SPECT and PET serve as molecular imaging techniques and in vivo biomarkers for brain metastases

Nuclear medicine techniques (single photon emission computerized tomography, SPECT, and positron emission tomography, PET) represent molecular imaging tools, able to provide in vivo biomarkers of different diseases. To investigate brain tumours and metastases many different radiopharmaceuticals imaged by SPECT and PET can be used. In this review the main and most promising radiopharmaceuticals available to detect brain metastases are reported. Furthermore the diagnostic contribution of the combination of SPECT and PET data with radiological findings (magnetic resonance imaging, MRI) is discussed

La Medicina Nucleare nella diagnostica delle demenze

La Medicina Nucleare si differenzia dalle altre metodiche di neuroimaging per la capacità di visualizzare nel vivente anomalie funzionali e biomolecolari con elevati valori si sensibilità e specificità. Le due tecniche PET (tomografia ad Emissione di Positroni) e SPECT (tomografia ad emissione di fotone singolo), un numero elevato di radiofarmaci ed una avanzata tecnologia hardware e software giustificano l’interesse dei clinici verso questa giovane disciplina medica soprattutto in un ambito complesso quale quello della diagnosi delle demenze. L’uso della medicina nucleare nella diagnostica delle demenze infatti è supportato oltre che dai dati di Letteratura anche dalle indicazioni fornite da diverse recenti linee guida pubblicate in campo nazionale ed internazionale. Nuclear Medicine differs from other neuroimaging methods for the ability to visualize in living subjects functional and biomolecolar abnormalities with high sensitivity and specificity. The two different techniques PET e SPECT, the large number of radiofarmaceutical and the advanced hardware and software technology have stimulated the interest of clinicians to this recent branch of medicine. The use of Nuclear Medicine in dementia diagnosis is in fact well supported by a large number of literature data also from the information provided by the recent national and international guidelines

¹³¹I SPECT/CT in the follow-up of differentiated thyroid carcinoma: incremental value versus planar imaging

Planar 131I scintigraphy is routinely used to detect radioiodine-avid metastases of differentiated thyroid carcinoma (DTC). However, the modality has limitations, such as low sensitivity and lack of anatomic landmarks. We investigated whether SPECT with integrated low-dose CT may have additional value over planar imaging in detecting residue and metastases in DTC patients. Methods: We studied 117 consecutive thyroidectomized DTC patients. On 2 different hybrid dual-head γ-cameras (55 patients on one camera and 62 on the other), 108 patients underwent 131I diagnostic imaging and SPECT/CT, and 9 underwent posttherapeutic 131I planar imaging and SPECT/CT. We assigned an incremental value to SPECT/CT when it provided better identification and interpretation of the foci of radioiodine uptake, more correct anatomic localization and characterization, and precise differentiation between tumor lesions and physiologic uptake. Results: Planar imaging showed 116 foci of uptake in 52 of 117 patients, and SPECT/CT showed 158 foci in 59 of 117 patients, confirming all foci seen on planar imaging but identifying an additional 28 occult foci in 10 of 52 patients. Fourteen occult foci were shown on SPECT/CT in 7 further patients whose planar imaging findings were negative. SPECT/CT correctly characterized 48 foci unclear on planar imaging, also defining location and extent. SPECT/CT was a determinant in classifying as neoplastic those foci for which planar imaging seemed to exclude malignancy, discriminating between residue and lymph node metastases in the neck, some of which were adjacent to salivary glands and had been missed on planar imaging. SPECT/CT also showed occult lesions in the mediastinum, abdomen, and pelvis and identified small bone metastases unsuspected on planar imaging. Globally, SPECT/CT had an incremental value over planar imaging in 67.8% of patients, modified therapeutic management in 35.6% of positive cases, and avoided unnecessary treatment in 20.3% of patients with only single benign lesions or physiologic uptake. Conclusion: 131I SPECT/CT improved planar data interpretation, showing a higher number of DTC lesions, more precisely localizing and characterizing DTC foci, and more correctly differentiating between physiologic uptake and metastases, thus permitting the most appropriate therapeutic approach to be chosen. A wider use of this method is suggested complementary to planar imaging in selected DTC patients

Scintimammography with a high resolution dedicated breast camera in comparison with SPECT/CT in primary breast cancer detection

