Beyond Visual Assessment of Basal Ganglia Uptake: Can Automated Method and Pineal Body Uptake Assessment Improve Identification of Nigrostriatal Dysfunction on 18F-DOPA PET/CT?

The interpretation of 18F-DOPA PET/CT performed for assessing nigrostriatal dysfunction (NSD) is usually based on visual assessment of the uptake in the basal ganglia (VA-BG). In the present study, we evaluate the diagnostic performance of an automated method that assesses BG uptake (AM-BG) and of methods that assess pineal body uptake, and examine whether these methods can enhance the diagnostic performance of VA-BG alone. We retrospectively included 112 scans performed in patients with clinically suspected NSD who also had a subsequent final clinical diagnosis provided by a movement disorder specialist (69 NSD and 43 non-NSD patients). All scans were categorized as positive or negative based on (1) VA-BG, (2) AM-BG, and (3) qualitative and semiquantitative assessment of pineal body uptake. VA-BG, AM-BG, assessment of pineal body 18F-DOPA uptake by VA (uptake > background), by SUVmax (≥0.72), and by pineal to occipital ratio (POR ≥ 1.57) could all significantly differentiate NSD from non-NSD patients (Pv < 0.01 for all five methods). Of these methods, VA-BG provided the highest sensitivity (88.4%) and accuracy (90.2%). Combining VA-BG with AM-BG did not improve diagnostic accuracy. An interpretation algorithm that combines VA-BG with pineal body uptake assessment by POR calculation increased sensitivity to 98.5%, at the expense of decreased specificity. In conclusion, an automated method that assesses 18F-DOPA uptake in the BG and assessment of pineal body 18F-DOPA uptake can significantly separate NSD from non-NSD patients, with apparent inferior diagnostic performance when applied alone compared with VA-BG. When VA-BG categorizes a scan as negative or equivocal, assessment of the 18F-DOPA uptake in the pineal body has the potential to minimize the rate of false negative reports. Further research is essential to validate this approach and to study the pathophysiologic relationship between 18F-DOPA uptake in the pineal body and nigrostriatal dysfunction.

Aberrant dopamine transporter and functional connectivity patterns in LRRK2 and GBA mutation carriers

Non-manifesting carriers (NMCs) of Parkinson’s disease (PD)-related mutations such as LRRK2 and GBA are at an increased risk for developing PD. Dopamine transporter (DaT)-spectral positron emission computed tomography is widely used for capturing functional nigrostriatal dopaminergic activity. However, it does not reflect other ongoing neuronal processes; especially in the prodromal stages of the disease. Resting-state fMRI (rs-fMRI) has been proposed as a mode for assessing functional alterations associated with PD, but its relation to dopaminergic deficiency remains unclear. We aimed to study the association between presynaptic striatal dopamine uptake and functional connectivity (FC) patterns among healthy first-degree relatives of PD patients with mutations in LRRK2 and GBA genes. N = 85 healthy first-degree subjects were enrolled and genotyped. All participants underwent DaT and rs-fMRI scans, as well as a comprehensive clinical assessment battery. Between-group differences in FC within striatal regions were investigated and compared with striatal binding ratios (SBR). N = 26 GBA-NMCs, N = 25 LRRK2-NMCs, and N = 34 age-matched nonmanifesting noncarriers (NM-NCs) were included in each study group based on genetic status. While genetically-defined groups were similar across clinical measures, LRRK2-NMCs demonstrated lower SBR in the right putamen compared with NM-NCs, and higher right putamen FC compared to GBA-NMCs. In this group, higher striatal FC was associated with increased risk for PD. The observed differential SBR and FC patterns among LRRK2-NMCs and GBA-NMCs indicate that DaTscan and FC assessments might offer a more sensitive prediction of the risk for PD in the pre-clinical stages of the disease.

[METABOLIC AND DOPAMINERGIC BRAIN FUNCTIONAL IMAGING IN DEMENTIA WITH LEWY BODIES]

Dementia with Lewy bodies (DLB) is the second most common neurodegenerative dementia of the elderly. Its early diagnosis is a clinical challenge due to overlapping symptoms of various neurodegenerative diseases. Early diagnosis is essential for patient management avoiding neuroleptic medications that harbor the risk of causing further deterioration. Functional imaging allows accurate diagnosis and improves the degree of confidence in the diagnosis. Its advantage is based on the ability to identify biochemical changes that precede structural changes, thereby providing valuable information at early stages of the disease. Another advantage is its ability to provide a non-invasive neurobiological evaluation as well as an objective follow-up algorithm. We present a patient with cognitive and motor decline, in which anatomical imaging (MRI) failed to recognize a specific morphological abnormality. Combined data of two PET-CT brain scans using two different radiotracers raised the diagnosis of DLB. Cortical metabolism was obtained by PET with labeled glucose (FDG) and the dopaminergic activity by labeled precursor (F-DOPA) of the neurotransmitter Dopamine. In times to come, with the development of novel specific tracers, diagnostic confidence is expected to improve, along with development of new approaches of therapy.

Ga-PSMA PET/CT Staging of Newly Diagnosed Intermediate- and High-Risk Prostate Cancer

BACKGROUND

Ga-prostate-specific membrane antigen positron emission tomography/computerized tomography (Ga-PSMA PET/CT) is part of the initial workup of patients with intermediate and high-risk prostate cancer provided by the Israeli national health services.

OBJECTIVES

To assess the incidence of metastatic spread in consecutive patients with newly diagnosed cancer, and the potential added value of Ga-PSMA PET/CT to the staging imaging algorithm.

METHODS

Patients with newly diagnosed intermediate- and high-risk prostate cancer were referred for initial staging by Ga-PSMA PET/CT between May 2016 and April 2017. Blood prostate-specific antigen (PSA) levels, clinical history, imaging reports and histopathological reports (including Gleason scores) were obtained. Maximal standardized uptake values (SUVmax) were determined for the primary lesions detected within the prostate.

RESULTS

The study included 137 consecutive patients with intermediate- and high-risk disease who underwent Ga-PSMA PET/CT staging. Of these, 75 had Ga-PSMA uptake in both prostate lobes, 57 had unilateral uptake, and 5 patients had no uptake. SUVmax in the primary tumor correlated significantly with PSA levels. Thirty-five patients had increased uptake compatible with metastatic disease involving lymph nodes, bone, and viscera. Twenty-seven patients had available bone scintigraphy results: 18 (69%) of their 26 bone metastases detected by Ga-PSMA PET/CT were missed on bone scintigraphy.

CONCLUSIONS

Ga-PSMA PET/CT shows promise as a sole whole-body imaging modality for assessing the presence of soft tissue and bone metastases in the setting of prostate cancer.

FDG PET Parkinson's disease-related pattern as a biomarker for clinical trials in early stage disease

Background

The development of therapeutic interventions for Parkinson disease (PD) is challenged by disease complexity and subjectivity of symptom evaluation. A Parkinson's Disease Related Pattern (PDRP) of glucose metabolism via fluorodeoxyglucose positron emission tomography (FDG-PET) has been reported to correlate with motor symptom scores and may aid the detection of disease-modifying therapeutic effects.

Objectives

We sought to independently evaluate the potential utility of the PDRP as a biomarker for clinical trials of early-stage PD.

