Home treatment of patients with small to medium sized acute pulmonary embolism.

Most patients with acute pulmonary embolism (PE) are still treated as inpatients. This is a retrospective cohort study of patients with acute PE, diagnosed using V/P SPECT between 2007 and 2011. Patients were treated at home if they were hemodynamically stable, did not require oxygen or parenteral analgetics, had no contraindications to anticoagulant treatment and V/P SPECT showed an extension of the PE of less than 40%. The aim of the study was to evaluate the efficacy and safety of home treatment with our algorithm. During the study period 416 outpatients were diagnosed with acute symptomatic PE of whom in total 260 (62.5%) were discharged home from the emergency unit and another 47 (11%) within 24 h from admission. During 3 months follow-up one (0.3%) patient had a recurrent thrombotic event. Eleven (3.6%) patients had a major or clinically relevant bleed and the overall mortality was 2% (n = 6). There were no PE-related mortality. Home treatment should be considered and is safe in the majority of hemodynamically stable outpatients with small to medium size PE, quantified using V/P SPECT.

EANM guidelines for ventilation/perfusion scintigraphy : Part 2. Algorithms and clinical considerations for diagnosis of pulmonary emboli with V/P(SPECT) and MDCT.

As emphasized in Part 1 of these guidelines, the diagnosis of pulmonary embolism (PE) is confirmed or refuted using ventilation/perfusion scintigraphy (V/P(SCAN)) or multidetector computed tomography of the pulmonary arteries (MDCT). To reduce the costs, the risks associated with false-negative and false-positive diagnoses, and unnecessary radiation exposure, preimaging assessment of clinical probability is recommended. Diagnostic accuracy is approximately equal for MDCT and planar V/P(SCAN) and better for tomography (V/P(SPECT)). V/P(SPECT) is feasible in about 99% of patients, while MDCT is often contraindicated. As MDCT is more readily available, access to both techniques is vital for the diagnosis of PE. V/P(SPECT) gives an effective radiation dose of 1.2-2 mSv. For V/P(SPECT), the effective dose is about 35-40% and the absorbed dose to the female breast 4% of the dose from MDCT performed with a dose-saving protocol. V/P(SPECT) is recommended as a first-line procedure in patients with suspected PE. It is particularly favoured in young patients, especially females, during pregnancy, and for follow-up and research.

EANM guidelines for ventilation/perfusion scintigraphy : Part 1. Pulmonary imaging with ventilation/perfusion single photon emission tomography.

Pulmonary embolism (PE) can only be diagnosed with imaging techniques, which in practice is performed using ventilation/perfusion scintigraphy (V/P(SCAN)) or multidetector computed tomography of the pulmonary arteries (MDCT). The epidemiology, natural history, pathophysiology and clinical presentation of PE are briefly reviewed. The primary objective of Part 1 of the Task Group's report was to develop a methodological approach to and interpretation criteria for PE. The basic principle for the diagnosis of PE based upon V/P(SCAN) is to recognize lung segments or subsegments without perfusion but preserved ventilation, i.e. mismatch. Ventilation studies are in general performed after inhalation of Krypton or technetium-labelled aerosol of diethylene triamine pentaacetic acid (DTPA) or Technegas. Perfusion studies are performed after intravenous injection of macroaggregated human albumin. Radiation exposure using documented isotope doses is 1.2-2 mSv. Planar and tomographic techniques (V/P(PLANAR) and V/P(SPECT)) are analysed. V/P(SPECT) has higher sensitivity and specificity than V/P(PLANAR). The interpretation of either V/P(PLANAR) or V/P(SPECT) should follow holistic principles rather than obsolete probabilistic rules. PE should be reported when mismatch of more than one subsegment is found. For the diagnosis of chronic PE, V/P(SCAN) is of value. The additional diagnostic yield from V/P(SCAN) includes chronic obstructive lung disease (COPD), heart failure and pneumonia. Pitfalls in V/P(SCAN) interpretation are considered. V/P(SPECT) is strongly preferred to V/P(PLANAR) as the former permits the accurate diagnosis of PE even in the presence of comorbid diseases such as COPD and pneumonia. Technegas is preferred to DTPA in patients with COPD.

Ventilation/Perfusion SPECT for diagnostics of pulmonary embolism in clinical practice.

