Scintigraphy In Diagnosis Research Articles

99mTc MIBI THYMIC SCINTIGRAPHY IN DIAGNOSIS AND THERAPEUTIC DECISION MAKING: WHAT IS BEHIND THE IMAGE?

Despite CT being generally used in thymic pathology, in the case of regions with the same tissue density, only functional radioisotopic imaging can hint towards malignity. To assess the usefulness of 99mTc MIBI scintigraphy for diagnosis and treatment planning in thymoma, in relation with the radiotracer uptake mechanism. 99mTc MIBI thymic scans for 19 patients diagnosed with thymic disorders were assessed using tumor uptake ratio (UR). Specimens of thymectomies were examined and cytological assessments were correlated with the UR. The UR of all surgical patients was higher than 1.2, with a 1.5 cutoff between lymphoid hyperplasia and thymoma. The UR values were correlated with the histopathologic diagnosis (Pearson correlation 0.91, significant at p<0.01). The highest UR was 3.24, found in the case of an AB thymoma where the rate lymphocytes/epithelial cells (L/E) was 1.6. In B1 thymoma UR was 1.14 and L/E was 2.46. Phenotype differences between thymoma types correlate with 99mTc MIBI cellular uptake: lower rate L/E corresponds to higher UR, higher malignity potential and invasiveness. A thymic 99mTc MIBI UR higher than 1.5, corresponding to a CT tumoral image, is suggestive for a thymoma, requiring surgical treatment first.

DPD Scintigraphy for diagnosis of amyloidosis in 1191 patients– a single centre experience

Background 99mTechnetium labelled 3,3-diphosphono-1,2-propanodicarboxylic acid (99mTc-DPD) scintigraphy has been repurposed in recent years as a sensitive non-invasive method for imaging transthyretin (ATTR) cardiac amyloid. We have routinely performed DPD scans since June 2010 at the National Amyloidosis Centre in London, and review here our findings in a large cohort of mostly British patients.

The Utility of Hybrid SPECT/CT Lung Perfusion Scintigraphy in Pulmonary Embolism Diagnosis

Background: Pulmonary embolism (PE) is diagnosed either by ventilation/perfusion (V/Q) scintigraphy or pulmonary CT angiography. One of the imaging methods used in nuclear medicine is hybrid SPECT/CT scintigraphy. Objectives: The aim of this study was to evaluate the utility of SPECT/CT(Q) scintigraphy in the diagnosis of PE and to compare SPECT/CT(Q) with planar(Q) and SPECT(Q) methods. Methods: The study group consisted of 109 consecutive patients suspected of having PE referred for performing lung scintigraphy. The inclusion criteria were: performance of perfusion planar, SPECT and SPECT/CT scans; availability of clinical data covering a 6-month follow-up period, and D-dimer level testing. The number of eligible patients was 84. PE was reported in patients with at least 1 segmental or 2 subsegmental perfusion defects without parenchymal abnormalities on CT scans. PE was excluded when there was a normal perfusion pattern or perfusion defects were caused by lung parenchymal abnormalities or were not arranged in accordance with the pulmonary vasculature. Results: Twenty-six patients (31%) had a final diagnosis of PE. The sensitivity and specificity values of each method were as follows: planar(Q) 73 and 43%, SPECT(Q) 88 and 47% and SPECT/CT(Q) 100 and 83%. SPECT/CT(Q) yielded a significantly higher diagnostic accuracy than planar(Q) (p < 0.001) and SPECT(Q) (p < 0.001) scans. Conclusions: We conclude that hybrid SPECT/CT(Q) imaging has a high diagnostic efficacy in the diagnosis of PE. Lung perfusion scintigraphy performed with a hybrid SPECT/CT device has a significantly higher sensitivity and specificity than scanning performed with the planar or SPECT technique.

The role of bone SPECT/CT in the evaluation of painful joint prostheses.