Methods

Two machine learning approaches (Scaled Subprofile Model (SSM) and NPAIRS with Canonical Variates Analysis) were performed on FDG-PET scans from 17 healthy controls (HC) and 23 PD patients. The approaches were compared regarding discrimination of HC from PD and relationship to motor symptoms.

Results

Both classifiers discriminated HC from PD (p < 0.01, p < 0.03), and classifier scores for age- and gender- matched HC and PD correlated with Hoehn & Yahr stage (R² = 0.24, p < 0.015) and UPDRS (R² = 0.23, p < 0.018). Metabolic patterns were highly similar, with hypometabolism in parieto-occipital and prefrontal regions and hypermetabolism in cerebellum, pons, thalamus, paracentral gyrus, and lentiform nucleus relative to whole brain, consistent with the PDRP. An additional classifier was developed using only PD subjects, resulting in scores that correlated with UPDRS (R² = 0.25, p < 0.02) and Hoehn & Yahr stage (R² = 0.16, p < 0.06).

Conclusions

Two independent analyses performed in a cohort of mild PD patients replicated key features of the PDRP, confirming that FDG-PET and multivariate classification can provide an objective, sensitive biomarker of disease stage with the potential to detect treatment effects on PD progression.

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The Parkinson's disease-related pattern (PDRP) of glucose metabolic effects is demonstrated in an independent cohort of early stage PD patients.

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The PDRP pattern of metabolic changes is robust to variations in image processing and choice of classification model.

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Age-related metabolic changes show partial overlap with the PDRP, suggesting that age-adjustment is an important consideration.

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The PDRP correlates with motor function as defined by Hoehn & Yahr stage and UPDRS score.

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An additional data driven metabolic classifier highlights pattern aspects associated with early stage motor decline.

68Ga-PSMA is a novel PET-CT tracer for imaging of hepatocellular carcinoma: A prospective pilot study

Background:⁶⁸Ga-Prostate Specific Membrane Antigen (⁶⁸Ga-PSMA), a positron emission tomography (PET) tracer that was recently introduce for imaging of prostate cancer, may accumulate in other solid tumors including Hepatocellular Carcinoma (HCC). The aim of the study was to assess the potential role of ⁶⁸Ga-PSMA PET-Computed Tomography (CT) for imaging of HCC. Material and Methods: A prospective pilot study in seven patients with HCC with 41 liver lesions: 37 suspected malignant lesions (tumor lesions) and 4 regenerative nodules. For each liver lesion, uptake of ⁶⁸Ga-PSMA and ¹⁸F-FDG uptake were measured [standard uptake value (SUV) and lesion-to-liver background ratios (TBR-SUV)], and correlated with dynamic characteristics (HU and TBR-HU) obtained on contrast enhanced CT data. Immunohistochemistry staining of PSMA in the tumor tissue was analyzed in samples obtained from 5 patients with HCC and compared to control samples from 3 patients with prostate cancer. Results: Thirty-six of the 37 tumor lesions and none of the regenerative nodules showed increased ⁶⁸Ga-PSMA uptake while only 10 lesions were ¹⁸F-FDG avid. Based on contrast enhancement, tumor lesions were categorized into 27 homogeneously enhancing lesions, nine lesions with "mosaic" enhancement composed of enhancing and non-enhancing regions in the same lesion and a single non-enhancing lesion, the latter being the only non-⁶⁸Ga-PSMA avid lesion. Using the Mann-Whitney test, ⁶⁸Ga-PSMA uptake was found significantly higher in enhancing tumor areas compared to non-enhancing areas and in contrast, ¹⁸F-FDG uptake was higher in non-enhancing areas, P<0.001 for both. ⁶⁸Ga-PSMA uptake (TBR SUV_max) was found to correlate with vascularity (TBR-HU) (Spearman r=0.866, p<0.001). Immunohistochemistry showed intense intra-tumoral microvessel staining for PSMA in HCC, in contrast with cytoplasmic and membranous staining, mainly in the luminal border, in prostate cancer samples. In two of the study patients ⁶⁸Ga-PSMA PET-CT identified unexpected extrahepatic metastases. Four regenerative liver nodules showed no increased uptake of either of the PET tracers. Conclusion:⁶⁸Ga-PSMA PET-CT is superior to ¹⁸F-FDG PET-CT in imaging patients with HCC. HCC lesions are more commonly hypervascular taking up ⁶⁸Ga-PSMA in tumoral micro-vessels. ⁶⁸Ga-PSMA PET-CT is a potential novel modality for imaging patients with HCC.

Breast Imaging Utilizing Dedicated Gamma Camera and (99m)Tc-MIBI: Experience at the Tel Aviv Medical Center and Review of the Literature Breast Imaging

The scope of the current article is the clinical role of gamma cameras dedicated for breast imaging and (99m)Tc-MIBI tumor-seeking tracer, as both a screening modality among a healthy population and as a diagnostic modality in patients with breast cancer. Such cameras are now commercially available. The technology utilizing a camera composed of a NaI (Tl) detector is termed breast-specific gamma imaging. The technology of dual-headed camera composed of semiconductor cadmium zinc telluride detectors that directly converts gamma-ray energy into electronic signals is termed molecular breast imaging. Molecular breast imaging system has been installed at the Department of Nuclear medicine at the Tel Aviv Sourasky Medical Center, Tel Aviv in 2009. The article reviews the literature well as our own experience.

The Value of PET/CT in Detecting Bone Marrow Involvement in Patients With Follicular Lymphoma

Follicular lymphoma (FL) is the 2nd most common type of lymphoma diagnosed in the Western World. Bone marrow (BM) involvement is an adverse prognostic factor in FL, routinely assessed by an arbitrary biopsy of the iliac crest. This study was aimed to investigate the role of positron emission tomography/computed tomography (PET/CT) in identifying BM involvement by FL. In this retrospective, single-center study we reviewed the records of consecutive patients with FL at diagnosis or relapse who underwent staging/restaging workup visual assessment of BM uptake was categorized as either normal, diffusely increased, or focally increased. Quantitative BM fluorine-18-fluro-deoxyglucose (FDG) uptake was measured using mean standardized uptake value (BM-SUVmean). The diagnosis of BM involvement was based on either BM histological findings or disappearance of increased uptake at end-treatment PET/CT in patients who responded to treatment. Sixty eight cases with FL were included. Sixteen (23.5%) had BM involvement, 13 (19.1%) had a biopsy proven involvement, and 3 (4.4%) had a negative BM biopsy, but increased medullary uptake that normalized post-treatment. BM FDG uptake in these patients was diffuse in 8 (50%) and focal in 8 (50%). Focal increased uptake was indicative of BM involvement; however, diffuse uptake was associated with 17 false positive cases (32.7%). Overall, visual assessment of BM involvement had a negative predictive value (NPV) of 100% and a positive predictive value (PPV) of 48.5%. On a quantitative assessment, BM-SUVmean was significantly higher in patients with BM involvement (SUVmean of 3.7 [1.7-6] vs 1.4 [0.4-2.65], P < 0.001). On receiver operator curve (ROC) analysis, BM-SUVmean > 2.7 had a PPV of 100% for BM involvement (sensitivity of 68%), while BM-SUVmean < 1.7 had an NPV of 100% (specificity of 73%). Visual assessment of PET/CT is appropriate for ruling out BM involvement by FL. Although focal increased uptake indicates marrow involvement, diffuse uptake is nonspecific. SUV measurement improves PET/CT diagnostic accuracy, identifying additional 19% of patients with BM involvement that would have been otherwise missed.

