(18)F-FDG-PET Scanning Confirmed Infected Intracardiac Device-Leads with Abiotrophia defectiva.

Abiotrophia species are relatively slow growing pathogens, which may be present as commensal flora. However, invasive infections are frequently reported, like endocarditis, septic arthritis, osteomyelitis, and many other types of infection. In this case report we describe a 65-year-old male patient with an intracardiac device- (ICD-) lead infection caused by Abiotrophia defectiva. Diagnosis was confirmed by (18)F-FDG-PET scanning. This is remarkable, since Abiotrophia defectiva is a slow growing pathogen causing low-grade infections. This case demonstrates that although infection of ICD-leads cannot be excluded in case of (18)F-FDG-PET-negative findings, positive findings are highly suggestive for infection.

¹²³I-MIBG heart-to-mediastinum ratio is influenced by high-energy photon penetration of collimator septa from liver and lung activity.

AIM: The 123I-metaiodobenzylguanidine (123I-MIBG) late heart-to-mediastinum ratio (H/M) is a well-established prognostic parameter in patients with chronic heart failure (CHF). However, 123I presents imaging problems owing to high-energy photon emission leading to penetration of collimator septa and subsequent reduction in image quality. Most likely this affects the H/M ratio and may subsequently lead to incorrect patient risk classification. In this prospective study we assessed the intrapatient variation in late H/M ratio between low-energy high-resolution (LEHR) and medium-energy (ME) collimators in patients with CHF. MATERIALS AND METHODS: Fifty-three patients with CHF (87% male, age 63±8.3 years, left ventricular ejection fraction 29±7.8) referred for 123I-MIBG scintigraphy were enrolled in the study. In each patient, after the administration of 185 MBq I-MIBG, early (15 min after injection) and late (4 h after injection) planar anterior thoracic images were acquired with both LEHR and ME collimators. Early and late H/M ratios were calculated on the basis of the mean count densities from the manually drawn regions of interest (ROIs) over the left ventricle and a predefined fixed ROI placed in the upper mediastinum. Additional ROIs were drawn over the liver and lungs. Liver/lung to myocardium and liver/lung to mediastinal ratios were calculated to estimate the effect of collimator septa penetration from liver and lung activity on the myocardial and mediastinal ROIs. RESULTS: The mean LEHR collimator-derived parameters were lower compared with those from the ME collimator (late H/M 1.41±0.18 vs. 1.80±0.41, P<0.001). Moreover, Bland-Altman analysis showed that with increasing late H/M ratios the difference between the ratios from the two collimator types increased (R2=0.73, P=0.001). Multivariate regression analysis showed that almost 90% of the variation in the difference between ME and LEHR late H/M ratios could be explained by scatter from the liver in both the mediastinal and myocardial ROIs (R2=0.90, P=0.001). Independent predictors for the difference in the late H/M between ME and LEHR were the liver-to-heart ratio and the liver-to-mediastinum ratio assessed by ME (standardized coefficient of -1.69 and 1.16, respectively) and LEHR (standardized coefficient of 1.24 and -0.90, respectively) (P<0.001 for all). CONCLUSION: Intrapatient comparison in H/M between the ME and LEHR collimators in patients with CHF showed that with increasing H/M the difference between the ratios increased in favour of the ME collimator. These differences could be explained by septal penetration of high-energy photons from both the liver and the lung in the mediastinum and myocardium, being lowest when using the ME collimator. These results strengthen the importance of the recommendation to use ME collimators in semiquantitative 123I-MIBG studies.

Impact of a predefined mediastinal ROI on inter-observer variability of planar ¹²³I-MIBG heart-to-mediastinum ratio.

AIM: Purpose of this study was to assess the impact of mediastinal region of interest (ROI) definition on intra- and inter-observer variability in relation to collimator type. METHODS: Thirty-five subjects with CHF (80% men, mean age 66 ± 9 years, NYHA 2.4 ± 0.5, LVEF 29 ± 8.4%) were enrolled. 15 minutes and 4 hours post-injection (p.i.) of (123)I-MIBG, planar images were sequentially acquired with low energy high energy (LEHR) and medium energy (ME) collimators. In the first analysis, observer-defined mediastinal ROI was used. In the second analysis, a predefined mediastinal ROI was used. Intra- and inter-observer variability of late H/M was assessed using Lin's concordance coefficient (LCC). RESULTS: There was substantial agreement between all three observers using predefined mediastinum ROI. LCCs for LEHR were 0.98, 0.96, and 0.95, for ME 0.98, 0.97, and 0.97. However, observer-defined mediastinal ROI resulted in poor-moderate agreement. LCCs for LEHR were 0.82, 0.94, and 0.70, for ME 0.77, 0.91, and 0.80. Intra-observer analysis using predefined mediastinal ROI showed substantial agreement. LCC was 0.97 for LEHR and 0.96 for ME. CONCLUSION: Predefined mediastinal ROI results in low intra- and inter-observer variability of late H/M and is, therefore, to be preferred over observer-defined mediastinal ROI. Intra- and inter-observer variability of late H/M is not influenced by collimator choice.

