Implementing a coronary CT angiography protocol based on the body mass index: Radiation dose reduction, image quality, and diagnostic performance.

OBJECTIVES: To evaluate the relation between the coronary calcium score and the posterior choice of kilovoltage according to radiologists' criteria in a standard coronary CT angiography protocol to rule out coronary disease. To quantify the reduction in ionizing radiation after linking kilovoltage to patients' body mass index in a low-dose protocol with iterative model reconstruction. To evaluate the image quality and diagnostic performance of the low-dose protocol. MATERIAL AND METHODS: We compared anthropometric characteristics, calcium score, kilovoltage levels, size-specific dose estimates (SSDE), and the dose-length product (DLP) between a group of 50 patients who were prospectively recruited to undergo coronary CT angiography with a low-dose protocol and a historical group of 50 patients who underwent coronary CT angiography with the standard protocol. We correlated these parameters, the number of coronary segments that could not be evaluated with and without temporal padding, the attenuation, and the signal-to-noise ratio in the ascending aorta in the low-dose protocol with excellent imaging quality according to a semiquantitative scale. To calculate the diagnostic performance per patient, we used 24-month clinical follow-up including all tests as the gold standard. RESULTS: In the standard protocol, the presence of coronary calcium correlated with the selection of high kilovoltage (p = 0.02); this correlation was not found in the low-dose protocol (p = 0.47). Median values of SSDE and DLP were significantly (p < 0.001) lower and less dispersed in the low-dose protocol [9.22 mGy (IQR 7.84-12.1 mGy) vs. 26.5 mGy (IQR 21.3-36.3 mGy) in the standard protocol] and [97 mGy cm (IQR 78-134 mGy cm) vs. 253 mGy cm (IQR 216-404 mGy cm) in the standard protocol], respectively. The overall quality of the images obtained with the low-dose protocol was considered good or excellent in 96% of the studies. The parameters associated with image quality in a multivariable model (C statistic = 0.792) were heart rate (estimated coefficient, -0,12 [95% confidence interval: -0.2, -0.04]; p < 0.01) and the SSDE (estimated coefficient, -0,26 [95% confidence interval: -0.51, -0.01]; p < 0.05). The CAD-RADS modifier for a not fully evaluable or diagnostic study was used on two occasions (4%); the final measures for the diagnosis of coronary disease were sensitivity 100%, specificity 94%, and efficacy 94%. CONCLUSIONS: In the standard protocol, the radiologist selects higher kilovoltage for CT angiography studies for patients whose previous calcium score indicates the presence of coronary calcium. In the low-dose protocol, linking kilovoltage with body mass index enables the dose of radiation to be reduced by 65% while obtaining excellent or good image quality in 96% of studies and excellent diagnostic performance.

Cost-effectiveness of myocardial perfusion SPECT and stress test according to coronary revascularization therapy, cardiac events and total mortality: Register of 8,496 patients. / Coste-efectividad de la SPECT de perfusión miocárdica y de la prueba de esfuerzo en relación con la revascularización coronaria, eventos cardíacos y mortalidad total. Registro de 8.496 pacientes.

OBJECTIVE: The aim was to analyze the cost-effectiveness ratio (CER) of stress electrocardiogram (ES) and stress myocardial perfusion imaging (SPECT-MPI) according to coronary revascularization (CR) therapy, cardiac events (CE) and total mortality (TM). MATERIAL AND METHODS: A total of 8,496 consecutive patients who underwent SPECT-MPI were followed-up (mean 5.3±3.5years). Cost-effectiveness for coronary bypass (CABG) or percutaneous CR (PCR) (45.6%/54.4%) according to combined electrocardiographic ischemia and scintigraphic ischemia were evaluated. Effectiveness was evaluated as TM, CE, life-year saved observed (LYSO) and CE-LYSO; costs analyses were conducted from the perspective of the health care payer. A sensitivity analysis was performed considering current CABG/PCR ratios (12%/88%). RESULTS: When electrocardiogram and SPECT approaches are combined, the cost-effectiveness values for CABG ranged between 112,589€ (electrocardiographic and scintigraphic ischemia) and 2,814,715€ (without ischemia)/event avoided, 38,664 and 2,221,559€/LYSO; for PCR ranged between 18,824€ (electrocardiographic and scintigraphic ischemia) and 46,377€ (without ischemia)/event avoided, 6,464 and 36,604€/LYSO. To CE: the cost-effectiveness values of the CABG and CPR in presence of electrocardiographic and scintigraphic ischemia were 269,904€/CE-avoided and 24,428€/CE-avoided, respectively; and the €/LYSO of the CABG and PCR were 152,488 and 13,801, respectively. The RCE was maintained for the current proportion of revascularized patients (12%/88%). CONCLUSIONS: Combined ES and SPECT-MPI results, allows differentiation between patient groups, where the PCR and CABG are more cost-effective in different economic frameworks. The major CER in relation to CR, CE and TM occurs in patients with electrocardiographic and scintigraphic ischemia. PCR is more cost-effective than CABG.