(99m)Tc-MDP bone scintigraphy of the hand: comparing the use of novel cadmium zinc telluride (CZT) and routine NaI(Tl) detectors

Background

Cadmium zinc telluride (CZT) solid-state detectors have been recently introduced in the field of nuclear medicine in cardiology and breast imaging. The aim of the current study was to evaluate the performance of the novel detectors (CZT) compared to that of the routine NaI(Tl) in bone scintigraphy. A dual-headed CZT-based camera dedicated originally to breast imaging has been used, and in view of the limited size of the detectors, the hands were chosen as the organ for assessment. This is a clinical study.

Methods

Fifty-eight consecutive patients (total 116 hands) referred for bone scan for suspected hand pathology gave their informed consent to have two acquisitions, using the routine camera and the CZT-based camera. The latter was divided into full-dose full-acquisition time (FD CZT) and reduced-dose short-acquisition time (RD CZT) on CZT technology, so three image sets were available for analysis. Data analysis included comparing the detection of hot lesions and identification of the metacarpophalangeal, proximal interphalangeal, and distal interphalangeal joints.

Results

A total of 69 hot lesions were detected on the CZT image sets; of these, 61 were identified as focal sites of uptake on NaI(Tl) data. On FD CZT data, 385 joints were identified compared to 168 on NaI(Tl) data (p < 0.001). There was no statistically significant difference in delineation of joints between FD and RD CZT data as the latter identified 383 joints.

Conclusions

Bone scintigraphy using a CZT-based gamma camera is associated with improved lesion detection and anatomic definition. The superior physical characteristics of this technique raised a potential reduction in administered dose and/or acquisition time without compromising image quality.

Attenuation of cue-induced smoking urges and brain reward activity in smokers treated successfully with bupropion

Twenty-two regular smokers (15+ cigarettes per day) were treated with bupropion and group therapy for 2 months. Subjects underwent positron emission tomography (PET) studies using measures of brain global and regional glucose metabolism (regional cerebral metabolic rates of glucose [rCMRglc]) with [18F]-Fluorodeoxyglucose (FDG) twice, after watching a videotape showing smoking scenes and after watching a control movie in counter-balanced order. A questionnaire of smoking urges (QSU) was filled in before and after watching both the movies. Changes in brain metabolic rates of FDG were analysed using Statistical Parametric Maps (SPM 2) in 11 smokers who abstained from smoking in comparison with 11 smokers who continued to smoke during the second month of treatment. Still-smokers had higher craving scores after watching the videotape showing smoking scenes compared with non-smokers. Second, watching the videotape showing smoking scenes compared with the control videotape in still-smokers resulted in increased metabolic rates in the striatum, thalamus and midbrain. Third, the ratings of the urge to smoke cigarettes while watching the videotape showing smoking scenes in still-smokers were associated with brain metabolic activity in the ventral striatum, anterior cingulate, orbitofrontal cortex, middle temporal lobe, hippocampus, insula, midbrain and thalamus. In conclusion, successfully treated smokers showed attenuated craving and reduced activity in the mesolimbic reward circuit.

A study investigating the acute dose-response effects of 13 mg and 17 mg Delta 9- tetrahydrocannabinol on cognitive-motor skills, subjective and autonomic measures in regular users of marijuana

Heavy use of marijuana is claimed to damage critical skills related to short-term memory, visual scanning and attention. Motor skills and driving safety may be compromised by the acute effects of marijuana. The aim of this study was to investigate the acute effects of 13 mg and 17 mg Delta 9-tetrahydrocannabinol (THC) on skills important for coordinated movement and driving and on subjective and autonomic measures in regular users of marijuana. Fourteen regular users of marijuana were enrolled. Each subject was tested on two separate days. On each test day, subjects smoked two low-nicotine cigarettes, one with and the other without THC. Seventeen mg THC was included in the cigarette on one test day and 13 mg on the other day. The sequence of cigarette types was unknown to the subject. During smoking, heart rate and blood pressure were monitored, and the subjects performed a virtual reality maze task requiring attention and motor coordination, followed by 3 other cognitive tasks (Wisconsin Card Sorting Test (WCST), a "gambling" task and estimation of time and distance from an approaching car). After smoking a cigarette with 17 mg THC, regular marijuana users hit the walls more often on the virtual maze task than after smoking cigarettes without THC; this effect was not seen in patients after they smoked cigarettes with 13 mg THC. Performance in the WCST was affected with 17 mg THC and to a lesser extent with the use of 13 mg THC. Decision making in the gambling task was affected after smoking cigarettes with 17 mg THC, but not with 13 m THC. Smoking cigarettes with 13 and 17 mg THC increased subjective ratings of pleasure and satisfaction, drug "effect" and drug "high". These findings imply that smoking of 17 mg THC results in impairment of cognitive-motor skills that could be important for coordinated movement and driving, whereas the lower dose of 13 mg THC appears to cause less impairment of such skills in regular users of marijuana.

Brain imaging study of the acute effects of Delta9-tetrahydrocannabinol (THC) on attention and motor coordination in regular users of marijuana

PROCEDURE

Twelve regular users of marijuana underwent two positron emission tomography (PET) scans using [18F] Fluorodeoxyglucose (FDG), one while subject to the effects of 17 mg THC, the other without THC. In both sessions, a virtual reality maze task was performed during the FDG uptake period.

RESULTS

When subject to the effects of 17 mg THC, regular marijuana smokers hit the walls more often on the virtual maze task than without THC. Compared to results without THC, 17 mg THC increased brain metabolism during task performance in areas that are associated with motor coordination and attention in the middle and medial frontal cortices and anterior cingulate, and reduced metabolism in areas that are related to visual integration of motion in the occipital lobes.

CONCLUSION

These findings suggest that in regular marijuana users, the immediate effects of marijuana may impact on cognitive-motor skills and brain mechanisms that modulate coordinated movement and driving.

Fluorine-18 Fluorodeoxyglucose PET/CT Patterns of Extranodal Involvement in Patients with Non-Hodgkin Lymphoma and Hodgkin's Disease

Lymphoma may originate in extranodal sites. Extranodal lymphoma may also be secondary to and accompany nodal disease. Fluorine-18 fluorodeoxyglucose (18F-FDG) imaging has an essential role in the staging of lymphoma, in monitoring the response to therapy, and in detection of recurrence. The introduction of 18F-FDG PET/CT hybrid imaging allows for accurate localization of disease and may be specifically beneficial for the detection of unexpected extranodal sites of disease or exclusion of disease in the presence of nonspecific extranodal CT findings. Accurate staging and localization often dictate the appropriate treatment strategy in patients with lymphoma. Therefore, at any stage in the course of the disease, the potential presence of extranodal disease should be considered when interpreting 18F-FDG PET/CT studies in patients with non-Hodgkin lymphoma and Hodgkin's disease.

Improved sentinel node identification by SPECT/CT in overweight patients with breast cancer

Overweight has been reported as a cause for the nonvisualization of sentinel nodes (SNs) on preoperative planar lymphoscintigraphy in patients with breast cancer. The purpose of this study was to assess whether SPECT/CT may improve SN identification in overweight patients.

METHODS

Lymphoscintigraphy was performed in 220 consecutive patients with breast cancer. Body mass index (BMI) was calculated for each. A total of 122 patients were overweight or obese (BMI, > or = 25). Planar images and SPECT/CT images were interpreted separately, and SN identification on each of the modalities was related to BMI and to findings at surgery.