AIM: The aim of this retrospective study is to illustrate clinical utility and impact of pulmonary embolism (PE) diagnostics of up to date Ventilation/Perfusion SPECT (V/P (SPECT)) applying holistic interpretation criteria. MATERIAL AND METHODS: During a 2-year period 2328 consecutive patients referred to V/P(SPECT) for clinically suspected PE were examined. Final diagnosis was established by physicians clinically responsible for patient care. To establish the performance of V/P(SPECT) negative for PE, patients were followed up by medical records for 6 months. RESULTS: Ventilation/Perfusion SPECT was feasible in 99% of the patients. Data for follow-up were available in 1785 patients (77%). PE was reported in 607 patients (34%). Normal pattern was described in 420 patients (25%). Pathology other than PE such as a pneumonia, left heart failure, obstructive lung disease, tumour was described in 724 patients (41%). Report was nondiagnostic in 19 patients (1%). Six cases were classified as falsely negative because PE was diagnosed at follow-up and was fatal in one case. Six cases were classified as falsely positive because the clinician decided not to treat. In 608 patients with final PE diagnosis, 601 patients had positive V/P(SPECT) (99%). In 1177 patients without final PE diagnosis 1153 patients had negative V/P(SPECT) (98%). CONCLUSIONS: Holistic interpretation of V/P(SPECT,) yields high negative and positive predictive values and only 1% of nondiagnostic findings and was feasible in 99% of patients. It is a responsibility and a challenge of nuclear medicine to provide optimal care of patients with suspected PE by making V/P(SPECT) available.

Identifying the heterogeneity of COPD by V/P SPECT: a new tool for improving the diagnosis of parenchymal defects and grading the severity of small airways disease.

INTRODUCTION: Airway obstruction and possible concomitant pulmonary diseases in COPD cannot be identified conventionally with any single diagnostic tool. We aimed to diagnose and grade COPD severity and identify pulmonary comorbidities associated with COPD with ventilation/perfusion single-photon emission computed tomography (V/P SPECT) using Technegas as the functional ventilation imaging agent. METHODS: 94 COPD patients (aged 43-86 years, Global Initiative for Chronic Obstructive Lung Disease (GOLD) stages I-IV) were examined with V/P SPECT and spirometry. Ventilation and perfusion defects were analyzed blindly according to the European guidelines. Penetration grade of Technegas in V SPECT measured the degree of obstructive small airways disease. Total preserved lung function and penetration grade of Technegas in V SPECT were assessed by V/P SPECT and compared to GOLD stages and spirometry. RESULTS: Signs of small airway obstruction in the ventilation SPECT images were found in 92 patients. Emphysema was identified in 81 patients. Two patients had no signs of COPD, but both of them had a pulmonary embolism, and in one of them we also suspected a lung tumor. The penetration grade of Technegas in V SPECT and total preserved lung function correlated significantly to GOLD stages (r=0.63 and -0.60, respectively, P<0.0001). V/P SPECT identified pulmonary embolism in 30 patients (32%). A pattern typical for heart failure was present in 26 patients (28%). Parenchymal changes typical for pneumonia or lung tumor were present in several cases. CONCLUSION: V/P SPECT, using Technegas as the functional ventilation imaging agent, is a new tool to diagnose COPD and to grade its severity. Additionally, it revealed heterogeneity of COPD caused by pulmonary comorbidities. The characteristics of these comorbidities suggest their significant impact in clarifying symptoms, and also their influence on the prognosis.

Ancillary findings assessed by ventilation/perfusion tomography. Impact and clinical outcome in patients with suspected pulmonary embolism.