In this study, we aimed to evaluate the contribution of single-photon emission computerized tomography/computed tomography (SPECT/CT) to three-phase planar bone scintigraphy/SPECT in the assessment of aseptic and septic prosthesis loosening in patients with painful hip and knee prostheses. Fifty patients who had undergone arthroplasties (20 hips and 30 knees) and were suspected to have complications and had undergone revision surgery were included in this study. Technetium-99m methylene diphosphonate three-phase bone scintigraphy and SPECT/CT were performed at the region of prostheses in all patients. Planar bone/SPECT and SPECT/CT images were separately assessed by two nuclear medicine physicians. SPECT/CT findings were compared with the findings of planar images/SPECT. Both planar bone scan/SPECT and SPECT/CT findings were divided into three groups: aseptic loosening, septic loosening, and miscellaneous. In all patients, scintigraphic diagnosis was confirmed by surgical findings. SPECT/CT changed the diagnosis and treatment plan in 8/50 (16%) patients. SPECT/CT was significantly better than planar scan/SPECT imaging for the diagnosis of aseptic and septic loosening in both joints (κ value: 0.477 for planar scan/SPECT; κ value: 0.717 for SPECT/CT). Moreover, both planar scan/SPECT and SPECT/CT were statistically successful in knee prostheses than in hip prostheses (κ value: 0.271 vs. 0.579 for planar/SPECT; κ value: 0.579 vs. 0.80 for SPECT/CT). For the hip, SPECT/CT was successful on the acetabular component than on the femoral component. For the knee, the results of SPECT/CT were similar for the femoral and tibial components. SPECT/CT increases diagnostic accuracy in the evaluation of aseptic and septic loosening in hip and knee prostheses compared with three-phase bone scintigraphy/SPECT.

99m-Tc-ubiquicidin scintigraphy in diagnosis of knee prosthesis infection and comparison with F-18 fluorodeoxy-glucose positron emission tomography/computed tomography

Total knee arthroplasty has witnessed a significant increase in recent years. Despite the advantages of this surgical procedure, it has some complications, the most serious of which is prosthetic infection. The discrimination of bacterial infections from sterile inflammatory processes is of great importance in the management of periprosthetic infection (PPI). Ubiquicidin (UBI) is a synthetic antimicrobial peptide fragment reported to be highly infection-specific. Tc99m-UBI has recently been reported to be a promising radiotracer for infection imaging. We report a case of left knee PPI diagnosed using 99mTc-UBI scintigraphy and compared with F-18 fluorodeoxy-glucose positron emission tomography.

Enostosis-like lesions in equids: 79 cases (1997-2009).

To evaluate equids with enostosis-like lesions (ELLs) and document the clinical and epidemiological features of this disease. Retrospective case series. 79 equids with a scintigraphic diagnosis of at least 1 ELL on ≥ 1 occasion. Medical records of 4,992 equids that underwent bone scintigraphy between March 1997 and March 2009 were reviewed; 78 horses and 1 pony had a scintigraphic diagnosis of an ELL. For those equids, signalment; physical, scintigraphic, radiographic, and lameness examination results; and outcome were reviewed. Of the 79 equids, 4 (5.1%) had anatomically distinct ELLs on 2 (n = 3) or 4 (1) separate occasions that caused lameness in different limbs. Thus, there were 85 ELL-related admissions to the hospital. Overall, 157 ELLs were detected. Among all equids undergoing scintigraphic examination, Thoroughbreds were more commonly and Standardbreds were less commonly affected. Older animals were more likely to have ELLs. Lameness was directly attributed to scintigraphically evident ELLs in 42 of the 85 (49.4%) admissions. The tibia (62/157 [39.5%]) and the radius (46/157 [29.3%]) were most commonly affected. The ELLs located in the humerus caused more severe lameness than did ELLs in other anatomic locations. Lameness severity was associated with radiopharmaceutical uptake intensity. Among racehorses, those with 1 ELL were more likely to return to racing than were those with multiple ELLs detected in 1 scintigraphic examination; mean interval from diagnosis to first start was 184 days. Results of this retrospective evaluation of a large group of equids with ELLs have provided a better understanding of this disease process.