RESULTS

Planar imaging identified SNs in 171 patients (78%) with a BMI (mean +/- SD) of 25.2 +/- 4 kg/m2 and failed to do so in 49 patients (22%) with a BMI of 28 +/- 8 kg/m2. In 29 of the latter patients (59%), SNs were identified on SPECT/CT. SPECT/CT detected "hot" nodes in 200 patients (91%) and failed to do so in 20 patients with a BMI of 29.2 +/- 6.6 kg/m2. For the 122 overweight or obese patients, planar assessment failed to identify SNs in 34 patients (28%) and SPECT/CT failed to do so in 13 patients (11%) (P < 0.001). For 116 patients, surgery took place in our hospital (Tel-Aviv Sourasky Medical Center). An intraoperative blue dye technique failed to detect SNs in 48 patients (41%) with a BMI of 28.2 +/- 7 kg/m2. SPECT/CT localized hot nodes in 36 (75%) of the latter patients, and planar imaging did so in 22 (46%) of those patients. Of 19 patients for whom scintigraphy failed, 6 (32%) had nodal metastatic involvement.

CONCLUSION

The addition of SPECT/CT to lymphoscintigraphy improved SN identification in overweight patients with breast cancer. Moreover, SPECT/CT accurately identified SNs in 75% of patients for whom the identification of SNs by the intraoperative blue dye technique failed.

SPECT/multislice low-dose CT: a clinically relevant constituent in the imaging algorithm of nononcologic patients referred for bone scintigraphy

The purpose of this prospective study was to assess the role of SPECT/multislice low-dose (Msl) CT as a constituent in the imaging algorithm of nononcologic patients referred for 99mTc-methylene diphosphonate bone scintigraphy (BS).

METHODS

SPECT/CT was performed using a novel hybrid system, which incorporates a gamma-camera and a multislice low-dose CT, on 76 consecutive nononcologic patients with nonspecific scintigraphic findings, which required further correlation with morphologic data.

RESULTS

SPECT/MslCT was of added clinical value in 89% of the patients. Characterizing scintigraphic lesions by their morphologic appearance, SPECT/MslCT reached a final diagnosis in 49 of 85 (58%) nonspecific scintigraphic bone lesions found in 59% (45/76) of patients, obviating the need to perform additional imaging. In another 30% of patients (23/76), SPECT/MslCT data optimized the patients' imaging algorithm as the performance of a full-dose CT, MRI, or labeled-leukocyte scintigraphy as the next imaging was based on its findings combined with the patient's clinical presentation.

CONCLUSION

SPECT/MslCT is a clinically relevant constituent in the imaging algorithm of nononcologic patients referred for BS.

Lymphoscintigraphy for sentinel node mapping using a hybrid single photon emission CT (SPECT)/CT system in oral cavity squamous cell carcinoma

BACKGROUND

We assessed the added clinical value of fused single photon emission computed tomography (SPECT) and low-dose CT images compared with planar images for sentinel node (SN) mapping in patients with oral cavity squamous cell carcinoma (SCC).

METHODS

Twenty consecutive patients with newly diagnosed biopsy-proven SCC of the oral cavity were enrolled. Scintigraphy was performed using a hybrid gamma-camera/low-dose CT system. Planar images and fused SPECT/CT images were interpreted separately. All patients underwent a sentinel node biopsy (SNB) followed by a neck dissection. All SNs underwent meticulous pathologic examination and immunohistochemistry staining (cytokeratin complex) in addition to routine pathologic examinations of the neck dissection specimen.

RESULTS

The sensitivity for the detection of nodal metastases was 87.5%. SPECT/CT improved SN identification and/or localization compared with planar images in 6 patients (30%).

CONCLUSIONS

SPECT/CT SN mapping provides additional preoperative data of clinical relevance to SNB in patients with oral cavity SCC.

The presentation of malignant tumours and pre-malignant lesions incidentally found on PET-CT

PURPOSE

The purpose of the study was to determine the general and organ-specific presentation of incidental primary tumours on PET-CT.

METHODS

PET-CT reports of 2,360 consecutive patients were reviewed and revealed 156 lesions suspicious for a new unexpected malignancy, in 151 patients. One hundred and twenty of these lesions, in 115 patients, were further assessed, by biopsy (n=84 patients) or by clinical and imaging follow-up (n=31 patients) for a mean of 17+/-4 months (range 12-25 months).

RESULTS

Forty-four unexpected malignancies were found in 41 of the study patients (1.7%). Twenty-seven of the 44 incidental tumours were identified on the basis of their location, which was uncommon for metastasis of the known malignancy. Eight were detected as a result of either the difference in FDG avidity of the known malignancy and the incidental lesion or the presence of an incidental non-FDG-avid mass on the CT part of the study. Four tumours were synchronous carcinomas in patients with known colorectal malignancy, three were identified by virtue of the discordant response to treatment compared with the known primary tumour and two were detected as new sites of disease after a prolonged disease-free period. There was organ variability in the positive predictive values (PPV) of PET-CT findings for incidental primary malignancy or pre-malignant lesions: 62% for colonic lesions, 54% for lung lesions and 24% for thyroid lesions.

CONCLUSION

Incidental primary tumours may be identified on PET-CT based on their location, FDG avidity, response to therapy and time of appearance. The PET and CT parts of the study appear to complement each other and assist in identification of these incidental tumours.

The detection of bone metastases in patients with high-risk prostate cancer: 99mTc-MDP Planar bone scintigraphy, single- and multi-field-of-view SPECT, 18F-fluoride PET, and 18F-fluoride PET/CT

The aim of this study was to compare the detection of bone metastases by 99mTc-methylene diphosphonate (99mTc-MDP) planar bone scintigraphy (BS), SPECT, 18F-Fluoride PET, and 18F-Fluoride PET/CT in patients with high-risk prostate cancer.

METHODS

In a prospective study, BS and 18F-Fluoride PET/CT were performed on the same day in 44 patients with high-risk prostate cancer. In 20 of the latter patients planar BS was followed by single field-of-view (FOV) SPECT and in 24 patients by multi-FOV SPECT of the axial skeleton. Lesions were interpreted separately on each of the 4 modalities as normal, benign, equivocal, or malignant.

RESULTS

In patient-based analysis, 23 patients had skeletal metastatic spread (52%) and 21 did not. Categorizing equivocal and malignant interpretation as suggestive for malignancy, the sensitivity, specificity, positive predictive value, and negative predictive value of planar BS were 70%, 57%, 64%, and 55%, respectively, of multi-FOV SPECT were 92%, 82%, 86%, and 90%, of (18)F-Fluoride PET were 100%, 62%, 74%, and 100%, and of 18F-Fluoride PET/CT were 100% for all parameters. Using the McNemar test, 18F-Fluoride PET/CT was statistically more sensitive and more specific than planar or SPECT BS (P < 0.05) and more specific than 18F-Fluoride PET (P < 0.001). SPECT was statistically more sensitive and more specific than planar BS (P < 0.05) but was less sensitive than 18F-Fluoride PET (P < 0.05). In lesion-based analysis, 156 lesions with increased uptake of 18F-Fluoride were assessed. Based on the corresponding appearance on CT, lesions were categorized by PET/CT as benign (n = 99), osteoblastic metastasis (n = 46), or equivocal when CT was normal (n = 11). Of the 156 18F-Fluoride lesions, 81 lesions (52%), including 34 metastases, were overlooked with normal appearance on planar BS. SPECT identified 62% of the lesions overlooked by planar BS. 18F-Fluoride PET/CT was more sensitive and more specific than BS (P < 0.001) and more specific than PET alone (P < 0.001).