Cardiac 18F-FDG PET/CT procedure for the diagnosis of prosthetic endocarditis and intracardiac devices. / Metodología de la PET/TC con 18F-FDG cardíaca para el diagnóstico de la endocarditis protésica y de dispositivos intracardíacos.

Infective endocarditis (IE) is a serious condition with a poor prognosis, its mortality unchanged significantly despite diagnostic and therapeutic advances in the last 30years. The diagnostic ability of the modified Duke criteria in prosthetic endocarditis and/or devices does not exceed 50%, so new tools are necessary for the diagnosis of this entity in this context. The 18F-FDG PET/CTA combines a highly sensitive technique to detect inflammatory-infectious activity with a technique with high anatomical resolution to assess the structural lesions associated with endocarditis. With a diagnostic sensitivity between 91-97%, this hybrid technique has become a useful diagnostic tool for patients with prosthetic valves or devices and suspicion of IE, becoming a major criterion in the diagnostic algorithm of current guidelines. This excellent diagnostic ability depends directly on the quality of the obtained exploration and the knowledge at the time of interpreting the images. The aim of this review is to describe and standardize the methodology of cardiac 18F-FDG PET/CTA in the diagnosis of endocarditis in prosthetic valves and intracardiac devices, with special emphasis on the particularities of the patient's preparation, the PET and CT acquisition procedures, and the subsequent imaging postprocessing and interpretation.

[Positron emission tomography-computed tomography with (18)F-fluorodeoxyglucose in patients with recurrent differentiated thyroid carcinoma and negative radioiodine scan. Diagnostic performance and relation with tyroglobulin levels]. / La tomografía por emisión de positrones-tomografía computarizada con (18)F-fluordesoxiglucosa en los pacientes con cáncer diferenciado de tiroides en recurrencia y rastreo con radioyodo negativo. Rendimiento diagnóstico y relación con los niveles de tiroglobulina.

OBJECTIVE: To assess the diagnostic performance of (18)F-FDG PET-CT scan and its relation to serum thyroglobulin (Tg) levels in patients with differentiated thyroid carcinoma with suspicion of persistence or recurrence of the disease and negative radioiodine scans. MATERIALS AND METHODS: This is a retrospective analysis of 35 PET-CT studies in 25 patients (17 women, average age 48.8±15.2 years). The results were confirmed by histology or by ultrasonography and clinical follow-up. We analyzed the relationship between the diagnostic performance of the PET-CT scans and three levels of Tg: ≤2ng/ml; between 2 and 10 ng/ml, and >10ng/ml. RESULTS: We obtained 26 true-positives (TP), one false-positive (FP), 3 true-negatives (TN) and 5 false-negatives (FN). Of the 18 patients with PET-CTs classified as TP, 3 showed lesions at the post-thyroidectomy bed, 15 showed lymph node metastases and 5 were distant metastases. Sensitivity was 83.9% (95%CI: 69.3%-98.4%) and specificity was 75% (95%CI: 20%-100%). Regarding the three intervals of Tg, PET-CT scan showed TP rates of 37.5%, 83% and 100% in patients with Tg levels <2ng/ml, between 2 and 10ng/ml, and >10ng/ml, respectively. CONCLUSIONS: (18)F-FDG PET-CT demonstrates high diagnostic yield in local disease and distant lesions for the population of patients with differentiated thyroid carcinoma and persistence of the disease with negative radioiodine scans at Tg levels above 2ng/ml.

[Image fusion of gated-SPECT and CT angiography in coronary artery disease. Importance of anatomic-functional correlation]. / Fusión de imágenes de gated-SPECT y angiotomografía computarizada en la enfermedad coronaria. Importancia de la correlación anatomicofuncional.