Lung scintigraphy in the diagnosis of pulmonary embolism: pathophysiological and practical evidence

The protean clinical presentation of pulmonary embolism (PE) is the consequence of a complex series of haemodynamic and respiratory changes caused by the impact of thrombi within the pulmonary vasculature. Haemodynamic changes result from obstruction of the pulmonary arterial bed leading to increased pulmonary vascular resistances and they are manifested clinically as dyspnoea, engorgement of neck veins, and systemic arterial hypotension. Respiratory changes are characterised by lung volume reduction, hypocapnia and hypoxaemia. Reduced lung volume is mainly due to pulmonary consolidation, atelectasis and decreased distension of the thoracic cage due to chest pain. These pathophysiological changes affect both perfusion and ventilation and could explain the low sensitivity of the ventilation/perfusion (V/Q) mismatch scintigraphic approach in diagnosing PE. Acute PE causes redistribution of pulmonary blood flow from non-perfused areas and, to a lesser extent, of ventilation; this is a further factor arguing against the use of V/Q mismatch for the scintigraphic diagnosis of the disease. Hypoxaemia is primarily the consequence of V/Q abnormalities, namely the development of areas with a low V/Q ratio. On a Q scan this can easily be appreciated from hyperperfused lung areas that, by themselves, are a marker for the scintigraphic diagnosis of PE. In conclusion, a Q scan without a V scan, when properly interpreted according to the prospective investigative study of acute pulmonary embolism diagnosis methodology (presence or absence of wedge-shaped perfusion defects) and combined with the formulation of a pre-test clinical probability, can be used in most patients with clinical suspicion of PE, reducing costs and radiation load, increasing the practicality of the examination, and providing diagnostic accuracy comparable to that of CT angiography.

Surgical Treatment of Hemimandibular Hyperplasia Leading to Unilateral Overdevelopment of the Face

Introduction:: Hemimandibular hyperplasia is a facial deformity which may develop in any age and includes a unilateral enlarged mandibular condylar head, deviation of mandible and chins, elongated condylar neck or ramus, and an occlusal cant with open bite. Different surgical treatments are proposed in the literature from simple low or high condylectomy to more complex procedures combining osteotomies in different sites of the mandible. Surgical procedure is defined by the clinical evaluation and scintigraphic diagnosis of activity or inactivity in the center of condylar growth. Case Presentation:: This case report describes a 30-year-old female patient with left hemimandibular hyperplasia with activity of condylar growth, that was successfully treated with low condylectomy, asymmetric lefort I osteotomy and inferior border ostectomy on the affected side, and associated with a unilateral sagittal split ramus osteotomy on the contra-lateral side. Discussion:: The innovation on nerve dissection by removing the overlying buccal bone and performing inferior ostectomy under direct visualization of the nerve, proved to be a safe technique with a low risk of nerve damage.

Radiosynthesis of [124I]Iodometomidate and Biological Evaluation Using Small-Animal PET