UNLABELLED: Ventilation/perfusion tomography (V/P SPECT) is a recommended method for diagnosing and follow-up of pulmonary embolism (PE). Moreover, it is possible to recognize other pathologies in addition to PE, such as pneumonia, COPD and left heart failure (LHF). The objective of this prospective study was to identify frequency of ancillary findings among patients with suspected PE. Patients, material, method: 331 consecutive patients with suspected PE were examined and classified with V/P SPECT. Patients were followed up clinically and by means of other laboratory tests. RESULTS: 80 patients had a normal V/P SPECT and no clinical consequences in the follow-up. PE had 104 patients: 23 of them had also additional findings. Among the remaining 147 patients, pneumonias were shown in 82, acute in 75 patients and 7 had chronic post inflammatory state. COPD was present in 42 patients, in 3 combined with pneumonia. Sign of LHF was observed in 10: in 7 the acute LHF diagnosis was established, 3 were classified as having a chronic cardiopulmonary disease. Furthermore, in 16 patients, the V/P pattern was suggestive of a tumour. The clinical outcomes were 6 lung tumours, 3 empyema, one sarcoidosis, 2 were unclarified and 4 were lost in the follow-up. CONCLUSION: V/P SPECT identifies a high prevalence of other cardiopulmonary diseases among patients with a clinical suspicion of PE. Ancillary findings with V/P SPECT clarified patients' symptoms and had an impact on the treatment. These findings were verified by a clinical outcome by the follow-up over three months.

Dynamic indium-111-pentetreotide scintigraphy in breast cancer.

UNLABELLED: The efficacy of imaging breast cancer with 111In-pentetreotide (somatostatin receptor scintigraphy) was evaluate before surgery. METHODS: Seventy-one whole-body scintigrams in 24 patients with known breast cancer and 24 whole-body scintigrams in 8 controls were obtained at 0.5, 5 and 24 hr after intravenous injection of 110 MBq 111In-pentetreotide. Anterior and posterior projection images were acquired simultaneously. SPECT of the thorax was performed at 5 or 24 hr after injection in all breast cancer patients. The specimens were imaged immediately after surgery and the distribution of pentetreotide was assessed qualitatively and quantitatively. RESULTS: Somatostatin receptor-positive tumors were found in 18/24 patients with breast cancer. Pentetreotide uptake was significantly greater in breast cancer patients compared to control patients. In all patients with positive images, the early scintigram (0.5 hr) showed abnormal uptake. It was possible to delineate three different dynamic patterns. Increased uptake was visually most distinct at each time (9 patients). Moreover, bilaterally increased pentetreotide uptake was observed in 10/18 true-positive patients (in 8 at each time and in 2 patients only at 5 hr), but only one patient had a known bilateral tumor. CONCLUSION: We found higher incidence of somatostatin receptors in patients with breast cancer than in the control group. Moreover, bilaterally increased pentetreotide uptake in clinically unilateral disease was an unexpected finding.

Comprehensive ventilation/perfusion SPECT.

UNLABELLED: Lung scintigraphy is the primary tool for diagnostics of pulmonary embolism. A perfusion study is often complemented by a ventilation study. Intermediate probability scans are frequent. Our goal was to develop a fast method for tomographic ventilation and perfusion scintigraphy to improve the diagnostic value of lung scintigraphy. METHODS: SPECT was performed with a dual-head gamma camera. Acquisition parameters were determined using a thorax phantom. Ventilation tomography after inhalation of 30 MBq (99m)Tc-diethylenetriaminepentaacetate (DTPA) aerosol was, without patient movement, followed by perfusion tomography after an intravenous injection of 100 MBq (99m)Tc-labeled macroaggregated albumin (MAA). Total SPECT acquisition time was 20 min. (99m)Tc-DTPA clearance, calculated from initial and final SPECT projections, was used for correction of the ventilation projection set before iterative reconstruction of ventilation and perfusion. The ventilation background was subtracted from the perfusion tomograms. A normalized ventilation/perfusion quotient (V/P quotient) image set was calculated. The method was evaluated on a trial group of 15 patients. RESULTS: Ventilation and perfusion images had adequate quality and showed ventilation/perfusion (V/Q quotient) relationships more clearly than did planar images. Frontal and sagittal slices were superior to planar scintigraphy for characterization of embolized areas. The V/Q quotient was supportive, particularly in the patients with chronic obstructive pulmonary disease. CONCLUSION: Fast, high-quality, ventilation/perfusion SPECT with standard isotopes doses is feasible and may contribute to higher objectivity in evaluating lung embolism as well as other lung diseases. The costs for the procedure and patient care until diagnosis are low because of the comprehensive system for the study and, particularly, the short time for its completion.

Radioisotope evaluation of the esophageal remnant and the gastric conduit after gastric pull-up esophagectomy.