CONCLUSION

18F-Fluoride PET/CT is a highly sensitive and specific modality for detection of bone metastases in patients with high-risk prostate cancer. It is more specific than 18F-Fluoride PET alone and more sensitive and specific than planar and SPECT BS. Detection of bone metastases is improved by SPECT compared with planar BS and by 18F-Fluoride PET compared with SPECT. This added value of 18F-Fluoride PET/CT may beneficially impact the clinical management of patients with high-risk prostate cancer.

PET-CT findings in surgically transposed ovaries

The aim of this study is to present the PET/CT findings of surgically transposed ovaries. PET/CT studies and associated abdominal imaging studies of seven women, aged 28-43 years, with 11 transposed ovaries were retrospectively reviewed. Attention was directed to the location and the 18F-Fluorodeoxyglucose (FDG) avidity of the transposed ovaries. On the CT part of the PET/CT, location of the transposed ovaries was in the ipsilateral iliac fossa or paracolic gutter abutting the anterior aspect of the ipsilateral colon (n = 6), posterolateral to the cecum (n = 4) and in the anterior abdominal cavity (n = 1). Ovaries were of soft-tissue density (n = 10 with a hypodense region in two) and one was cystic. In three patients, the transposed ovary was associated with increased FDG uptake with standard uptake values ranging from 2.4 to 4.8. Two of the latter patients had more than one PET/CT study. FDG uptake altered between studies, probably related to the performance of the study on different phases of the cycle. Menstrual history in one of the patients confirmed that the study was performed at the ovulatory-phase of the cycle. To conclude, a transposed ovary may appear on a PET-CT study as a mass with occasionally increased FDG uptake that may be related to its preserved functionality. Physicians interpreting PET/CT should be aware of surgically transposed ovaries in young female patients to avoid misdiagnosing it as tumour.

18F-FDG PET/CT in the evaluation of adrenal masses

Our purpose was to evaluate the performance of (18)F-FDG PET/CT, using data from both the PET and the unenhanced CT portions of the study, in characterizing adrenal masses in oncology patients.

METHODS

One hundred seventy-five adrenal masses in 150 patients referred for (18)F-FDG PET/CT were assessed. Final diagnosis was based on histology (n = 6), imaging follow-up (n = 118) of 6-29 mo (mean, 14 mo), or morphologic imaging criteria (n = 51). Each adrenal mass was characterized by its size; its attenuation on CT, expressed by Hounsfield units (HU); and the intensity of (18)F-FDG uptake, expressed as standardized uptake value (SUV). Receiver operating characteristic curves were drawn to determine the optimal cutoff values of HU and SUV that would best discriminate between benign and malignant masses.

RESULTS

When malignant lesions were compared with adenomas, PET data alone using an SUV cutoff of 3.1 yielded a sensitivity, specificity, positive predictive value, and negative predictive value of 98.5%, 92%, 89.3%, 98.9%, respectively. For combined PET/CT data, the sensitivity, specificity, positive predictive value, and negative predictive value were 100%, 98%, 97%, 100%, respectively. Specificity was significantly higher for PET/CT (P < 0.01). Fifty-one of the 175 masses were 1.5 cm or less in diameter. When a cutoff SUV of 3.1 was used for this group, (18)F-FDG PET/CT correctly classified all lesions.

CONCLUSION

(18)F-FDG PET/CT improves the performance of (18)F-FDG PET alone in discriminating benign from malignant adrenal lesions in oncology patients.

Lymphoscintigraphic sentinel node identification in patients with breast cancer: the role of SPECT-CT

PURPOSE

Lymph node status is a major factor in determining the stage, appropriate therapy and outcome in patients with breast cancer. It is therefore of clinical importance to accurately identify all sentinel nodes (SNs) for each individual tumour before surgery. The purpose of this study was to assess the role of SPECT-CT lymphoscintigraphy in SN identification in patients with breast cancer.

METHODS

Lymphoscintigraphy comprising planar and SPECT-CT acquisition was performed in 157 consecutive patients with breast cancer (mean age 54.7+/-10.6, range 27-81 years) with a palpable mass (n=100), with a non-palpable mass (n=52) or post lumpectomy (n=5). Planar and SPECT-CT images were interpreted separately and the two imaging techniques were compared with respect to their ability to identify hot nodes.

RESULTS

Planar imaging alone was negative for identification of hot nodes in 15% of the patients. SPECT-CT alone was negative in 10% and both techniques were negative in 9% of the patients. Forty-six of the total of 361 (13%) hot nodes identified by lymphoscintigraphy were detected only on SPECT-CT, including 21 nodes obscured by the scattered radiation from the injection site, nine adjacent nodes misinterpreted on planar images as a single node and 16 nodes which were missed on planar images and detected on SPECT data. SPECT-CT detected additional sites of drainage unexpected on planar images, including axillary (n=23 patients), internal mammary (n=5 patients), interpectoral (n=3 patients) and intramammary (n=2 patients) lymph node sites. Fourteen of the 329 (4%) hot lesions seen on planar images were false positive non-nodal sites of uptake that were accurately assessed by SPECT-CT and further validated by surgery. In a single patient, SPECT-CT was negative while planar images identified the SN.

CONCLUSION

SPECT-CT may improve the preoperative localisation of draining nodes in patients with breast cancer. It may detect hot nodes missed by planar imaging, exclude non-nodal false positive sites of uptake and accurately localise axillary and extra-axillary nodes.

Solid splenic masses: evaluation with 18F-FDG PET/CT

Our objective was to assess the role of (18)F-FDG PET/CT in the evaluation of solid splenic masses in patients with a known malignancy and in incidentally found lesions in patients without known malignancy.

METHODS

Two groups of patients were assessed: (a) 68 patients with known malignancy and a focal lesion on PET or a solid mass on CT portions of the PET/CT study; and (b) 20 patients with solid splenic masses on conventional imaging without known malignancy. The standard of reference was histology (n = 16) or imaging and clinical follow-up (n = 72). The lesion size, the presence of a single versus multiple splenic lesions, and the intensity of (18)F-FDG uptake expressed as a standardized uptake value (SUV) were recorded. The ratio of the SUV in the splenic lesion to the background normal splenic uptake was also calculated. These parameters were compared between benign and malignant lesions within each of the 2 groups of patients and between the 2 groups.

RESULTS

The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of (18)F-FDG PET/CT in differentiating benign from malignant solid splenic lesions in patients with and without malignant disease were 100%, 100%, 100%, and 100% versus 100%, 83%, 80%, and 100%, respectively. In patients with known malignant disease, an SUV threshold of 2.3 correctly differentiated benign from malignant lesions with the sensitivity, specificity, PPV, and NPV of 100%, 100%, 100%, and 100%, respectively. In patients without known malignant disease, false-positive results were due to granulomatous diseases (n = 2).

CONCLUSION

(18)F-FDG PET can reliably discriminate between benign and malignant solid splenic masses in patients with known (18)F-FDG-avid malignancy. It also appears to have a high NPV in patients with solid splenic masses, without known malignant disease. (18)F-FDG-avid splenic masses in patients without a known malignancy should be further evaluated as, in our series, 80% of them were malignant.