The application of radiolabelled inhibitors of cytochrome P450 enzymes is a novel approach for molecular imaging of adrenocortical masses to detect adrenal tumours. One potential tracer is radiolabelled iodometomidate (IMTO) with a common option for scintigraphic diagnosis and therapeutic applications. The aim of this study was to radiolabel iodometomidate with the positron-emitting radionuclide iodine-124 ((124)I) for the investigation of the biological behaviour and pharmacokinetics with positron emission tomography (PET). [(124)I]IMTO has been synthesized by oxidative radioiodo-destannylation, purified via semi-preparative HPLC and formulated in acetate-buffered saline, which contained ascorbic acid and ethanol to avoid radiolytic decomposition. Biological evaluation was performed in rats which received 5.5 ± 0.7 MBq [(124)I]IMTO in vivo. The radioactivity distribution (n = 3) has been dynamically imaged from 0-120 min after intravenous (i.v.) injection by small-animal PET. Regions of interest have been defined manually in the reconstructed PET images, and the activity concentration was expressed as percent injected dose per gram tissue (%ID/g). [(124)I]IMTO was prepared with a radiochemical yield of 83 ± 5 % (n = 3) and a radiochemical purity of >97 %. The final formulation of [(124)I]IMTO was stable for up to 48 h at room temperature. Two hours after i.v. administration in rats, radioactivity concentration in the adrenal glands were 2.1 ± 0.3 %ID/g, which was sufficient to achieve highest-contrast adrenal PET images. In the present study, the biological characteristics of radioiodinated metomidate were evaluated. [(124)I]IMTO appears as an attractive PET tracer for imaging of adrenals.

Captopril Renal Scintigraphy in Screening and Diagnosis of Renal Artery Stenosis - A Prospective Study

The present study was carried out to assess the role of Tc99m-DTPA captopril renal scintigraphy in screening and diagnosing of patients with renal artery stenosis. Materials and Methods: A total of 26 hypertensive patients with a clinical suspicion of RAS underwent baseline and captopril scintigraphy using 259-370 MBq (7-10mCi) of Tc99m-DTPA. The captopril scintigraphy was done after oral dose of 50mg of captopril with in three baseline study. DSA was done in all patients irrespective of scintigraphy results due to high clinical suspicion of RAS. Results: Of 26 patients, 18 had renal artery stenosis (10 unilateral, 8 bilateral), making a total of 26 involved RA on DSA. Of these 26 involved RA, 16 were stenosis&gt; 60%, 2 were stenosed&lt; 60% while 8 were completely occluded. Of the sixteen RA with stenosis &gt; 60%, only 12 were detected by captopril scintigraphy (Sensitivity-75%). Eight kidneys with complete occlusion, 6 were non-functioning and 2 were poorly functioning (&lt;20%) on scintigraphy. Among 27 normal RA, (25 normal and two &lt;60% stenosis) only 19 were negative on scintigraphy (specificity-70%). Two kidneys with less than 60% stenosis were positive on scintigraphy. The overall accuracy of captopril DTPA scintiography was found to be 72.1% with PPV and NVP of 66.7% and 82.6% respectively. Two patients with accessory RA were not picked up on captopril scintigraphy. Conclusion: Tc99m-DTPA captopril scintigraphy has average sensitivity and specificity. The effectiveness of captopril scintigraphy in diagnosis of completely occuluded RA, accessory RAS and RAS in poorly functioning kidney is poor, therefore this test cannot be considered as screening test for RVH. Nepalese Journal of Radiology; Vol. 2; Issue 2; July-Dec. 2012; 28-35 DOI: http://dx.doi.org/10.3126/njr.v2i2.7682

