Role of the clinical radiopharmacist in patient safety during myocardial perfusion imaging with vasodilator stress agents.

AIM: To assess the radiopharmacist's role in a multidisciplinary team focused on the contraindications of regadenoson in order to ensure the safe use of pharmacologic vasodilator stress agents in patients undergoing SPECT-MPI. METHODS: We ambispectively studied its safe use in 1905 patients (54.1% female, mean age: 66.6±11.7 years, range: 20-95 years). Sex, age, medical history, medications, drug allergies, and contraindications for stress testing were registered together with recommendations for the nuclear physician in charge. RESULTS: Detected contraindications and corresponding recommendations were as follows: risk factors for QTc interval prolongation 7.5% - measurement of QTc interval previously to test and monitor ECG; prior stroke or TIA 4.2% - consider carotid stenosis assessment; salicylates/sulfonamides allergy 3.1% - use 99mTc-sestamibi; epilepsy or risk factors for seizures 2.4% - use of adenosine or reconsider test indication; systemic corticosteroid therapy for severe COPD 1.3% - reassessment of patient's condition; acute exacerbation of COPD 0.8% - defer test until acute episode is over; severe asthma 0.4% - do not perform test; methylxanthine ingestion 0.3% - avoid consumption previously; other 6.1% - evaluation of other contraindications. No contraindications were detected in 73.6% of patients. The test was canceled due to absolute contraindications in 2.9% of the requests. CONCLUSIONS: Working in a systematic way, the radiopharmacist was able to detect a high number of issues related to regadenoson, with one out of four patients presenting some clinical contraindication. The recommendations given by the radiopharmacist were well accepted by the nuclear physicians who changed their approach contributing to increase the safety of patients referred for MPI.

Assessment of pulmonary embolism related to active SARS-CoV-2 infection in pregnant women.

AIM: To analyze a sample of pregnant patients who underwent pulmonary perfusion scintigraphy to rule out suspicion of pulmonary embolism (PE) during the acute COVID-19 infection hospitalization period in our hospital. MATERIAL AND METHODS: SPECT scintigraphy with a reduced dose (111MBq) of 99mTc-macroaggregated albumin was performed in all the patients (n=5). The images obtained were interpreted by comparing the findings with the radiological images according to the PISAPED criteria. RESULTS: Only one of the 5 patients was diagnosed with PE. Two patients showed pathological scintigraphy findings attributable to radiological alterations due to COVID-19 pneumonia, and the other two had normal pulmonary perfusion. CONCLUSION: Given the non-specific features of the clinical manifestations and d-dimer values ​​in COVID-19, as well as their similarity to those of PE, pulmonary perfusion scintigraphy plays a crucial role in the screening of PE in these patients due to its high sensitivity and lower irradiation compared to CT. Despite the limited number of patients, the results obtained have special relevance due to the absence of scientific publications in this group of patients within the exceptional context of the COVID-19 pandemic.

[Nuclear Cardiology in the COVID-19 pandemic]. / La cardiología nuclear en la pandemia COVID-19.

SARS-CoV-2 infection has a very important relationship with cardiovascular disease. Since the beginning of the pandemic, a close relationship has been observed between cardiovascular comorbidity and a worse prognosis in COVID-19 patients. The study of the pathophysiology of SARS-CoV-2 infection and cardiovascular disease suggests several concomitant hypotheses: direct myocardial damage by the virus, hypoxemia secondary to respiratory failure, inflammatory response to infection and/or thromboembolic phenomena. Cardiovascular damage can manifest in the acute phase of infection with acute myocardial infarction, myocarditis, arrhythmias..., during this phase Nuclear Cardiology procedures have not played a determining role in the diagnosis and management of these patients. On the other hand, in the subacute phase of the infection and in the post-acute COVID syndrome, Nuclear Cardiology seems to shed light on what happens in the cardiovascular system in this phase of the disease.The COVID-19 pandemic has represented a great challenge for health systems, with a significant reduction in non-urgent diagnostic procedures with the aim of reducing the risk of transmission to patients and health personnel. Nuclear Cardiology has not been an exception. In addition to the prioritization of urgent/non-deferrable procedures and general screening, hygiene and distance measures, the main organizations and scientific societies of Nuclear Medicine and Nuclear Cardiology released recommendations and guidelines for safe practice, introducing significant changes in myocardial perfusion SPECT protocols.