Coincidence imaging using 2 dual-head gamma-camera systems, with and without attenuation correction

OBJECTIVE

Coincidence imaging enhances the potential for imaging a greater number of patients with 18F-FDG in centers that do not have dedicated PET systems. The purpose of this study was to compare, in a clinical setting, coincidence imaging for tumor detection using 2 dual-head gamma-camera systems, one equipped with a 5/8-in. (16 mm) detector (CoDe5) and the other equipped with a newly designed 1-in. (25.4 mm) detector (CoDe8) with an x-ray tube installed in its gantry.

METHODS

Thirty consecutive patients were studied by both systems during the same visit and had 4 image sets for comparison: CoDe5 without attenuation correction (CoDe5NC), CoDe8 with (CoDe8AC) and without (CoDe8NC) attenuation correction, and fused coincidence-CT images. The target-to-background ratio (T/Bg ratio) and target-to-nontarget ratio (T/NT ratio) were calculated for each tumor site.

RESULTS

On visual assessment, 61 tumor sites were detected on CoDe8AC images. Of these, 59 (97%) were detected on CoDe8NC and 54 (88%) were detected on CoDe5NC images. Fused images improved image interpretation in 10 patients (33%) compared with coincidence images alone. Data added by fusion were of clinical relevance in 6 patients (20%). On quantitative assessment, the number of accepted events by the CoDe8 was significantly higher than that by CoDe5 (5.21 +/- 1.46 million vs. 1.27 +/- 0.36 million, P <0.001). When comparing CoDe5 with CoDe8 images without attenuation correction, the T/Bg and T/NT ratios were significantly higher on the CoDe8 images (P <0.0005 and P <0.0005, respectively). When comparing CoDe8 images with and without attenuation correction, the T/Bg ratio was better on the attenuation-corrected images (P <0.0005).

CONCLUSION

Coincidence imaging with 1-in. detectors and attenuation correction improve image quality and, to a lesser extent, the tumor detection rate compared with the 5/8-in. detectors and noncorrected images. The data added by fusion of coincidence images to CT findings were clinically relevant in 20% of the patients.

The diagnostic accuracy of 18F-Fluorodeoxyglucose PET/CT in patients with gynecological malignancies

OBJECTIVE

To evaluate the diagnostic accuracy of integrated positron emission tomography/computerized tomography (PET/CT) in patients with gynecological cancer.

METHODS

Fifty-three consecutive patients with gynecologic malignancies were included. The patients were referred to our tertiary center to undergo a PET/CT scan. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of PET/CT were compared with the conventional imaging assessments [CT, magnetic resonance imaging (MRI) and ultrasonography (US)].

RESULTS

All tested values were higher for PET/CT than those for the conventional modalities: sensitivity 0.97 vs. 0.40, specificity 0.94 vs. 0.65, PPV 0.97 vs. 0.70, and NPV 0.94 vs. 0.34, respectively.

CONCLUSION

PET/CT is a reliable modality for assessing the extent of disease in patients with gynecologic malignancy.

Detection of recurrence in patients with rectal cancer: PET/CT after abdominoperineal or anterior resection

PURPOSE

To assess diagnostic accuracy of combined positron emission tomography (PET) and computed tomography (CT) in detection of pelvic recurrence in patients with rectal cancer who underwent abdominoperineal or anterior resection.

MATERIALS AND METHODS

Sixty-two patients were enrolled; 37 were men, and 25 were women. Seventeen patients underwent abdominoperineal resection and 45 underwent anterior resection with an anastomosis in the pelvic region before referral for PET/CT. Pelvic sites of fluorine 18 ((18)F) fluorodeoxyglucose (FDG) uptake were rated separately on PET and PET/CT images as benign or malignant on the basis of shape, location, and intensity of (18)F FDG uptake (1-2 = benign and/or physiologic, 3 = equivocal, 4-5 = malignant). Two readers interpreted images in consensus. Altered pelvic anatomy and presence of presacral abnormalities were assessed with CT. Pelvic recurrence was confirmed with histologic analysis or clinical and imaging follow-up. Sensitivity, specificity, positive and negative predictive values, and accuracy of PET and PET/CT in the detection of pelvic recurrence were compared with lesion- and patient-based analyses by using the chi(2) test. Clinical relevance of PET/CT assessment was determined.

RESULTS

Of 81 pelvic sites with increased (18)F FDG uptake, 44 were malignant. Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy for differentiating malignant from benign (18)F FDG uptake in the pelvis were 98%, 96%, 90%, 97%, and 93% for PET/CT and 82%, 65%, 73%, 75%, and 74% for PET, respectively. The most common cause for false-positive interpretation of PET findings was physiologic (18)F FDG uptake in displaced pelvic organs. Presacral CT abnormalities were present in 30 (48%) of 62 patients, and seven (23%) abnormalities were malignant. PET/CT was used to distinguish benign and malignant presacral abnormalities with a sensitivity, specificity, positive predictive value, and negative predictive value of 100%, 96%, 88%, and 100%, respectively. PET/CT findings were clinically relevant in 29 (47%) of 62 patients.

CONCLUSION

PET/CT is an accurate technique in the detection of pelvic recurrence after surgical removal of rectal cancer.

The clinical impact of camera-based positron emission tomography imaging in patients with recurrent colorectal cancer

RATIONALE AND OBJECTIVES

F18-fluorodeoxyglucose (FDG)-positron emission tomography (PET) studies have clinical value in suspected recurrent or metastatic colorectal cancer cases. Because this modality is not accessible for many patients, a camera-based FDG (CB-FDG) coincidence imaging was suggested as an alternative. Although inferior in resolution to a dedicated PET system, it can make FDG studies available to more patients. We assessed the clinical value of CB-FDG in patients with recurrent colorectal cancer.

METHODS

The disease stage and treatment approach in 83 patients were twice determined by an oncologist and a surgeon, first based on the patient's records and blind to CB-FDG findings and then with the inclusion of FDG results in the decision-making analysis.

RESULTS

On a lesion-based analysis, the sensitivity of CB-FDG was 95% and the specificity was 81% compared with 88% and 64%, respectively, for computed tomography. Adding FDG findings led to disease-stage alteration in 47 patients (57%), upstaging in 35 (42%), and downstaging in 12 (15%). FDG localized the tumor sites in 21 of 26 patients (81%) with suspected clinical recurrence and a negative conventional imaging workup. In 8 patients, FDG ruled out viable tumor tissue suggested by other modalities. The oncologist's suggested treatment approach was altered in 54% of the patients and the surgeon altered the decision on operability in 28%.

CONCLUSION

CB-FDG assessment has clinical value for both staging and selecting treatment in patients with recurrent colorectal cancer and can be considered an alternative to an nonaccessible dedicated PET system.

Normal and abnormal 18F-FDG endometrial and ovarian uptake in pre- and postmenopausal patients: assessment by PET/CT

The purpose of the study was to assess physiologic endometrial (18)F-FDG uptake during the 4 phases of the menstrual cycle and to differentiate between physiologic and malignant endometrial uptake.

METHODS

Endometrial (18)F-FDG uptake, expressed as standardized uptake value (SUV), was measured on PET/CT images of 285 consecutive female patients, of whom 246 (112 premenopausal and 134 postmenopausal) had no known gynecologic malignancy and 39 (14 premenopausal and 25 postmenopausal) had cervical, endometrial, or ovarian cancer.