99mTc-Szintigraphie versus Farbduplex-Sonographie

SummarySince the development of colour coded duplex-sonography (ccds), several attempts have been made to implement this technique for diagnosis of focal lesions in the thyroid. There are controversial discussions on whether ccds might replace thyroid scintigraphy in diagnosis of hyperfunctional thyroid nodules. Aim of this study was the comparison of ccds and thyroid scintigraphy in diagnosis of functional thyroid autonomy. Patients, material and methods: 192 patients with thyroid nodules &gt; 10mm detected by conventional sonography underwent thyroid scintigraphy. Additionally, these patients were subjected to ccds of the thyroid. In total, 286 thyroid nodules were examined by scintigraphy, ccds and blood tests. Results: Thyroid scintigraphy showed 67% of thyroid nodules as hyperfunctional, 19% indifferent and 14% as hypofunctional. Mean 99mTc uptake of hyperfunctional nodules was 2.19%, of indifferent nodules 1.12% and of hypofunctional nodules 1.06% respectively. The ccds allowed perinodular measurement of flow speed (hyperfunctional: 0.23 ± O.1 m/s; hypofunctional: 0.22 ± 0.1; indifferent: 0.21 ± 0.09), resistance index (hyperfunctional: 1.21 ± 1.16; hypofunctional: 0.62 ± 0.48; indifferent: 0.93 ± 1.02) and pulsatility index (hyperfunctional: 0.97 ± 0.45; hypofunctional: 0.84 ± 0.4; indifferent: 1.04 ± 0.6) in all nodules as well as intranodular measurement in some of the nodules (24% in hyperfunctional, 2% in indifferent and 15% in hypofunctional nodules). Statistic analysis of the obtained ccds data did not show any practically relevant correlations (p&gt;0.05) with 99mTc uptake, basal TSH, fT3 or fT4. Conclusion: Thyroid scintigraphy cannot be replaced by ccds for diagnosis of functional thyroid autonomy. Reliable diagnostics still require a combination of thyroid scintigraphy, sonography and blood tests.

Value of 99Tcm-MDP SPECT bone scintigraphy in diagnosis of unilateral condylar hyperplasia of the mandible

Objective To investigate the clinical value of 99Tcm-MDP SPECT scintigraphy in diagnosis of unilateral condylar hyperplasia (UCH) of the mandible.Methods Temporomandibular joint tomography using 99Tcm-MDP SPECT was performed in 56 UCH patients (22 males,34 females,mean age 21.5 y) preoperatively and 10 controls with other diseases (5 males,5 females,mean age 22.6 y).Thirtyone UCH patients received high condylar resection,and the corresponding histopathological results were analyzed.All scintigrams were visually interpreted and supported by semi-quantitative assessment of activity in bilateral using the skull as the reference site.The results of UCH patient and control groups were compared using two-sample and paired t tests.Pearson correlation analysis was also used.Results Affected condyle/parietal bone and affected condyle/bilateral condyles activity ratios (1.66 ±0.63 and 0.59 ±0.44) were significantly higher than those of the contralateral side (1.34 ±0.34 and 0.41 ±0.04 ; t =3.687 and 6.590,respectively,both P ＜ 0.01) and controls (1.12 ± 0.07 and 0.50 ± 0.01,t =6.459 and 4.750,respectively,both P ＜ 0.001).The sensitivity,specificity,positive and negative predictive values for the diagnosis of condylar hyperplasia were 95.2％ (20/21),60.0％ (6/10),83.3％ (20/24),and 6/7.The uptake on scintigraphy was not significantly related to the thickness of the cartilage (respective mean thicknesses of fibrous,proliferative,hypertrophic cartilage layers:(150.5 ± 94.9),(185.2 ±113.6),(167.7±76.9) μm,r=0.46,0.47,-0.12,all P＞0.05).Conclusion 99Tcm-MDPSPECT scintigraphy may be useful for assessment of growth activity of the mandibular condyle and to provide important information for condylar hyperplasia in surgical planning. Key words: Temporomandibular joint diseases; Mandibular condyle; Radionuclide imaging; MDP

Should HIV-infected patients be screened for silent myocardial ischaemia using gated myocardial perfusion SPECT?