Cardiac scintigraphy with 99mTc-diphosphonates in cardiac amyloidosis. / Gammagrafía cardíaca con 99mTc-difosfonatos en la amiloidosis cardíaca.

Transthyretin cardiac amyloidosis (ATTR) has traditionally been considered a rare, difficult-to-diagnose and untreatable disease. However, its prevalence is known to be greater than what was previously thought, non-invasive diagnostic methods are available, and that effective treatments are emerging. In this context, cardiac scintigraphy (CS) with 99mTc-labelled diphosphonates has aroused a noticeable surge in interest by demonstrating high sensitivity and specificity for the reliable, non-invasive diagnosis of ATTR. By way of a guide, this article aims to identify the critical components in the performance of CS that are useful in everyday clinical practice and, thus, help specialists use optimal radiopharmaceuticals, obtain the most appropriate images, interpret the results thereof, and acquaint themselves with those clinical scenarios in which it is convenient to perform CS.

Effect of cardiac resynchronization therapy on septal perfusion and septal thickening: Association with left ventricular function, reverse remodelling and dyssynchrony.

BACKGROUND: We evaluated the effect of cardiac resynchronization therapy (CRT) on septal perfusion and thickening at 6 months post implantation assessed on Tc99m-MIBI Gated myocardial perfusion SPECT (GMPS).We also studied the association of change in septal perfusion and thickening with primary outcome defined as at least one [improvement in ≥1NYHA class, left ventricular ejection fraction (LVEF) by ≥ 5%, reduction of end-systolic volume (ESV) by ≥ 15%, and improvement ≥ 5 points in Minnesota living with heart failure questionnaire (MLHFQ)]. METHOD: One hundred and five patients underwent clinical and GMPS evaluation before and at 6 months post CRT. RESULT: Post CRT there was significant improvement in mean normalized septal perfusion uptake and in septal thickening (P value = 0.001, both). There was no significant relation between improvement in septal perfusion and primary outcome. However, improvement in septal thickening was statistically significant with favorable primary outcome (P = 0.001).There was no significant correlation between improvement of septal perfusion and improvement in LVEF, reduction in End diastolic volume (EDV), ESV, and Left ventricular Dyssynchrony (LVD). But, there was significant correlation between improvement of septal thickening and these parameters. CONCLUSION: Improvement in septal thickening was associated with reverse remodeling, improvement in LVEF, and reduction of LVD.

Cardiac sympathetic innervation scintigraphy with 123I-meta-iodobenzylguanidine. Basis, protocols and clinical applications in Cardiology. / Gammagrafía de inervación simpática cardiaca con 123I-metayodobencilguanidina. Fundamento, protocolos y aplicaciones clínicas en Cardiología.

Imaging of cardiac sympathetic innervation is only possible by nuclear cardiology techniques and its assessment is key in the evaluation of and decision-making for patients with cardiac sympathetic impairment. This review includes the basis of cardiac sympathetic scintigraphy with 123I-meta-iodobenzylguanidine (123I-MIBG), recommended protocols, patient preparation, image acquisition and quantification, reproducibility, dosimetry, etc., and also the clinical indications for cardiac patients, mainly with regard to heart failure, arrhythmia, coronary artery disease, cardiotoxicity, including its contribution to establishing the indication for and monitoring the response to implantable cardiac devices, pharmacological treatment, heart transplantation and other.

Safety of regadenoson in patients with severe chronic obstructive pulmonary disease.

OBJECTIVE: To assess the safety of regadenoson, a selective agonist of A2A adenosine receptors, combined with low-level exercise in subjects with severe chronic obstructive pulmonary disease (COPD), referred for myocardial perfusion imaging (MPI). METHODS: We studied prospectively 12 male patients with severe COPD. Stress was 4min of low-level exercise with bolus injection of regadenoson (0.4mg) at 1.5min, followed by (99m)Tc-MPI agent injection. Demographics, medical history, lung medications, adverse events, oxygen saturation (SatO2), MPI findings for coronary artery disease (CAD), and changes in systolic blood pressure (SBP), and heart rate (HR) were registered. RESULTS: The observed adverse event profile of regadenoson was similar to that of patients with mild-moderate COPD. There was no clinical exacerbation of COPD. Adverse events were self-limiting: dyspnea (33.3%), fatigue (25.0%), chest pain, headache (16.7%, respectively), and gastrointestinal discomfort, dry mouth, flushing, feeling hot and dizziness (8.3%, respectively). 25.0% of patients did not report any symptoms. We observed significant increases in SBP and HR from baseline (142.6mmHg±22.3 vs 152.5mmHg±18.5, and 80 b.p.m.±18 vs 105 b.p.m.±22, respectively; p<0.05). CONCLUSIONS: Regadenoson combined with low-level exercise is safe and well tolerated in stable patients with severe COPD undergoing MPI.

