in cases of metastasis from the prostatic carcinomas. The results of this pilot study indicated that 99mTc-EDDA/HYNIC-TOC is a potentially useful radiopharmaceutical for the imaging of a wide range of primary and metastatic tumors. More detailed indications for the clinical usefulness of the new tracer for the imaging of selected tumor types require studies on much larger groups of patients. Special attention should be paid to the successful imaging of all cases of NSCLC.

Quantitative assessment of technetium-99m methoxyisobutylisonitrile planar perfusion heart studies: application of multivariate analysis to patient classification

A quantified evaluation of planar cardiac perfusion scintigrams (the objective of the study), obtained using technetium-99m methoxyisobutylisonitrile (MIBI) was performed on the basis of an analysis of circumferential profile curves, representing the perfusion as seen in three typical projections. The analysis involved the curves obtained both at rest and after stress, and was based on a comparison of their shape (trend) with the normal trend (normative evaluation). The latter was obtained by means of an original method of iterative fitting of individual curves into the database. The base consisted of curves recorded in 53 patients (separately in males and females) with normal perfusion of the left ventricle (group I, the reference group). A group of 90 patients suspected of having coronary artery disease (group II) was subdivided into two subgroups on the basis of coronary arteriography: (a) those with and (b) those without critical stenosis of at least one artery. Profile curves characterising the LV perfusion were obtained at rest and after stress. Defects of perfusion were quantified by comparison of individual curves with the normal trends. By means of multivariate analysis it was demonstrated that vectors of mean values characterising the scintigraphically assessed defects of LV perfusion in the two subgroups of group II differed very significantly (P < 10(-5)). Applying methods of discriminant analysis, a classification of patients from group II was performed into those with probable defects of perfusion and those free of such defects. The sensitivity, specificity and accuracy of diagnosis of coronary ischaemia, based on quantified planar 99mTc-MIBI scintigraphy, reached 86%, 87% and 87%, respectively.

Quantitative bone scintigraphy in patients with hyperparathyroidism

Laboratory tests, including the determination of parathormone in serum, and x-ray examinations are often of limited value in diagnosing hyperparathyroidism (HPT). In this study, bone scintigraphy was carried out in 15 patients with proven HPT (primary and secondary in patients with chronic renal disease) and 25 normal subjects, to evaluate quantitatively increased bone metabolism. The count density ratios bone to soft tissue (D/S-index) were calculated. In normal, this D/S index averaged 3.66 +/- 0.94 and was significantly (p less than 0.001) different to that of HPT-patients averaging 6.37 +/- 1.64. The quantitative evaluation shows a sensitivity of 73%, a specificity of 100% and an accuracy of 90% for detecting HPT (based on the sample values). Discriminant analysis can be applied to calculate the probability of the presence of HPT (primary and secondary) as a function of the measured D/S index.

Occlusive coronary thrombosis and oral anticoagulants

The results of post-mortem examination in 173 patients followed over an average period of five and a half years after their initial myocardial infarction are described. These 173 patients were divided into four groups according to whether or not they had received an oral anticoagulant and if so how adequately. An index of coronary and myocardial lesions was established for each heart. Recent occlusive coronary and myocardial lesions was established for each heart. Recent occlusive coronary thromboses were four times less frequent in the group of patients who had received adequate anticoagulant therapy than in the other three groups of patients (p less than 0,001). There was no significant difference between the inadequately treated groups and the untreated group. The recurrences of myocardial infarction were associated in 90 per cent of the cases with a recent occlusive thrombosis in the corresponding coronary artery and were found four times less frequently in the group subjected to effective long-term anticoagulant therapy (p less than 0,001).

[Coronary thrombosis and long term anticoagulant treatment. Results of 173 autopsies after myocardial infarction]

Report of an anatomical-clinical study concerning 173 patients with an average follow-up period of 5 and 1/2 years after the onset of myocardial infarction. They were subdivided into four comparable groups differing only in the quality of the long-term antivitamin K treatment which was administered. A survey of the coronary artery and myocardial lesions was performed for every heart. Acute occlusive coronary artery thromboses were four times less frequent in the correctly treated group then in the other three groups (p less than 0.001). There was no significant difference between the insufficiently treated groups and the untreated group. Recurrent myocardial infarctions were accompanied in 90 per cent of cases by acute occlusive coronary artery thromboses and were four times less frequent when treatment was efficient (p less than 0.001). These results confirm the part played by coronary artery thrombosis in the aggravation of coronary atherosclerosis and justify the attempts at long-term prophylaxis. The provide the proof that antivitamin K administration, at efficient dosage, maintained for a long time, has a significant influence on the cause of death in these patients, by decreasing the number of coronary artery thrombosis. Long-term anticoagulant treatment, in spite of its haemorrhagic complications and limits, should not be given up until a new efficient treatment is available.