A higher prevalence of cardiovascular risk factors (CRFs) in HIV-infected patients, together with chronic infection and treatments, has resulted in an increased risk of silent myocardial ischaemia (SMI). The objective of this study was to evaluate whether myocardial SPECT should be used for screening HIV-infected patients with no clinical symptoms of coronary artery disease. The prevalence of SMI detected by myocardial SPECT was determined in 94 HIV-infected patients with a normal clinical cardiovascular examination in relation to anthropomorphic parameters, CRFs, inflammatory and HIV infection status, and treatment. Coronary artery disease was detected in nine patients (eight with ischaemia, one with myocardial infarction), corresponding to 9.6 % positivity. All but two of the scintigraphic diagnoses of ischaemia were confirmed by coronarography. Univariate analysis revealed that the overall number of CRFs and the combination of gender and age were associated with a diagnosis of SMI (p < 0.05). According to multivariate analysis, the only independent parameter significantly associated with the scintigraphic diagnosis of SMI was the combination of gender and age (p = 0.01). All the positive myocardial SPECT scans were in men older than 52 years with at least two other CRFs. In this subpopulation of 47 patients, the prevalence of SMI detected by myocardial SPECT reached 19.2 %. In male HIV-infected patients older than 52 years and with at least two other CRFs, screening for SMI using myocardial SPECT was about four times more likely to be positive than in the general population. This may motivate physicians to advise these patients to undergo more systematic screening for SMI using this technique.

Correction of Facial Asymmetry Resulting From Hemimandibular Hyperplasia

Hemimandibular hyperplasia is a facial deformity in which there is an increase in the condyle, neck of the condyle or ramus, and an occlusal cant. Different surgical treatments are proposed in the literature, from simple low or high condylectomy to more complex procedures combining osteotomies in different sites of the mandible. Surgical procedure is defined by the scintigraphic diagnosis of activity or inactivity in the center of condylar growth. The case report describes a 35-year-old female patient with hemimandibular hyperplasia on the left side with inactivity of condylar growth, successfully treated with bilateral sagittal split ramus osteotomy associated with a basilar osteotomy in form of "L" on the affected side. The surgical technique was easily executed, with an improvement in function, aesthetics, and patient satisfaction. Correction of facial asymmetry caused by excessive growth of the mandible using this basilar osteotomy in the form of "L" combined with bilateral sagittal split ramus osteotomy proved to be a relatively simple technique of easy execution with a low risk of nerve damage.

Renal scintigraphy in diagnosis and management of nephroptosis

Clinical manifestations of Nephroptosis are ubiquitous. Diagnosis is achieved after ruling out all other causes of abdominal pain by investigations. However, Nuclear Scan with Tc-99m GHA, MAG 3 and DTPA renal agents with dedicated imaging in supine and erect postures confirms the diagnosis5. Not only as a diagnostic aid, it also helps in decision making for surgical correction by depicting the changes in drainage and GFR in different postures. We describe a case of Nephroptosis where DTPA Renal Scintigraphy addressed the diagnostic and therapeutic issues in the case.

Diagnosis of bone infection by complementary role of technetium-99m MDP and technetium-99m hexamethylpropylene-amineoxime-leukocytes

Purpose:Valuate complementary role of 99mTc-MDP bone scan and 99mTechnetium hexamethylpropylene-amineoxime (99mTc-HMPAO) labeled leukocyte scintigraphy in diagnosis of bone infection.Patients and Methods:Ninety one sites suspected to have bone infection were divided in to two groups: Group I 49 sites with current endo-prothesis; and group II 42 sites with no prosthesis. All patients were subjected to serial images of 99mTc-HMPAO labeled leukocyte (99mTc-white blood cells (WBCs)), triple phase bone scan (99mTc-MDP) and plain X-ray, in addition to clinical and bacteriological assessment, together with follow-up.Results:The overall sensitivity (Sn) was found to be 34.9%, 95.4%, and 86% for plain X-ray, 99mTc-MDP, and 99mTc-WBCs respectively. Concerning specificity (Sp) was found to be 47.9%, 45.8%, and 91.7% respectively for the three imaging modalities. 99mTc-WBCs showed better Sn, Sp, and accuracy in group I (95%, 93.1% and 93.9%, respectively) compared to 40%, 41.4%, and 40.8% for plain X-ray and 90%, 62%, and 73.5% respectively for 99mTc-MDP. On the other hand, 99mTc-MDP proved to have best Sn 100% versus 78.3% and 30.4% for 99mTc-WBCs and plain X-ray respectively. Yet, Sp and accuracy was found to best for 99mTc-WBCs (89.5% and 83.3% respectively) compared to 57.9% and 42.9% for plain X-ray and 21.1% and 64.3% for 99mTc-MDP.Conclusion:Combined imaging with 99mTc-WBCs and 99mTc-MDP proved to be effective in early detection of bone infection in the presence or absence of prosthesis.