Preload dependence of gated cardiac SPECT-derived ventricular volumes in hemodialysis patients.

BACKGROUND: In hemodialysis (HD) patients, the intravascular volume expansion of the pre-HD state leads to a high preload. We aim to examine its effect on myocardial perfusion gated SPECT (MPGS)-derived left ventricular (LV) volumes. METHODS: The study comprised 50 end-stage renal disease (ESRD) patients on HD with normal 2-day stress/rest MPGS performed for kidney transplantation risk assessment. Patients (pts) comprised 23 men/27 women, with mean age of 59.4 ± 7.1 years. The time elapsed from the last HD session in hours was calculated on both days, and patients were classified according to whether it was higher (group A: 19 pts), lower (group B: 27 pts), or equal (group C: 4 pts) on the stress vs the rest day. End-diastolic, end-systolic volumes (EDV, ESV), and left ventricular ejection fraction (LVEF) were determined using QGS™ software. Transient ischemic dilation (TID) ratios were derived from the nongated images using QPS™ software. RESULTS: Volumes were significantly higher at stress in group A, at rest in group B, and similar in group C. TID ratios were significantly higher in group A vs groups B and C. CONCLUSIONS: MPGS-derived ventricular volumes are preload dependent. The high preload of the pre-HD state may mimic ischemic TID if occurring on the stress day and create confusion if coinciding with the rest day.

[Quantitative salivary gland scintigraphy in head and neck cancer patients following radiotherapy]. / Gammagrafía salival cuantitativa en pacientes con cáncer de cabeza y cuello tratados con radioterapia.

OBJECTIVE: To assess the role of quantitative salivary gland scintigraphy (SGS) in the detection of functional impairment of salivary glands in patients with head and neck cancer treated with radiotherapy (RT). MATERIAL AND METHODS: We studied 19 patients (17 men), mean age 62.4 years (44-75). Three studies were performed to each patient: baseline, 3 and 18 months after RT. SGS was acquired for 25 minutes following injection of 3.7 MBq/kg of (99m)Tc-pertechnetate with lemon juice at the end of minute 15. Excretion fraction (EF), counts per minute/pixel/MBq (CMPM) and uptake percentage were obtained from time-activity curves from ROIs placed over parotid (PG) and submandibular glands (SMG) and related to the doses received by the PG. RESULTS: EF showed a significant reduction from the baseline to the 3 months study (p<0.001) for the PG and SMG and from the baseline to the 18 months study for the SMG (p<0.001). A significant improvement of EF was seen from the 3 months to the 18 months study for the PG (p<0.05). CMPM did not change significantly from the baseline to the 3 months and 18 months studies for the PG and showed a significant reduction (p<0.01) for the SMG from the baseline to 18 months study. The uptake percentage did not change significantly between studies. A moderate association was observed between the doses to PG and the 3m study parameters. CONCLUSIONS: EF was more sensitive than uptake in assessing post-RT impairment of salivary function. In addition, it reflected functional recovery of parotid glands over time.

[99mTc-labelled antigranulocyte anibody fragment Fab scintigraphy (sulesomab, leukoscan) and three-phase bone scintigraphy in the study of painful hip and knee prosthesis]. / Gammagrafía con fragmentos Fab' antigranulocitos-99mTc (sulesomab, leukoscan) y ósea en tres fases en el estudio de las prótesis de cadera y rodilla dolorosas.

We aim to assess the diagnostic utility of the combination of a three phase bone scintigraphy (3FBS) and scintigraphy with Fab'antigranulocyte fragments-99mTc (Sulesomab, Leukoscan) in patients with painful joint replacements. We studied 29 patients (22 women and 7 men with mean age 64 years) with knee (15) and hip (14) prosthesis. Scintigraphy was performed with a Siemens Orbiter 75 gammacamera with all purpose collimator. 3FBS was performed as usual with 740 MBq of MDP-99mTc. Sulesomab images were obtained at 1 and 4 hours following injection of 740 MBq, with 300,000 cts per view (knee) and 500,000 cts per view (hip). Both scintigraphic studies were interpreted visually by two nuclear medicine physicians with a 0, 1, 2, 3 score corresponding to normal or mild, moderate or intense hyperactivity respectively. Interpretation criteria for bone infection was Sulesomab uptake grade 2 or 3 in a moderate or large sized area, with congruent hyperactivity on the bone scan. Grade 1 uptake with Sulesomab was considered nonspecific associated to nonseptic conditions. The frequent pattern of uptake in synovial femoral tissue (cap shape sign) in knee prosthesis was considered nonspecific. Diagnostic confirmation procedures were surgery and culture (9) and follow-up (20). All six septic joints were correctly identified. A false positive result was obtained in a case of mechanical loosening in the knee. Negative studies were very helpful in the exclusion of infection. Our conclusion is that sensitivity is high, 100%, and that a normal or grade 1 Sulesomab image makes the presence of infection improbable.