BACKGROUND: The act of swallowing after gastric pull-up esophagectomy has not been thoroughly investigated. The aim of this study was to evaluate deglutition in the esophageal remnant and in the gastric conduit in patients who have undergone this operation. METHODS: The residual radionuclide activity was measured 15 seconds after a swallow in the esophageal remnant and at intervals up to a maximum of 120 minutes after a swallow in the gastric conduit. The scintigraphic rate of transit of a bolus in both areas was compared in patients who had anastomosis in the neck (n = 15) versus patients who had anastomosis in the chest (n = 19). Comparisons were also made between patients with and without symptoms of dysphagia. The scintigraphic measurements were also correlated with anastomotic diameters, measured with use of a volumetric balloon insufflation method, at 3, 6, and 12 months after operation. RESULTS: There were no significant differences in esophageal residual radionuclide activity at 15 seconds after a swallow in the groups with anastomosis in the neck versus anastomosis in the chest, with 30% residual activity up to 12 months after operation in both groups (P = .24). In the patients as a whole the 50% gastric conduit emptying time of 44 to 61 minutes did not change during the first postoperative year (P = .12). There was no association between anastomotic diameter and residual activity in the remaining esophagus (P < .126). Moderate and severe dysphagia was reported in only a few patients, and there was no correlation between dysphagic symptoms and retention in the residual esophagus or slower emptying in the gastric conduit. CONCLUSIONS: The amount of peristaltic activity in the remaining esophagus after esophagectomy with gastric replacement is unaffected by the level of the anastomosis. The gastric conduit empties slowly in all patients, and there is no correlation between the rate of emptying and either anastomotic diameter or symptoms of dysphagia.

Extravascular background subtraction using deconvolution analysis of the renogram.

The effect of the intravascular background in the renogram on the calculated renal retention function is known and can be removed. However, the effect of the extravascular background (EVB) has not been thoroughly investigated using patient data. By varying the size of the region of interest containing a single kidney and by deconvolving the 131I-hippuran and 99Tcm-DTPA renograms so generated, the following has been found: (a) the effect of EVB on the mean transit time (MTT) is negligible and EVB subtraction is not necessary, (b) the EVB overestimates the lower relative kidney function (RKF) and underestimates the higher RKF, so that EVB subtraction should be performed if the RKFs are asymmetric. A new method is described in which the correction for EVB is performed following deconvolution. If the RKFs are greater than about 30%, the correction can be performed using a regression equation between the RKFs corrected for EVB and those that are not corrected. When the RKFs are asymmetric to a greater extent, the correction should be performed for each study separately. The proposed method includes a small systematic error due to the inherent limitations of nuclear medicine equipment.

Tc-99m DMSA renal scintigraphy during kidney maturation.

A total of 282 renal scintigrams with Tc-99m DMSA in 238 children ranging in age from 10 days to 13 years performed during a 3-year period were reviewed. The authors present 94 kidneys in 85 children in whom no sign of pathology was demonstrated clinically, either by ultrasound or intravenous urography, or by micturating urethrocystography. By exploring homogeneity or heterogeneity of tracer distribution, kidney length, and background level, the authors were able to identify a "normal" pattern of tracer distribution according to age. They found that the average kidney length was 56 mm at birth, growing 1 mm per month during the first year of life, and 4 mm per year thereafter, until puberty. Average background activity was 14% of the average kidney activity at birth which decreased to approximately 6% during the first year of life, with no further decrease thereafter.

Follow-up of acute pyelonephritis in children by Tc-99m DMSA scintigraphy: quantitative and qualitative assessment.

PURPOSE: The author's goal was to create a system to identify children at risk for development of progressive renal damage. METHODS: Thirty-four children were examined with Tc-99m DMSA scintigraphy in the acute stage of an initial episode of pyelonephritis, after 6 months, and again after 1 year. The scintigraphic findings were correlated with clinical and laboratory data. RESULTS: All children had parenchymal defects in the acute stage: 93% of the kidneys and 85% bilaterally. After 6 months, the defects had diminished or disappeared in 66% of the kidneys. New defects appeared in 22%. At 1 year, no further improvement was seen in the kidneys, with an improved or unchanged pattern at 6 months. New defects appeared in 34%. Mean kidney activity uptake expressed as the percentage of administered dose (KU/AD), was low in the acute stage, increased at 6 months, with no further significant increase at 1 year. Eighty-three percent of children with urine cultures growing > or = 104 bacteria/ml at follow-up had decreased KU/AD values, whereas all children with urine cultures growing < 104 bacteria/ml had increased KU/AD values. CONCLUSIONS: Quantitative assessment increases the sensitivity of Tc-99m DMSA scintigraphy. Follow-up with this method makes it possible to identify the children with decreasing renal tubular function who may be at risk for progressive renal damage. Moderate bacteruria of 104 bacteria/ml urine is associated with deterioration of renal tubular function.