RESULTS

Two peaks of increased endometrial (18)F-FDG uptake were identified during the 4-phase cycle. The mean SUVs were 5 +/- 3.2 and 3.7 +/- 0.9 in menstruating and ovulating patients, respectively, and 2.6 +/- 1.1 and 2.5 +/- 1.1 in patients in the proliferative and secretory phases, respectively. The mean endometrial SUV in postmenopausal patients not receiving hormonal therapy was 1.7 +/- 0.5. Oligomenorrhea and benign endometrial abnormalities were associated with increased (18)F-FDG uptake. Neither contraceptives nor hormonal therapy was associated with a significant increase in endometrial uptake. In addition to the increased tumor uptake measured in patients with cervical cancer (14.9 +/- 7.3 in postmenopausal patients and 12.2 +/- 6.6 in premenopausal patients), increased uptake was also found in the adjacent endometrium, although it appeared normal on CT (4.8 +/- 2 in premenopausal patients and 4.7 +/- 2.8 in postmenopausal patients). Increased ovarian (18)F-FDG uptake was detected in 7 patients with ovarian cancer (9.1 +/- 4) and in 21 premenopausal patients without known ovarian malignancy (5.7 +/- 1.5, P < 0.01), of whom 15 were at mid cycle and 3 reported oligomenorrhea. An ovarian SUV of 7.9 separated benign from malignant uptake with a sensitivity of 57% and a specificity of 95%.

CONCLUSION

In premenopausal patients, normal endometrial uptake of (18)F-FDG changes cyclically, increasing during the ovulatory and menstrual phases. Increased uptake in the endometrium adjacent to a cervical tumor does not necessarily reflect endometrial tumor invasion. Increased ovarian uptake in postmenopausal patients is associated with malignancy, whereas increased ovarian uptake may be functional in premenopausal patients.

Assessment of malignant skeletal disease: initial experience with 18F-fluoride PET/CT and comparison between 18F-fluoride PET and 18F-fluoride PET/CT

18F-fluoride PET/CT was performed on 44 oncologic patients to evaluate its diagnostic accuracy in assessing malignant osseous involvement and in differentiating malignant from benign bone lesions.

METHODS

(18)F-fluoride PET and (18)F-fluoride PET/CT were interpreted separately. Lesions showing increased (18)F-fluoride uptake were categorized as malignant, benign, or inconclusive. The final diagnosis of lesions was based on histopathology, correlation with contemporaneous diagnostic CT or MRI, or clinical follow-up of at least 6 mo (mean, 10 +/- 3 mo).

RESULTS

Increased (18)F-fluoride uptake was detected at 212 sites, including 111 malignant lesions, 89 benign lesions, and 12 lesions for which the final diagnosis could not be determined. In a lesion-based analysis, the sensitivity of PET alone in differentiating benign from malignant bone lesions was 72% when inconclusive lesions were considered false negative and 90% when inconclusive lesions were considered true positive. On PET/CT, 94 of 111 (85%) metastases presented as sites of increased uptake with corresponding lytic or sclerotic changes, and 16 of the 17 remaining metastases showed normal-appearing bone on CT, for an overall sensitivity of 99% for tumor detection. For only 1 metastasis was PET/CT misleading, suggesting the false diagnosis of a benign lesion. The specificity of PET/CT was significantly higher than that of PET alone (97% vs. 72%, P < 0.001). PET/CT identified benign abnormalities at the location exactly corresponding to the scintigraphic increased uptake for 85 of 89 (96%) benign lesions. In a patient-based analysis, the sensitivity of PET and PET/CT was 88% and 100%, respectively (P < 0.05) and the specificity was 56% and 88%, respectively (not statistically significant). Among the 12 patients referred for (18)F-fluoride assessment because of bone pain despite negative findings on (99m)Tc-methylene diphosphonate bone scintigraphy, (18)F-fluoride PET/CT suggested malignant bone involvement in all 4 patients with proven skeletal metastases, a potential benign cause in 4 of 7 patients who had no evidence of metastatic disease, and a soft-tissue tumor mass invading a sacral foramen in 1 patient.

CONCLUSION

The results indicate that (18)F-fluoride PET/CT is both sensitive and specific for the detection of lytic and sclerotic malignant lesions. It accurately differentiated malignant from benign bone lesions and possibly assisted in identifying a potential cause for bone pain in oncologic patients. For most lesions, the anatomic data provided by the low-dose CT of the PET/CT study obviates the performance of full-dose diagnostic CT for correlation purposes.

Malignant involvement of the spine: assessment by 18F-FDG PET/CT

The purpose of the study was to assess the role of (18)F-FDG PET/CT in the assessment of secondary malignant involvement of the spinal column.

METHODS

In 51 patients, 242 lesions at the spinal region detected on (18)F-FDG PET/CT were interpreted separately on PET, CT, and fused PET/CT images, including differentiation between benign and malignant lesions and the level in the vertebral column. CT evaluation also included the type of bony lesion (osteolytic, osteoblastic, or mixed) and accompanying soft-tissue abnormalities; for example, epidural masses and tumor involvement of the neural foramina.

RESULTS

Of the 242 lesions detected on PET/CT, PET alone identified 220 lesions and CT alone identified 159; 217 (90%) were malignant and 25 benign. (18)F-FDG PET alone detected significantly more malignant lesions than did CT alone (96% vs. 68%, respectively, P < 0.001). The specificity was 56% for both PET alone and CT alone. PET alone was incorrect in determining the level of abnormality within the vertebral column in 33 (15%) lesions and in determining the part of the vertebra involved in 40 (18%) lesions. In 17 (33%) patients, either epidural extension of tumor (n = 7 lesions), neural foramen involvement of tumor (n = 7 lesions), or a combination of both (n = 11 lesions) was detected. On a patient-based analysis, the sensitivity of PET and of PET/CT for the detection of spinal metastasis was 98% and 74%, respectively (P < 0.01).

CONCLUSION

(18)F-FDG PET/CT has better specificity for detection of malignant involvement of the spine than does (18)F-FDG PET. It allows for precise localization of lesions and identifies accompanying soft-tissue involvement, which is of potential neurologic significance.

Lymphoscintigraphy for sentinel node mapping using a hybrid SPECT/CT system

Lymphoscintigraphy is performed before sentinel node (SN) biopsy for SN mapping. It is of clinical importance mainly if the tumor is located in body parts with ambiguous lymph node drainage. The purpose of this study was to assess the clinical benefit of fused SPECT/CT images to planar images for SN mapping.

METHODS

Thirty-four consecutive patients with cutaneous malignant melanoma (n = 28) and squamous cell carcinoma (n = 6) and scheduled for SN biopsy were enrolled. Primary tumors were located in the trunk (n = 12), in the extremities (n = 12), in the head and neck (n = 9), and in the penis (n = 1). Scintigraphy was performed using a hybrid gamma-camera/low-dose CT system. Planar images and fused SPECT/CT images were interpreted separately.

RESULTS

SPECT/CT identified multiple draining basins in 6 of 12 patients (50%) with trunk melanoma and in 3 of 9 patients (33%) with head and neck melanoma or mucosal tumor. In 9 of 21 patients (43%) with a primary tumor located in the head and neck or trunk region, SPECT/CT-fused images identified SNs that were missed on planar images, 2 of which were involved with tumor. Three of the 9 nodes were located close to the injection site and were hidden by its scattered radiation, and 2 were in-transit nodes. Another 4 nodes, identified on fused images only, were located in an additional basin to those identified on planar images. Fused images were of no added value either in patients with limb melanoma or in a patient with a penile melanoma.