Detection of inflammation/infection with human polyclonal immunoglobulin G labelled with 99Tcm.

Radiolabelled human polyclonal immunoglobulin G (IgG) has been successful in identifying inflammatory/infectious processes in human and animal models. We studied 71 patients with suspicion of inflammation of varied origin and location (44 of musculoskeletal location and 27 other) using 99Tcm. IgG images correctly identified 21/22 inflammatory sites of musculoskeletal origin and only 4/14 sites of soft-tissue location. Five false negative studies corresponded to granulomatous processes, three of them tuberculosis. Four false positive studies were obtained in the musculoskeletal group corresponding to three synovial tumours and a Charcot joint. No false positive results were seen in the soft tissue group. 99Tcm-IgG performs well in the identification of bone-joint lesions and rules out non-inflammatory conditions (with the important exception of tumours). The role of 99Tcm-IgG in soft-tissue inflammatory sites, especially in highly vascular organs is inferior, with a high yield of false negative studies. Granulomatous lesions probably represent situations of low or absent IgG uptake.

[Renal hypertrophy studied by techniques of nuclear medicine in post-nephrectomy patients]. / Estudio de la hipertrofia renal compensadora con técnicas de medicina nuclear en pacientes sometidos a nefrectomía.

Study of group of 61 patients, nephrectomized as a result of various diseases and who before and three months after surgery underwent blood pressure, effective renal plasma flow (EPFF) and unilateral renal function determinations in order to verify the compensating ability of the remaining kidney. Effective renal plasma flow was determined by a single injection and removal of six serial blood samples with 125-I-Hippuran. Unilateral renal function was determined from the relative uptake of 99mTc-DMSA 24 hours after injection. The patients were divided into four groups according to their overall and unilateral renal function as well as the presence or absence of hypertension. Patients with normal EPFF and symmetrical renal function showed a significantly increase in the function of the remaining kidney after surgery (p < 0.001). Patients with normal or slightly reduced EPFF (< 10%) and highly asymmetrical unilateral function as well as those with decreased EPFF (> 10%) and symmetrical or asymmetrical unilateral renal function did not increased the function of the remaining kidney after nephrectomy, and hypertensive patients whose blood pressure returned to normal values after nephrectomy had a decreased function of the remaining kidney after surgery (< 0.001). It is concluded that it is possible to predict the functional behaviour of the remaining kidney after nephrectomy, and that the compensating ability will basically depend on the previously existing (overall and unilateral) renal function as well as the presence or absence of hypertension.

Myocardial damage following coronary bypass surgery: assessment with antimyosin antibody uptake.

To assess the role of 111In antimyosin antibody (AbAm) in the delineation of myocardial damage following coronary bypass surgery, we studied 51 consecutive patients who underwent coronary surgery, 27 of whom had a history of prior myocardial infarction. All patients underwent a diagnostic protocol comprising: (1) 99Tcm pyrophosphate (PYP) and AbAm injection 48 h after surgery (AbAm imaging 24 and 48 h post-injection) (myocardial/background and myocardial/lung ratios were obtained respectively from the computer image); (2) Radioimmunoassay (RIA) serum CK-B levels from samples obtained immediately before surgery, and 24 and 48 h later; (3) clinical and ECG follow-up. Twenty-five patients showed positive AbAm studies, 10 had positive PYP images, and 21 had CK-B levels above normal limits at 24 h. One patient with abnormal AbAm, PYP and CK-B studies had new Q waves on the ECG after surgery. This patient was considered to have sustained a peri-operative myocardial infarction. The large number of positive AbAm studies probably reflects myocardial damage frequently associated with coronary bypass surgery.

Noninvasive radioisotopic diagnosis of acute heart rejection.