The Diagnostic Value of 99mTc-IgG Scintigraphy in the Diabetic Foot and Comparison with 99mTc-MDP Scintigraphy

Diabetic foot infection is the most common etiology of nontraumatic amputation of the lower extremities, and early diagnosis is of great importance in its management. The aim of this prospective study was to evaluate the strength of (99m)Tc-IgG scintigraphy in diagnosis of osteomyelitis of the diabetic foot and to compare (99m)Tc-IgG scintigraphy with (99m)Tc-methylene diphosphonate (MDP) scintigraphy. A prospective university hospital-based study was performed over 24 mo. Eighteen patients with type II diabetes and foot ulcers (15 men and 3 women; age range, 45-80 y) were referred for imaging because of clinically suspected osteomyelitis. Early (5-h) and late (24-h) (99m)Tc-IgG scanning and 3-phase skeletal scintigraphy were completed for all patients at a 3- to 4-d interval. Regions of interest over the involved bony sites and the contralateral normal sites were drawn, and the abnormal-to-normal ratios were acquired for both (99m)Tc-IgG and (99m)Tc-MDP studies. From a total of 23 lesions, we observed 10 sites of osteomyelitis, 10 sites of cellulitis, and 3 sites of aseptic inflammation confirmed by MRI, clinical presentation, histopathologic examination, and follow-up evaluation as a gold standard. Both (99m)Tc-IgG and (99m)Tc-MDP scanning showed excellent sensitivity for diagnosis of osteomyelitis, but the specificity was significantly lower (69.2% and 53.8%, respectively). Sensitivity, specificity, and accuracy in the diagnosis of osteomyelitis were, respectively, 100%, 53.8%, 73.9% for (99m)Tc-MDP scanning; 100%, 69.2%, 82.6% for 5-h (99m)Tc-IgG scanning; and 60%, 76.9%, 69.5% for 24-h (99m)Tc-IgG scanning. There was no significant difference between the semiquantitative indices of 5-h and 24-h (99m)Tc-IgG scanning for inflammation, cellulitis, and osteomyelitis. Although both (99m)Tc-IgG and (99m)Tc-MDP scintigraphy have high sensitivity for the diagnosis of osteomyelitis, the specificity of these studies is poor. For (99m)Tc-IgG scintigraphy, 5-h images appear to be adequate, and there is little benefit to performing additional imaging at 24 h.

Role of 99mTc-DPD Scintigraphy in Diagnosis and Prognosis of Hereditary Transthyretin-Related Cardiac Amyloidosis

In a cohort of patients with hereditary transthyretin-related amyloidosis (ATTR), we aimed to assess the role of (99m)Tc-3,3-diphosphono-1,2-propanodicarboxylic acid ((99m)Tc-DPD) in detecting myocardial amyloid infiltration across a wide spectrum of cardiac involvement and in predicting major adverse cardiac events (MACE). Hereditary transthyretin-related amyloidosis is a challenging and underdiagnosed condition where both early diagnosis and prognosis remain problematic. We evaluated 63 patients with ATTR: 40 with and 23 without echocardiographically diagnosed amyloidotic cardiomyopathy (AC). Myocardial uptake of (99m)Tc-DPD scintigraphy was semiquantitatively and visually assessed at 5 min and 3 h. All patients with AC showed moderate-to-severe myocardial tracer uptake (i.e., visual score ≥2). Within the subgroup without AC, only 4 patients (with Ala36Pro, Gly47Ala, Thr49Ala, and Glu89Gln transthyretin mutations) showed myocardial tracer uptake and abnormal heart/whole body retention (H/WB) values: in all these cases endomyocardial biopsies showed amyloidotic infiltration. The H/WB was positively correlated with left ventricular (LV) mean wall thickness (Pearson's r=0.695, p<0.001) and negatively with LV ejection fraction (r=-0.368, p=0.004). The H/WB was an unfavorable predictor of MACE-free survival at Cox univariate analysis and contributed to the multivariate model. Notably, LV wall thickness >12 mm in combination with H/WB >7.5 was associated with the highest event rate. In ATTR, (99m)Tc-DPD scintigraphy can identify myocardial infiltration across a wide spectrum of morphologic/functional cardiac involvement, allowing an early diagnosis of the disease (even before the appearance of echocardiographic abnormalities). The (99m)Tc-DPD myocardial uptake is a prognostic determinant of "cardiac" outcome in ATTR, either alone or in combination with LV wall thickness.