A 77-year old patient was admitted for acute coronary syndrome without ST elevation. His risk was stratified using the myocardial perfusion gated SPECT, mild inferior ischemia being observed. Thus, medical therapy was optimized and the patient was discharged. He continued with exertional dyspnea so a coronary CT angiography was performed. It revealed severe lesions in the proximal RCA. SPECT-CT fusion images correlated the myocardial perfusion defect with a posterior descending artery from the RCA, in a co-dominant coronary area. Subsequently, cardiac catheterism was indicated for his treatment. The current use of image fusion studies is limited to patients in whom it is difficult to attribute a perfusion defect to a specific coronary artery. In our patient, the fusion images helped to distinguish between the RCA and the circumflex artery as the culprit artery of ischemia.

Usefulness of sentinel lymph node detection in early stages of cervical cancer.

PURPOSE: Sentinel lymph node (SLN) mapping in combination with surgical biopsy is an emerging technique for use in the early stages of cervical cancer. The purpose of this study was to evaluate the technique in a series of 40 consecutive women with early stage cervical cancer. METHODS: Forty patients with early stage cervical cancer [FIGO stage IA2 (2), IB1 (34), IB2 (1) or IIA (3)] were referred for radical hysterectomy with pelvic lymphadenectomy. Patients were submitted to preoperative lymphoscintigraphy (four 99mTc-nanocolloid injections around the tumour) and intraoperative SLN detection. Hand-held or laparoscopic gamma probes were used to locate SLNs during surgery. RESULTS: The mean number of SLNs was 2.5 per patient (interiliac 49%, external iliac 19%). Of the total of 99 SLNs, six, in four women, showed metastases (all 68 non-SLNs removed were negative). In the other 36 patients, all the removed lymph nodes (sentinel and non-sentinel) were negative (0% false negative rate). During the follow-up (median 25 months), only two patients presented distant metastases: one died 6 months after surgery (two of three SLNs positive, both hot and blue), while the second patient is alive 4 years after surgery (lung metastasis, no isotope drainage, negative blue SLN). The survival rate was 95% and disease-free survival, 97%. CONCLUSION: SLN surgical biopsy based on lymphoscintigraphy and blue dye is a feasible and useful technique to avoid lymph node dissection in the early stages of cervical cancer. It has a high negative predictive value, can be incorporated into clinical routine (laparoscopy or open surgery) and is close to achieving validation in this setting.

[Value of brain perfusion SPECT in the follow-up of patients surgically treated for chronic adult hydrocephalus syndrome]. / Valor del SPECT de perfusión cerebral en el seguimiento del tratamiento quirúrgico de pacientes con hidrocefalia crónica del adulto.

OBJECTIVE: The aim of this study was to characterize regional cerebral blood flow in patients with Adult Hydrocephalus Syndrome (AHS) and to evaluate the changes in brain perfusion after surgical derivation treatment. PATIENTS AND METHODS: 20 patients with AHS (age: 72 +/- 14, 12 men) were studied before and six months after surgery. All patients underwent a brain perfusion SPECT (99mTc-HMPAO) prior to surgery and at 6 months post-surgery. Semi-quantitative analysis was done for brain uptake: 0=Normal, 1=Mild, 2=Moderate, 3= Severe, 4=No uptake. The severity of ventricular dilatation was assessed by classifying the intensity and extension of subcortical defects: 0=Normal, 1=Mild, 2=Moderate, 3=Severe. The scores of the pre- and post-surgical studies were compared using the Student-t test. RESULTS: A global reduction of brain uptake was observed (mean score 12.85), mainly in frontal, parietal and temporal lobes, with a significant improvement in post surgical studies (mean score 6, p<0,001). After surgery, 16 (80%) of the 20 patients improved brain uptake. In relationship to subcortical uptake, 5 patients showed mild defects, 9 moderate defects and 6 patients presented severe uptake reduction. In post-surgical studies 15 (75%) patients improved almost one degree in the subcortical score and 65% of the patients showed a normal or mild subcortical uptake reduction. CONCLUSIONS: Brain perfusion SPECT is useful in patients with AHS, detecting brain perfusion defects and evaluating cerebral blood flow improvement after shunt operation.

[Diagnostic accuracy of tomographic myocardial imaging for evaluation of aortocoronary graft patency]. / Eficacia de la tomogammagrafía miocárdica en la valoración de la permeabilidad de los injertos aortocoronarios.