In a prospective protocol for noninvasive diagnosis and follow-up of acute heart rejection 162 examinations were performed in 36 patients who underwent heart transplantation. The follow-up period ranged from 15 days to 44 months. The protocol comprised multiple gated acquisition ventriculography with albumin labeled with 99mTc (740 MBq), acquired using a forward/backward by thirds framing mode, 32 frames/cycle, and 10 million total counts. Parameters of left ventricular diastolic function were analyzed. Antimyosin antibody labeled with indium 111 (74 MBq) was injected, and myocardium/lung uptake ratios were obtained at 48 hours in counts per pixel. Endomyocardial biopsy was performed in all patients within 48 hours. The results were evaluated by comparison of mean values of each parameter and global and individual correlation analysis in relation to the presence or absence of rejection and treatable (moderate or severe) or nontreatable (mild or absent) rejection. Antimyosin and diastolic function parameters showed significant differences (p less than 0.001) between patients with and without rejection and between patients with treatable and nontreatable rejection. Global correlation with biopsy existed (p less than 0.05) for antimyosin (r = 0.75), average filling rate (r = 0.61), and peak filling rate (r = 0.56). Individual correlation exhibited significance in all patients only for antimyosin (r = 0.78 to 0.98). In eight patients average filling rate also showed significant correlation (r = 0.65 to 0.88). In conclusion, these results provide a noninvasive diagnosis of cardiac allograft rejection episodes and allow an accurate selection between treatable and nontreatable rejection. Individual patient follow-up is possible with antimyosin. The study of diastolic function is also useful in this setting.

Diagnosis of brain death: superiority of perfusion studies with 99Tcm-HMPAO over conventional radionuclide cerebral angiography.

The use of technetium-99m hexamethyl-propyleneamine oxime (99Tcm-HMPAO) in the diagnosis of brain death has been evaluated in 41 studies of 37 patients with severe brain injury, who were under the effect of drugs or when other diagnostic methods were equivocal. HMPAO studies were compared with conventional radionuclide angiography performed simultaneously by intravenous administration of HMPAO as a bolus. The ages of patients ranged from 4 months to 75 years. Dynamic flow images and 5-min static uptake images were acquired following bolus injection of 555 Mbq of 99Tcm-HMPAO. All patients showing no brain uptake were confirmed as brain-dead by standard clinical criteria, with no contradictory cases in the static study. In addition, all patients who were not brain-dead showed HMPAO uptake at least in the brainstem. Dynamic flow images were equivocal in five patients, four of whom had no uptake on static images and clinically confirmed brain death. In addition, two other cases showed "mismatched" dynamic and static images: in one case no perfusion was observed on flow images but uptake restricted to the posterior fossa was seen on static images; the other case showed perfusion on the dynamic study and static imaging revealed hemispheric uptake with no posterior fossa uptake. Static perfusion 99Tcm-HMPAO studies offer advantages over conventional brain scintigraphy, better results being due to adequate assessment of posterior fossa activity and avoiding equivocal studies.

Immunoscintigraphy of lung cancer using 111In-labelled antiCEA F023C5-F(ab')2 fragments.

Forty-one patients with known lung carcinoma or suspicion of bearing this disease were studied with 111In-antiCEA F023C5-F(ab')2. Five patients with positive results were further studied to assess in vivo specificity using 111In-4C4-F(ab')2 (MoAb antihepatitis). Immunoscintigraphic results have been compared to immunohistochemistry in 16 patients. Tumour visualization with non-specific MoAb was present in all five patients although the maximum tumour/background (T/B) ratio obtained was 1.51. Therefore a 'specificity criterion' has been applied to examinations performed with MoAb antiCEA. There was considered to be a positive result when the T/B ratio was greater than 1.60. Results obtained in this way for thoracic lesions were 25/34 true positive (TP) (73%) and 6/7 true negative (TN) (86%). When studies were analysed visually only, the results were 32/34 TP (94%) and 3/7 TN (43%). In addition, immunoscintigraphic results are more concordant with immunohistochemical results when the specificity criterion is applied. In metastatic lesions results were 9/13 TP (69%) with only 1/3 TP (33%) for liver metastasis (anatomic site of lowest detection ability). SPECT imaging did not improve results over planar images, although it clearly contributed to a better anatomic location of lesions. The constant presence of non-specific uptake in thoracic lesions makes it necessary to establish a T/B ratio limit in order to obtain adequate specificity with the immunoscintigraphic technique.