Predictive factors of isolated tumor cells and micrometastases in axillary lymph nodes in breast cancer.

INTRODUCTION: Since the introduction of the sentinel lymph node biopsy (SLNB) in patients with breast cancer, micrometastases and isolated tumor cells are detected frequently in the SLN. As such, they offer an opportunity to study the development of regional metastases in breast cancer. PATIENTS AND METHODS: Between June 1999 and November 2010 1418 patients with cT1-2N0 breast cancer underwent SLNB. Primary tumor characteristics and information regarding regional lymph node involvement were collected prospectively. Patients were categorized into four levels of lymph node involvement: pN0, pN0(i+), pN1mi and pN ≥ 1a. An univariate analysis and a binary logistic regression analysis were performed to assess the relation between patient- and tumor characteristics and lymph node involvement. RESULTS: Increasing tumor size and younger age were associated with a higher risk of pN1mi and pN ≥ 1a and a lower chance of pN0 and pN0(i+). Triple negative molecular subtype was associated with a decreased risk of pN1mi and pN ≥ 1a. Tumor size was positively related to overall occurrence of regional lymph node metastases in a linear manner. CONCLUSION: Patients with larger tumors, no triple negative disease, and younger age showed a decreased chance of both pN0 and pN0(i+) and an increased risk of both pN1mi and pN ≥ 1a. There seems to be a gradual shift in risk pattern from pN0 to pN0(i+) to pN1mi and to pN ≥ 1a-disease. The presence of the smallest metastases remained fairly constant over time when compared to macrometastases. This constant presence suggests that the risk of seeding and outgrowth of metastases remains constant over time.

Ultrasound-guided sentinel node procedure for nonpalpable breast carcinoma.

PURPOSE: Peritumoral and periareolar tracer injection techniques lead to different lymphatic drainage in sentinel lymph node biopsy procedures. In a prospective study, the visualization and identification rates of the ultrasound (US)-guided tracer injection technique for palpable and nonpalpable breast tumors were evaluated. METHODS: In 1262 consecutive patients with cT1₋2N0 breast cancer, sentinel lymph node biopsy was performed following peritumoral tracer injection. In the case of nonpalpable breast lesions, Tc-99m nanocolloid injections were given using a 7.5 MHz US probe. In the case of ultrasonographically nonvisible microcalcifications, the US-guided injection technique was wire guided. RESULTS: In 331 patients with nonpalpable breast lesions (26.2%), the lymphoscintigraphic visualization and surgical retrieval rates of axillary sentinel lymph nodes (SLNs) were 98.5 and 99.4%, respectively. For internal mammary (IM) SLNs, these rates were 21.1 and 17.8%, respectively. These rates were similar in patients with palpable and nonpalpable tumors. Axillary metastases were detected in 38.7% of the patients with palpable tumors versus 16.5% of those with nonpalpable tumors (P<0.001), whereas IM metastases were found in 4.8 and 3.0% of patients, respectively (P=0.165). CONCLUSION: In nonpalpable breast lesions, the US-guided injection technique is an accurate technique for SLN identification and retrieval. The substantial rates of IM metastases in both palpable and nonpalpable lesions favor a peritumoral tracer injection technique.

Prognostic value of lymph node micrometastases in breast cancer: a multicenter cohort study.

BACKGROUND: To evaluate the prognostic meaning of lymph node micrometastases in breast cancer patients. METHODS: Between January 2000 and January 2003, 1411 patients with a cT(1-2)N(0) invasive breast carcinoma underwent surgery in 7 hospitals in the Netherlands. Sentinel lymph node biopsy was done in all patients. Based on lymph node status, patients were divided into 4 groups: (p)N(0) (n = 922), (p)N(1micro) (n = 103), (p)N(1a) (n = 285), and (p)N(≥1b) (n = 101). Median follow-up was 6.4 years. RESULTS: At the end of follow-up, 1121 women were still alive (79.4%), 184 had died (13.0%), and 106 were lost to follow-up (7.5%). Breast cancer recurred in 244 patients: distant metastasis (n = 165), locoregional relapse (n = 83), and contralateral breast cancer (n = 44). Following adjustment for possible confounding characteristics and for adjuvant systemic treatment, overall survival (OS) remained comparable for (p)N(0) and (p)N(1micro) and was significantly worse for (p)N(1a) and (p)N(≥1b) (hazard ratio [HR] 1.18; 95% confidence interval [95% CI] 0.58-2.39, HR 2.47; 95% CI 1.69-3.63, HR 4.36; 95% CI 2.70-7.04, respectively). Disease-free survival (DFS) was similar too in the (p)N(0) and (p)N(1micro) group, and worse for (p)N(1a) and (p)N(≥1b) (HR 0.96; 95% CI 0.56-1.67 vs HR 1.64; 95% CI 1.19-2.27, HR 2.95; CI 1.98-4.42). The distant metastases rate also did not differ significantly between the (p)N(0) and (p)N(1micro) group and was worse for (p)N(1a) and (p)N(≥1b) (HR 1.22; 95% CI 0.60-2.49, HR 2.26; 95% CI 1.49-3.40, HR 3.49; CI 2.12-5.77). CONCLUSIONS: In breast cancer patients survival is not affected by the presence of micrometastatic lymph node involvement.