INTRODUCTION AND OBJECTIVES: Conventional ergometry has limitations in the evaluation of coronary artery bypass graft patency. The aim of the present study was to determine the efficacy of exercise single photon emission tomography with 99mTc-compounds for the diagnosis of coronary artery bypass grafts disease. PATIENTS AND METHODS: The state of sixty-seven coronary artery bypass grafts (31 with mammary artery, 36 with safein vein; 35 to left descending anterior artery, 15 to circumflex and 17 to right coronary artery) were analyzed retrospectively in 38 patients (mean age 63+/-8.7; 35 men). The time that elapsed between the coronary surgery and the exercise tomography was 9,7 years. In 16 cases, exercise tomography was performed with 99mTc-MIBI and in the 22 remaining with 99mTc-tetrofosmin. In 6 cases, dipiridamol was administred simultaneously during an insufficient exercise test. RESULTS: Sensitivity (73.1%), specificity (93%), positive predictive value (86.3%), negative predictive value (84.4%), global value (85%), positive likelihood ratio (10.4) and negative likelihood ratio (0.29) of exercise tomography were significantly (p<0.01) better than those obtained with the exercise test alone (53.8%, 43.6%, 38.9%, 58. 6%, 47.7%, 0.95 and 1.06, respectively). CONCLUSIONS: Exercise tomography with 99mTc-compounds is a highly effective for the detection of coronary artery bypass grafts disease.

[Perfusion tomographic scintigraphy and coronary angiography as complementary studies for the therapy decision for patients with ischemic cardiopathy]. / La tomogammagrafía de perfusión y la coronariografía como exploraciones complementarias en la decisión terapéutica de pacientes con cardiopatía isquémica.

BACKGROUND: The aim of the present study was to assess the value of tomographic perfusion scintigraphy as a complement to coronary arteriography in the therapeutic management of patients admitted to the hospital for treatment of unstable ischaemic heart disease. METHODS: A review was carried out of the discharge report of 100 consecutive patients (mean age 58 years, 19 females) in which there was a mention of having taken a therapeutic decision on the basis of coronary angiography and tomographic perfusion scintigraphy with 99m-technetium isonitriles under exercise and/or dipyridamole. In 90% of instances the study was performed during drug therapy after the patient had remained stable for at least 3 days. The indication of the studies and the type of therapy was made by the attending physician. Concordance between both studies was said to exist when both pointed to the same type of therapeutic approach, either medical treatment (nonsevere stenosis on coronary arteriography with mild ischaemia on scintigraphy) or revascularization (severe stenosis with moderate or severe ischaemia in tomographic scintigraphy). Discordance was said to be present when ischaemia was mild with severe stenosis on coronary angiography. RESULTS: In 80 patients there was concordance between both studies regarding the subsequent therapeutic approach (medical treatment in 32 and revascularization in 48 [25 coronary angioplasty and 23 bypass surgery]). In the patients with discordance (n:20) medical treatment was decided in 14 patients on the basis of mild ischaemia with significant angiographic stenosis, and in only 6 patients revascularization (angioplasty in 5 and bypass surgery in 1) was indicated, based on the severity of coronary stenosis even if the ischaemia apparent on the scintigraphy was mild. CONCLUSIONS: Therefore, in 80% of patients admitted for unstable coronary artery disease there was a concordance between the results of tomographic scintigraphy and coronary angiography, when both studies were indicated to select the most appropriate therapeutic modality. In the 20% of discordant cases the attending physician decided on a conservative strategy in most cases, as no significant enough perfusion defect was shown on scintigraphy in spite of severe coronary artery stenosis.

[Radioactive isotope evaluation of apical seal of two types of thermoplasticized gutta-percha at high and low temperature]. / Evaluation à l'aide d'isotopes radio-actifs de l'étanchéité apicale de deux types de gutta-percha thermoplastifiée à haute et basse température.

The aim of this study was to evaluate the apical seal obtained using root canal filling techniques based on low and high temperature thermoplasticized gutta-percha, comparing them with the lateral condensation technique. The roots of thirty permanent upper canines and incisors were used, they were instrumented and obturated using each of the above techniques. The apical leakage was measured using a radioactive isotope and an external detection technique. No significant difference was found in the apical seal obtained by the three techniques.