AIM: We evaluated the usefulness of planar scintimammography (SM) with a high resolution dedicated breast camera (DBC) in comparison with single photon emission computed tomography (SPECT)/computed tomography (CT) in primary breast cancer detection. METHODS: A consecutive series of 157 patients with breast lesions suspicious for cancer at conventional diagnostic procedures were studied with both DBC planar SM and SPECT/CT using [(99M)Tc]tetrofosmin as radiotracer. Scintigraphic data have been related with definitive histopathological findings in all cases. RESULTS: Breast cancer was ascertained in 127/157 patients and benign disease in the remaining 30 cases, with a total of 140 carcinomas and 33 benign lesions. DBC planar SM detected 95.7% of overall carcinomas, while SPECT/CT 90.7% (P<0.01). In =/<10 mm carcinomas, sensitivity was 89.1% for DBC planar SM and 78.3% for SPECT/CT (P<0.05); in carcinomas>10 mm the corresponding values were 98.9% and 96.8%, respectively. Specificity value was 87.9% for both procedures; accuracy value was 94.2% for DBC and 90.2% for SPECT/CT (P<0.01). Forty-six out of 127 breast cancer patients had axillary lymph node metastases; SPECT/CT was positive in 36/46 (78.3%) cases and showed a 96.4% specificity value. DBC planar SM identified metastases in only 4 cases. CONCLUSION: DBC planar SM proved a useful diagnostic method in primary breast cancer detection, showing significantly higher sensitivity and accuracy values than SPECT/CT, especially in small size carcinomas. Thus, DBC planar SM should be preferred, although SPECT/CT, given its high performance, could represent a useful alternative when DBC is not available. Moreover, SPECT/CT, but not DBC, can contribute to providing information on axillary lymph node status

The Clinical impact of breast scintigraphy acquired with a breast specific γ-camera (BSGC) in the diagnosis of breast cancer: incremental value <i>versus</i> mammography

We investigated the clinical impact of breast scintigraphy acquired with a breast specific γ-camera (BSGC) in the diagnosis of breast cancer (BC) and assessed its incremental value over mammography (Mx). A consecutive series of 467 patients underwent BSGC scintigraphy for different indications: suspicious lesions on physical examination and/or on US/MRI negative at Mx (BI-RADS 1 or 3), characterization of lesions suspicious at Mx (BI-RADS 4), preoperative staging in lesions highly suggestive of malignancy at Mx (BI-RADS 5). Definitive histopathological findings were obtained in all cases after scintigraphy: 420/467 patients had BC, while 47/467 patients had benign lesions. The scintigraphic data were correlated to Mx BI-RADS category findings and to histology. The incremental value of scintigraphy over Mx was calculated. Scintigraphy was true-positive in 97.1% BC patients, detecting 96.2% of overall tumor foci, including 91.5% of carcinomas ≤10 mm, and it was true-negative in 85.1% of patients with benign lesions. Scintigraphy gave an additional value over Mx in 141/467 cases (30.2%). In particular, scintigraphy ascertained BC missed at Mx in 31 patients with BI-RADS 1 or 3, including 26 patients with heterogeneously/high dense breast (19/26 with tumors ≤10 mm) and detected additional clinically occult ipsilateral or controlateral tumor foci (all &lt;10 mm) or the in situ component sited around invasive tumors in 77 BC patients with BI-RADS 4 or 5, changing surgical management in 18.2% of these cases; moreover, scintigraphy ruled out malignancy in 33 patients with BI-RADS 4. BSGC scintigraphy proved a highly sensitive diagnostic tool, even in small size carcinoma detection, while maintaining a high specificity. The procedure increased both the sensitivity of Mx, especially in dense breast and in multifocal/multicentric disease, and the specificity as well as it better defined local tumor extension, thus guiding the surgeon to a more appropriate surgical treatment

The Role of planar scintimammography with high-resolution dedicated breast camera in the diagnosis of primary breast cancer

Planar scintimammography (SM) acquired with a conventional γ camera has proved a useful complementary tool to mammography (Mx) in breast cancer (BC) diagnosis, but with unsatisfactory sensitivity in small size carcinomas. In this study we assessed the role of planar SM with a high-resolution dedicated breast camera (DBC) in BC diagnosis, comparing the results with those of Mx. A consecutive series of 145 patients scheduled for biopsy for suspected BC underwent Tc-99m tetrofosmin planar SM using a newly developed DBC. Scintigraphic data were compared with Mx findings and correlated to histology. Histopathologic analysis revealed 165 lesions: 143 malignant and 22 benign. SM detected 139/143 carcinomas (overall sensitivity: 97.2%) and was true negative in 19/22 benign lesions (overall specificity: 86.4%). SM sensitivity was 91% in ≤=10-mm carcinomas. SM was more accurate than Mx in 42/145 cases (29%), detecting cancer in 9 patients with Mx indeterminate for dense breasts (8/9 tumors were &lt;10 mm), assessing additional tumor foci (all &lt;10 mm) in 5 points with multifocal disease and correctly classifying 28 patients with inconclusive mammographic findings as affected by cancer or by benign disease. Mx was more accurate than SM in 3 patients, in each detecting 1 subcentimeter BC false negative on SM. DBC planar SM seems a highly sensitive diagnostic tool in the detection of BC, even when small in size, and in the assessment of multifocal disease. A wider employment of this procedure is thus suggested, especially in indeterminate or inconclusive mammographic findings to improve sensitivity and specificity of Mx