Kidney swelling. Findings on DMSA scintigraphy.

OBJECTIVE: To develop criteria identifying swollen kidneys on dimercaptosuccinic acid (DMSA) renal scintigraphy in acute pyelonephritis with regard to the DMSA distribution pattern, kidney functional size, and radioactive uptake. SUBJECTS AND METHODS: Thirty-eight children aged 15 days to 7 years with known pyelonephritis were examined with DMSA renal scintigraphy. All children were observed 2 or 3 times. In total, 94 scintigrams were evaluated. Qualitative and quantitative criteria for swelling were defined. RESULTS: Thirty-one observed kidneys satisfied the criteria of swelling. Quantitatively, kidney length and width/length were greater in swollen kidneys. Kidney uptake in percent of injected dose and kidney uptake/background were lower in swollen kidneys. Qualitatively, focal radioactive uptake defects known from a previous examination were sometimes obscured by swelling, and reappeared at follow-up. In 5 children with signs of swelling on repeat imaging, scintigraphy reinfection at the time of swelling was verified. CONCLUSIONS: Swollen kidneys may be the only sign of acute pyelonephritis on DMSA scintigraphy and swelling may obscure focal radioactive uptake defects. Measurement of kidney size and radioactive uptake can help identify swollen kidneys at DMSA scintigraphy and disclose acute pyelonephritis in the absence of overt clinical symptoms.

[Examination of gastric emptying with gamma camera. Clinically useful, uniform method now established]. / Undersökning av ventrikeltömning med gammakamera. Kliniskt användbar, enhetlig metod nu fastställd.

Although more than 30 years have passed since the introduction of scintigraphic testing of gastric emptying there has been no well-defined standard. Eight Swedish hospitals have established a nationally standardized method for scintigraphic testing of gastric emptying of solids. 160 healthy subjects participated. The meal consisted of a 99mTc-labeled omelet (1300 kJ) and 150 ml unlabeled soft drink (290 kJ). There were no differences in calculated variables between the centers. Premenopausal women showed slower emptying than postmenopausals and men of any age, making separate reference values for younger women necessary.

Regional brain perfusion changes in patients with primary generalized epilepsy assessed by Tc99m HM-PAO and SPECT.

Cerebral distribution of Tc99m-hexamethylprolenaminoxim (HMPAO) was investigated using single photon emission computerized tomography (SPECT) in 34 patients with primary generalized epilepsy (PGE) during the interictal state. These findings were compared with those in a control group of 9 healthy volunteers. In control subjects uniform selective uptake of HMPAO in cortex, basal ganglia and thalamus was found. In 30 patients (88%) decreased regional perfusion was found as follows: in the cortical region in 6 patients (18%), in the region of the basal ganglia or thalamus in 7 (20%), and in both regions in 17 patients (50%). Four patients had normal SPECT findings. The obtained results permit a hypothesis that the PGE should not be strictly differentiated from the focal epilepsy. A possible explanation of the pathophysiology of PGE has also been discussed.

Typical technetium dimercaptosuccinic acid distribution patterns in acute pyelonephritis.

Technetium dimercaptosuccinic acid renal scintiscans in 37 children with clinical diagnosis of acute pyelonephritis were reviewed. In 18 children, follow-up scintigraphy was obtained after an interval ranging from 5 to 8 months. Uptake abnormalities were found in 89% of the children (74% of the kidneys). We were able to identify four typical pathological uptake patterns: (i) pole defect(s), usually wedge shaped (60%); (ii) lateral wedge shaped defect (4%); (ii) scattered multiple defects (21%); and (iv) swollen kidney without areas of diminished uptake (15%). Remaining pathology at follow-up was found in 52% of the kidneys. Vesicoureteric reflux was present in 33% of the children with scintigraphic signs of pyelonephritis. Frequencies of parenchymal changes in the acute phase and at follow-up were not significantly correlated to the presence of reflux.