Current Role of 111In-DTPA-Octreotide Scintigraphy in Diagnosis of Thymic Masses

Thymic tumors (thymomas and thymic carcinomas) represent 50% of all mediastinal tumors. Thymomas usually express high levels of somatostatin receptors, which enable in vivo imaging with 111In-DTPA-octreotide (OctreoScan®). The aim of this study was to further investigate the role of radionuclide techniques in the diagnosis, staging and follow-up of these tumors. Eight patients (5 women, 3 men, age range 35-79 years; mean ± SD 56.1 ± 15.8 years) entered the study. In 4 patients, myasthenia gravis was the presenting symptom. 111In-DTPA-octreotide scan was performed within 3 weeks after contrast enhanced CT and/or MRI. Planar and tomographic images were acquired within 24 hours of the injection of 111 MBq OctreoScan. The scintigraphic results were defined in correlation with the histological findings. Histology revealed thymoma in 3 patients, thymic carcinoma in 1, insular carcinoma of presumably thymic origin in 1, thymic carcinoid in 1, and thymic hyperplasia in 2 patients. Two thymomas were at stage I, 1 thymoma and 1 thymic carcinoma at stage II, 1 insular carcinoma of presumably thymic origin at stage IV, and 1 thymic carcinoid at stage IV. OctreoScan consistently accumulated in primary and/or metastatic sites of thymic tumors while no radiotracer uptake was detected in the 2 patients with benign thymic hyperplasia. In 1 patient with a very large mediastinal mass (13 cm in largest diameter) and multiple metastatic deposits in the lungs, OctreoScan scintigraphy showed a large area of pathological uptake in the anterior mediastinum and a small area of focal uptake in the cervical-dorsal region of the right lung corresponding to a lymph node expressing somatostatin receptors. OctreoScan is avidly taken up by thymic tumors, enabling the diagnosis of these tumors and a better evaluation of their extension. It does not accumulate in thymic hyperplasia, thus allowing the differential diagnosis between these 2 pathological conditions. In patients affected by myasthenia gravis, OctreoScan scintigraphy can play an important role in characterizing thymic masses.

Controversies in Diagnosis of Pulmonary Embolism

The approach to the diagnosis of acute pulmonary embolism (PE) is under constant revision with advances in technology, noninvasive approaches, and increasing awareness of the risks of ionizing radiation. Optimal approaches in some categories of patients are controversial. Data are insufficient for evidence-based recommendations. Therefore, this survey of investigators in the field was undertaken. Even among experts there were marked differences of opinion regarding the approach to the diagnosis of acute PE. Although CT pulmonary angiography was usually the imaging test of choice, the respondents were keenly aware of the dangers of ionizing radiation. In view of advances in scintigraphic diagnosis since the Prospective Investigation of Pulmonary Embolism Diagnosis (PIOPED) trial, ventilation/perfusion (V/Q) lung scans or perfusion scans alone and single photon emission computed tomography (SPECT) V/Q lung scans are often recommended. The choice depends on the patient's age, gender, and complexity of the findings on the plain chest radiograph.