Scintimammography with high resolution dedicated breast camera and mammography in multifocal, multicentric and bilateral breast cancer detection: a comparative study

AIM: The aim of this study was to compare preoperative planar scintimammography (SM) with high resolution dedicated breast camera (DBC) and conventional mammography in the detection of multifocal, multicentric and bilateral breast cancer and its impact on surgical planning. METHODS: A series of 264 consecutive patients, 232 with breast cancer and 32 with benign lesions, underwent [(99m)Tc]tetrofosmin planar SM with a newly developed DBC (LumaGEM 3200S/12K, Gamma Medica-Ideas Inc.). Scintigraphic with mammography data were compared and correlated with histopathological findings. RESULTS: At surgery, ipsilateral multifocal or multicentric breast cancer in 40 patients, invasive in 24 cases (group 1) and in situ in 16 (group 2) was ascertained, and synchronous bilateral breast cancer in 4 patients (group 3). Globally, SM was positive for cancer in 41 out of the 44 breast cancer patients (93.2%) and mammography was positive in 40 out of 44 (90.1%). SM revealed multifocal/multicentric disease in 87.5% of group 1/goup 2 patients and mammography in 47.5% (P&lt;0.0005): SM detected a significantly higher number of additional invasive foci than mammography (89.6% vs 37.9%, P&lt;0.0005); only SM revealed ipsilateral multifocality/multicentricity in 35% of cases. Bilaterality was detected by SM in 100% of group 3 patients and by mammography in 75%. Overall specificity was 88.2% for SM and 52.9% for mammography. SM correctly changed surgical management in 16% of cases. CONCLUSION: DBC planar SM proved a more highly sensitive diagnostic method than mammography in the preoperative assessment of both ipsilateral multifocal/multicentric breast cancer and synchronous bilateral breast cancer. The procedure contributed to correctly changing patient surgical management in some cases, suggesting its wider use complementary to mammography

The Role of (99m)Tc-tetrofosmin pinhole-SPECT in breast cancer non palpable axillary lymph node metastases detection

AIM: We evaluated the usefulness of (99m)Tc-tetrofosmin axillary pinhole (P)-SPECT in breast cancer (BC) non palpable axillary lymph node metastasis detection compared with conventional planar and SPECT scintimammography. METHODS: We studied prospectively 188 consecutive patients with suspected primary BC, negative at axillary clinical examination. Ten minutes after 740 MBq (99m)Tc-tetrofosmin injection, planar and SPECT scintimammography were acquired, followed by axillary P-SPECT imaging. RESULTS: At histology, 12 patients had benign mammary lesions and 176 had BC. Axillary lymph node dissection (ALND) was performed in all BC patients, bilaterally in 3 cases: 74/179 axillae had metastases. P-SPECT showed a significantly higher overall sensitivity than SPECT and planar (93.2% vs 85.1% and 36.5%, respectively; p&lt;0.05 and p&lt;0.0005, respectively) and was false negative in 5 patients with 1 metastatic node each, micrometastatic in 4/5 cases; SPECT and planar were also false negative in these 5 cases and in 6 and in 42 further cases, respectively. P-SPECT added important prognostic information by distinguishing single from multiple and pound 3 from &gt;3 nodes; only P-SPECT defined the exact number of nodes in 15/25 patients with 2-4 nodes. P-SPECT showed the highest accuracy and NPV: 92.7% and 95%, respectively (SPECT 90.5% and 90%, respectively; planar 73.2% and 68.9%, respectively). CONCLUSION: (99m)Tc-tetrofosmin axillary P-SPECT appears highly accurate in BC non palpable axillary lymph node metastasis detection and significantly more sensitive than both planar and SPECT, its few false negative results predominantly concerning micrometastases; moreover, only P-SPECT gave additional important prognostic information. Given its very high NPV, P-SPECT could also be used to better select patients who might avoid ALND