The significance of vesicoureteric reflux on kidney development assessed by dimercaptosuccinate renal scintigraphy.

OBJECTIVE: To study the influence of vesicoureteric reflux on kidney parenchyma and renal length, and identify typical distribution patterns by dimercaptosuccinate (DMSA) renal scintigraphy. PATIENTS AND METHODS: DMSA renal scintigraphies in 101 children (152 renal units) with vesicoureteric reflux grade 1-5 were reviewed. RESULTS: Three main types of pathological DMSA patterns were found: (i) dysplasia; (ii) medial defect; and (iii) pole defects. In children with no history of pyelonephritis a normal distribution pattern was found in 31%, dysplasia in 23%, medial defect in 25%, pole defects in 17% and no typical pattern in 4%. In those with a history of pyelonephritis a normal distribution pattern was found in 28%, dysplasia in 24%, medial defect in 21%, pole defects in 24% and no typical pattern in 3%. A normal pattern was significantly more frequent in kidneys with reflux grade 1-2. Dysplasia was significantly more frequent in kidneys with reflux grade 4-5. In children with no history of pyelonephritis 42% of the renal units had reduced length, 8% with no other sign of pathology. The frequency of reduced kidney length at reflux grade 1-2 did not differ significantly from that at higher grades of reflux. In children with a history of pyelonephritis 52% of the renal units had reduced length, 13% with no other sign of pathology. The frequency of reduced kidney length with a normal DMSA pattern did not differ significantly from that with a pathological pattern. CONCLUSION: The pathological DMSA distribution with vesicoureteric reflux generally conforms to one of three main patterns. Reduced kidney length is frequent even at lower grades of vesicoureteric reflux even in patients with no history of pyelonephritis, and can be the only sign of pathology.

Distribution and dosimetry of 111In DTPA-D-Phe-octreotide in man assessed by whole body scintigraphy.

The distribution and dosimetry of the somatostatin analog 111In-DTPA-octreotide was evaluated in 6 patients. Whole body scintigraphy in anterior and posterior projections was performed 0.5, 5, 24 and 48 hours after injection. Region-of-interest analysis for different organs and the whole body was used to determine 111In octreotide half-life-corrected uptake in absolute and relative terms. A rapid initial uptake was seen in the kidneys (2-7%), the spleen (2-6%) and in the liver (4-8%). A lower uptake was seen in the pituitary gland (maximum 0.3%), the thyroid (maximum 0.07%), in the female breast (maximum 1.2%), in the urinary bladder and in the intestinal tract. The elimination pattern varied between different organs. The effective dose equivalent was evaluated to be in the range 0.08 to 0.13 mSv/MBq (average 0.10 mSv/MBq). The behavior of 111In-DTPA-octreotide suggests follow-up scintigraphy in a period extending up to at least 24 hours after injection.

Kidney size estimation in piglets using dimercaptosuccinic acid (DMSA) scintigraphy.

The objective of this study was to validate kidney size measurements obtained by DMSA scintigraphy in kidneys of sizes relevant in paediatric practice. Kidney length, width and volume were measured by DMSA scintigraphy in 10 piglets in vivo and compared with measurements on excised kidneys using callipers, planar scintigraphy and submersion in water. In addition, a kidney phantom was constructed and placed in a torso phantom. The length, width and volume of the kidney phantom were compared with planar and tomographic scintigraphic measurements. The mean overestimation of kidney length by scintigraphy was 1.7% (+/- 1.2%) on excised kidneys and 3.9% (+/- 2.4%) in vivo. The corresponding figures for width measurements were 7.0% (+/- 3.9%) and 7.8% (+/- 4.4%). Tomography volume estimation overestimated the submersion volume by 23% (+/- 12%). Scintigraphic measurements on the phantom over-estimated length by 5%, width by 8% and volume by 11%. Scintigraphic renal length measurements are reliable and differ from the anatomical length by < 4% compared with excised kidneys and < 8% in vivo. Scintigraphic width measurements and volume estimations, especially on small kidneys, are less reliable.