CONCLUSION

SPECT/CT SN mapping provides additional data that are of clinical relevance to SN biopsy in patients with trunk or head and neck melanoma and in patients with mucosal head and neck tumor.

Bone injury associated with anterior cruciate ligament and meniscal tears: assessment with bone single photon emission computed tomography

RATIONALE AND OBJECTIVES

Acute injury of the menisci and ligaments about the knee joint is often associated with accompanying bone injury. The role of bone single photon emission computed tomography (SPECT) was assessed in this clinical setting.

MATERIALS AND METHODS

Knee SPECT was performed in 94 patients with suspected ACL, meniscal tear, or both and was correlated with arthroscopy (n = 74), magnetic resonance imaging (MRI) (n = 37), or both. Scintigraphic findings were categorized based on their anatomic location and on uptake intensity (0-3 grade scale).

RESULTS

Correlation with arthroscopy: Eleven patients had a normal arthroscopy of which in 10, SPECT images detected no abnormality. Sixty-three patients had abnormal arthroscopic findings, whereas all had abnormal SPECT studies. Thirty-eight patients had an anterior cruciate ligament (ACL) tear on arthroscopy. In this type of injury SPECT images detected increased uptake in the posterior aspect of the lateral tibial plateau (LTPp) with a positive predictive value (PPV) of 93% and a negative predictive value (NPV) of 97%. In 55% of the patients, increased uptake was also detected in the region of the middle sulcus of the lateral femoral condyle (LFCm): a "kissing" pattern. Tear of the medial meniscus was diagnosed by arthroscopy in 43 patients. SPECT images detected increased uptake in the medial tibial plateau (MTP) with a PPV of 78% and a NPV of 83%. Correlation with MRI: all seven cortical fractures seen on MRI were detected on SPECT. Twenty-eight patients had MRI findings suggestive of an ACL injury. Accompanying bone bruises were seen in 18 of them (64%). On SPECT images, all 28 patients with an ACL tear had increased uptake in the LTPp. Intensity of uptake in patients with associated bone bruise, however, was significantly higher; mean intensity grade 2.4 +/- 0.7 in case of accompanying bone bruise compared with 1.4 +/- 0.8 in case of an ACL tear without associated bone injury, P< 0.01.

CONCLUSION

Results of the study suggest that bone SPECT is valuable in acute knee trauma for assessment of ACL, meniscal tears, or both and for detection of associated bone injury.

Role of (18)F-FDG dual-head gamma-camera coincidence imaging in recurrent or metastatic colorectal carcinoma

(18)F-FDG PET has been shown to be of high diagnostic accuracy for the evaluation of recurrent colorectal cancer. However, the limited availability of PET scanners precludes (18)F-FDG assessment of many patients for whom the study is indicated. An alternative is the SPECT system in coincidence mode. The aim of this study was to determine the role of dual-head camera (18)F-FDG coincidence imaging (DHC (18)F-FDG) in patients with recurrent colorectal cancer.

METHODS

Sixty-seven DHC (18)F-FDG studies were performed on 62 patients with suspected recurrent colorectal cancer. Reports of contemporary CT were available for the purpose of correlation for 61 of the studies. The final diagnosis of the imaging findings was based on histology or clinical and imaging follow-up of at least 6 mo.

RESULTS

In lesion-based analysis, 103 tumor sites were suspected on DHC (18)F-FDG, CT, or colonoscopy. Ninety-three of them were found to be true tumor sites. For DHC (18)F-FDG, the sensitivity was 88%, specificity was 80%, positive predictive value (PPV) was 98%, negative predictive value (NPV) was 42%, and accuracy was 87%. For CT, the sensitivity was 63%, specificity was 10%, PPV was 85%, NPV was 3%, and accuracy was 57%. In patient-based analysis, DHC (18)F-FDG differentiated patients with recurrent cancer from disease-free patients with a sensitivity of 91%, specificity of 73%, PPV of 94%, NPV of 62%, and accuracy of 88%. DHC (18)F-FDG detected tumor sites in 12 (67%) of 18 patients with elevated carcinoembryonic antigen and negative CT findings.

CONCLUSION

DHC (18)F-FDG is an adequate readily available technique for assessment of recurrent colorectal cancer and has a diagnostic accuracy better than that of CT.

Kidney allografts and remaining contralateral donor kidneys before and after transplantation: assessment by quantitative (99m)Tc-DMSA SPECT

We used (99m)Tc-dimercaptosuccinic acid (DMSA) quantitative SPECT (QDMSA) to assess the function of kidneys before harvesting and after transplantation as well as the function of remaining donor kidneys.

METHODS

Nineteen kidney donors underwent a baseline QDMSA study before nephrectomy. The allografts of these kidneys were studied in recipients at 1 wk, 1-2 mo, and 6-15 mo after transplantation. The kidneys remaining in 16 donors were studied at 1-2 mo and 6-15 mo after harvesting. The parameters obtained in each SPECT study included functional volume, concentration of (99m)Tc-DMSA per cubic centimeter of renal tissue, and total kidney uptake. Clinical evaluation and determination of serum creatinine levels took place at the same time as SPECT.

RESULTS

On the basis of the clinical evaluation, 14 grafts had normal function and 5 were impaired. The mean +/- SD of kidney uptake values expressed as percentage of baseline values were 131% +/- 30% in normal grafts versus 57% +/- 5% in impaired grafts at 1 wk (P < 0.01), 173% +/- 57% versus 65% +/- 10% at 1-2 mo (P < 0.001), and 190% +/- 50% versus 69% +/- 14% at 6-15 mo after transplantation (P < 0.01). Uptake values in the donors' remaining kidneys were 159% +/- 27% of baseline values at 1-2 mo and 164% +/- 30% at 6-15 mo after nephrectomy. Allografts and remaining kidneys showed a similar increase in total kidney uptake as a result of an increase in both functional volume and concentration.

CONCLUSION

QDMSA may be a noninvasive assessment tool in kidney transplantation from living donors.

Bone scan and bone biopsy in the detection of skeletal metastases

This study provides the first quantitative indication of the limits of sensitivity of a bone scan with technetium (99Tc-MDP) in detecting skeletal metastases and thereby also helps to explain the fact that bone scans may be negative when metastases are present in the bone marrow. Since 99Tc-MDP remains the least noxious and most widely used isotope for bone scanning, these results have direct clinical relevance in the evaluation of patients with solid tumors and possible metastatic spread.

Skin grafting in the Syrian hamster. A modified technic

SYNOPSIS IN INTERLINGUA

GRAFFOS CUTANEE IN HAMSTERS SYRIAN: UN TECHNICA MODIFICATE.—Il es difficile excider con cisorios un pecia circlar de pelle de approximativemente 10 mm de diametro pro un graffo a spissitate integre. Mantener le graffo in sito per medio de bandages o suturas es indesirabile. Un ronde punciator-forcipe bioptic de 8 mm excideva graffos que es perfectemente ronde, de spissitate integre, e identic in dimensiones. Un spargitura Rezifilm manteneva le graffo in sito de maniera satistactori. Le graffos se adjustava perfectemente e esseva retenite sin imbrication e sin le presentia de exponite tissu subcutanee.