Comparison of two neural network classifiers in the differential diagnosis of essential tremor and Parkinson’s disease by ¹²³I-FP-CIT brain SPECT

Purpose : To contribute to the differentiation of Parkinson’s disease (PD) and essential tremor (ET), we compared two different artificial neural network classifiers using 123I-FP-CIT SPECT data, a probabilistic neural network (PNN) and a classification tree (ClT). Methods: 123I-FP-CIT brain SPECT with semiquantitative analysis was performed in 216 patients: 89 with ET, 64 with PD with a Hoehn and Yahr (H&amp;Y) score of ≤2 (early PD), and 63 with PD with a H&amp;Y score of ≥2.5 (advanced PD). For each of the 1,000 experiments carried out, 108 patients were randomly selected as the PNN training set, while the remaining 108 validated the trained PNN, and the percentage of the validation data correctly classified in the three groups of patients was computed. The expected performance of an “average performance PNN” was evaluated. In analogy, for ClT 1,000 classification trees with similar structures were generated. Results: For PNN, the probability of correct classification in patients with early PD was 81.9±8.1% (mean±SD), in patients with advanced PD 78.9±8.1%, and in ET patients 96.6±2.6%. For ClT, the first decision rule gave a mean value for the putamen of 5.99, which resulted in a probability of correct classification of 93.5±3.4%. This means that patients with putamen values &gt;5.99 were classified as having ET, while patients with putamen values &lt;5.99 were classified as having PD. Furthermore, if the caudate nucleus value was higher than 6.97 patients were classified as having early PD (probability 69.8±5.3%), and if the value was &lt;6.97 patients were classified as having advanced PD (probability 88.1%±8.8%). Conclusion: These results confirm that PNN achieved valid classification results. Furthermore, ClT provided reliable cut-off values able to differentiate ET and PD of different severities

^99mTc-tetrofosmin SPET in the detection of both primary breast cancer and axillary lymph node metastasis

The aim of this study was to evaluate the usefulness of 99mTc-tetrofosmin single-photon emission tomography (SPET) in the detection of both primary breast cancer and axillary lymph node metastasis. We studied 192 consecutive patients in whom primary breast cancer was suspected on the basis of mammography and/or physical examination. After intravenous injection of 740 MBq 99mTc-tetrofosmin, both planar and SPET scintimammography was performed in all patients using a rectangular dual-head gamma camera equipped with low-energy, high-resolution, parallel-hole collimators. In 175 patients with breast cancer at histology, the per-lesion overall sensitivity of SPET and planar imaging for the detection of breast cancer was 95.8% and 75.9% (P&lt;0.0005), respectively. The sensitivity of SPET and planar imaging was, respectively, 96.5% and 79.5% in palpable (P&lt;0.0005) and 90% and 45% in non-palpable lesions (P&lt;0.01). With regard to lesion size, the sensitivity of SPET and planar imaging was, respectively, 90.5% and 45.2% in lesions h10 mm (P&lt;0.0005), 95.3% and 81.4% in lesions of 11-20 mm (P&lt;0.005), 100% and 84.6% in lesions of 21-30 mm (P&lt;0.05) and 100% and 95.8% in lesions &gt;30 mm (P&gt;0.05). In the remaining 17 patients with benign mammary lesions at histology, per-lesion overall specificity of SPET and planar imaging was 76.2% and 85.7% (P&gt;0.05), respectively. Neither SPET nor planar imaging showed false-positive results in non-palpable lesions or in those h10 mm. In 173 breast cancer patients submitted to axillary lymph node dissection (ALND), per-axilla overall sensitivity of SPET and planar imaging in the detection of axillary lymph node metastasis was 93% and 52.3% (P&lt;0.0005), respectively. The sensitivity of SPET and planar imaging was, respectively, 100% and 82.6% in palpable nodes (P&gt;0.05), 90.5% and 41.3% in non-palpable nodes (P&lt;0.0005), 92.8% and 35.7% in the presence of h3 nodes (P&lt;0.0005) and 93.2% and 68.2% in the presence of &gt;3 nodes (P6lt;0.005). The specificity of SPET and planar imaging was 91% and 100% (P&lt;0.05), respectively. 99mTc-tetrofosmin SPET appears to be a reliable method for the detection of both primary BC and axillary lymph node metastasis, and its diagnostic accuracy exceeds that of 99mTc-tetrofosmin planar scintimammography. The use of SPET is particularly important in the identification of small non-palpable primary carcinomas and metastatic axillae with ≤3 non-palpable lymph nodes. More extensive use of SPET appears warranted in the management of breast cancer patients