FDG PET in lymphoma: the need for standardization of interpretation. An observer variation study.

OBJECTIVE: To measure and describe patterns of interobserver variation in visual interpretation of 18-FDG PET in malignant lymphoma. METHODS: Eleven nuclear medicine physicians with different levels of PET experience independently reviewed 37 18F-FDG PET scans of lymphoma patients (10 obtained at presentation, 27 during or after therapy). They were requested to identify and localize suspicious lymphoma sites and to assign a stage to the baseline scans, and to interpret the remaining scans for the presence of viable lymphoma. Individual (extra-)nodal regions were assessed for the likelihood of malignancy as positive, negative or equivocal. These results were compared to expert readings after dichotomization in conservative and sensitive reading classifications. RESULTS: Sixty-one percent and 56% (using sensitive and conservative reading, respectively) of the baseline scans were scored in accordance with the experts. Fourteen of the 27 scans obtained for therapy evaluation with viable tumour sites were scored in accordance with the experts in 82% and 94% of the patients, using conservative and sensitive reading, respectively. The 13 negative scans were scored in agreement with the experts in only 45% of the cases. False positivity pertained especially to the neck, periclavicular, axilla, mediastinum, lung and bone marrow. More experienced observers tended to have fewer false negative scores. CONCLUSION: There are substantial disparities among nuclear medicine physicians' interpretations of FDG PET scans of lymphoma patients, which may affect patient care and results of multi-institutional clinical trials. A well-defined set of criteria is urgently needed to improve consistency.

The use of scintimammography for detecting the recurrence of loco-regional breast cancer: histopathologically proven results.

BACKGROUND: 99mTc tetrofosmin scintimammography has been shown to be an accurate diagnostic test in patients with a symptomatic breast lesion and for whom a non-diagnostic mammogram has been obtained. Since a physical examination and conventional imaging modalities have their limitations in the detection of recurrent breast cancer, and survival is related to the extent of recurrent disease, complementary imaging modalities are warranted. AIM: To evaluate the role of 99mTc tetrofosmin scintimammography in detecting the recurrence of loco-regional breast cancer. PATIENTS AND METHODS: Fifty-four patients underwent 55 scintimammography studies because either there were clinical indications of breast metastases, or there was a recurrence of metastases in the chest wall, and/or an evaluation of axillary, parasternal, supraclavicular and/or infraclavicular lymph node metastases was required. Planar breast imaging was performed 10 min after intravenous injection of 700 MBq 99mTc tetrofosmin. RESULTS: 99mTc tetrofosmin scintimammography was diagnostic in 50 of the 55 studies. An unknown lung metastasis was detected in one patient, and an unknown bone metastasis of the sternum was detected in another. Tumour involvement remained undetected in one neck node metastasis. Three patients had false positive scintimammography results, with 99mTc tetrofosmin uptake in an axillary, infraclavicular and parasternal lymph node, respectively. A fourth patient showed 99mTc tetrofosmin uptake in the scar, which appeared to be an inflammatory lesion, proven by a histopathological biopsy and 1 year clinical follow-up. CONCLUSION: 99mTc tetrofosmin scintimammography accurately detected 100% of the local recurrences independently of the extent of the preceding surgical intervention. The sensitivity and specificity of the technique for the detection of regional recurrent disease were 93% and 90%, respectively. These results are substantially higher than those of other imaging modalities.

Cost-effectiveness of dual-head 18F-fluorodeoxyglucose PET for the detection of recurrent laryngeal cancer.

The study is based upon 80 patients, suspected of having recurrent laryngeal cancer, who underwent an 18F-FDG PET study on a coincidence camera and a laryngoscopic biopsy under general anaesthesia. The potential value of 18F-FDG PET in the detection of local relapses of laryngeal cancer after radiotherapy by use of a coincidence camera was prospectively assessed, and a cost-effectiveness analysis was performed retrospectively. The effectiveness of 18F-FDG PET is reflected in sensitivity and specificity, positive predictive value (PPV) and negative predictive value (NPV) using comparison with the biopsy results as a gold standard. In case of a negative biopsy result, follow-up was continued for a minimum of one year. The results showed a sensitivity of 100%, a specificity of 85%, a PPV of 87%, and a NPV of 100%. Costs per patient of a 18F-FDG PET scan were 682 euro, whereas the saved costs by reducing CT-scans and panendoscopies were 618 euro. In this scenario implementation of 18F-FDG PET scintigraphy in the detection of recurrent laryngeal cancer has additional costs of 64 euro per patient. However, panendoscopy related complications, and potential improvement in quality of life due to early detection of recurrent disease were not taken into account in this study. In conclusion, the technical efficacy of 18F-FDG PET in the detection of recurrent laryngeal cancer is high. 18F-FDG PET is more accurate than CT, and in addition the cost-effectiveness ratio of 18F-FDG PET lies within an acceptable range and has further improvement potential when a quality of life factor is included in a prospective cost-effectiveness analysis.