Plasma Phosphorylated Tau 231 Increases at One-Year Intervals in Cognitively Unimpaired Subjects

Background

Plasma biomarkers of Alzheimer's disease (AD) constitute a non-invasive tool for diagnosing and classifying subjects. They change even in preclinical stages, but it is necessary to understand their properties so they can be helpful in a clinical context.

Objective

With this work we want to study the evolution of p-tau231 plasma levels in the preclinical stages of AD and its relationship with both cognitive and imaging parameters.

Methods

We evaluated plasma phosphorylated (p)-tau231 levels in 146 cognitively unimpaired subjects in sequential visits. We performed a Linear Mixed-effects Model to analyze their rate of change. We also correlated their baseline levels with cognitive tests and structural and functional image values. ATN status was defined based on cerebrospinal fluid biomarkers.

Results

Plasma p-tau231 showed a significant rate of change over time. It correlated negatively with memory tests only in amyloid-positive subjects. No significant correlations were found with any imaging measures.

Conclusions

Increases in plasma p-tau231 can be detected at one-year intervals in cognitively healthy subjects. It could constitute a sensitive marker for detecting early signs of neuronal network impairment by amyloid.

Where Should I Draw the Line: PET-Driven, Data-Driven, or Manufacturer Cut-Off?

Background

The optimal cut-off for Alzheimer's disease (AD) CSF biomarkers remains controversial.

Objective

To analyze the performance of cut-off points standardized by three methods: one that optimized the agreement between 11C-Pittsburgh compound B PET (a-PET) and CSF biomarkers (Aβ1-42, pTau, tTau, and Aβ1-42/Aβ1-40 ratio) in our population, called PET-driven; an unbiased cut-off using data from a healthy research cohort, called data-driven, and that provided by the manufacturer. We also compare changes in ATN classification.

Methods

CSF biomarkers measured by the LUMIPULSE G600II platform and qualitative visualization of amyloid positron emission tomography (a-PET) were performed in all the patients. We established a cut-off for each single biomarker and Aβ1-42/Aβ1-40 ratio that optimized their agreement with a-PET using ROC curves. Sensitivity, Specificity, and Overall Percent of Agreement are assessed using a-PET or clinical diagnosis as gold standard for every cut-off. Also, we established a data-driven cut-off from our cognitively unimpaired cohort. We then analyzed changes in ATN classification.

Results

One hundred and ten patients were recruited. Sixty-six (60%) were a-PET positive. PET-driven cut-offs were: pTau > 57, tTau > 362.62, Aβ1-42/Aβ1-40 < 0.069. For a single biomarker, pTau showed the highest accuracy (AUC 0.926). New PET-driven cut-offs classified patients similarly to manufacturer cut-offs (only two patients changed). However, 20 patients (18%) changed when data-driven cut-offs were used.

Conclusions

We established our sample's best CSF biomarkers cut-offs using a-PET as the gold standard. These cut-offs categorize better symptomatic subjects than data-driven in ATN classification, but they are very similar to the manufacturer's.

Erdheim-Chester Disease Due to a Novel Internal Duplication of NRAS: Response to Targeted Therapy with Cobimetinib

Histiocytoses encompass a group of exceptionally rare disorders characterized by the abnormal infiltration of tissues by histocytes. Among these, Erdheim-Chester disease (ECD) stands out as a multisystem histiocytosis that typically affects bones and various other tissues. Historically, the treatment of ECD has been challenging. However, recent breakthroughs in our understanding, particularly the discovery of somatic mutations in the RAS-MAPK pathway, have opened new opportunities for targeted therapy in a significant subset of patients with ECD and other histiocytoses. In this report, we present the case of a patient with ECD harboring a previously unidentified microduplication in the NRAS gene in a small fraction of skin cells. This discovery played a pivotal role in tailoring an effective therapeutic approach involving kinase inhibitors downstream of NRAS. This case underscores the crucial role of deep sequencing of tissue samples in ECD, enabling the delivery of personalized targeted therapy to patients.

Utility of Amyloid and FDG-PET in Clinical Practice: Differences Between Secondary and Tertiary Care Memory Units

The clinical utility of amyloid positron emission tomography (PET) has not been fully established. Our aim was to evaluate the effect of amyloid imaging on clinical decision making in a secondary care unit and compare our results with a previous study in a tertiary center following the same methods. We reviewed retrospectively 151 cognitively impaired patients who underwent amyloid (Pittsburgh compound B [PiB]) PET and were evaluated clinically before and after the scan in a secondary care unit. One hundred and fifty concurrently underwent fluorodeoxyglucose (FDG)-PET. We assessed changes between the pre- and post-PET clinical diagnosis and Alzheimer's disease treatment plan. The association between PiB/FDG results and changes in management was evaluated using χ2 and multivariate logistic regression. Concordance between classification based on scan readings and baseline diagnosis was 66% for PiB and 47% for FDG. The primary diagnosis changed after PET in 17.2% of cases. When examined independently, discordant PiB and discordant FDG were both associated with diagnostic change (p < 0.0001). However, when examined together in a multivariate logistic regression, only discordant PiB remained significant (p = 0.0002). Changes in treatment were associated with concordant PiB (p = 0.009) while FDG had no effect on treatment decisions. Based on our regression model, patients with diagnostic dilemmas, a suspected non-amyloid syndrome, and Clinical Dementia Rating <1 were more likely to benefit from amyloid PET due to a higher likelihood of diagnostic change. We found that changes in diagnosis after PET in our secondary center almost doubled those of our previous analysis of a tertiary unit (9% versus 17.2%). Our results offer some clues about the rational use of amyloid PET in a secondary care memory unit stressing its utility in mild cognitive impairment patients.

Fluorine-18-fluorodeoxyglucose positron emission tomography/computed tomography in a giant left pectoral muscle plasmacytoma and multiple myeloma case

Extramedullary plasmacytoma is an unusual manifestation in multiple myeloma (MM). It can present as a solitary bone lesion and/or soft-tissue mass. Plasmacytoma can be presented at any location, but it is more common in the head and neck, usually without systemic involvement. The presence of plasmacytoma in MM is a predictor of rapidly progressive disease. The value of fluorine-18-fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (PET-FDG) is increasing, in the diagnosis, detection of occult lesions, and therapeutic monitoring. We describe a patient with rapidly-progressive, refractory, left pectoral muscle plasmacytoma and MM. A PET-FDG guided the therapy and allowed to identify the presence of disease relapse.

Contribution of 11C-Choline PET/CT in prostate carcinoma biochemical relapse with serum PSA level below 1 ng/ml

OBJECTIVE

¹¹C-choline PET/CT has demonstrated good results in the restaging of prostate cancer (PCa) with high serum prostate specific antigen (PSA), but its use in patients with low serum PSA is controversial. Our aim was to evaluate the contribution of ¹¹C-choline PET/CT in patients with PCa, biochemical relapse and PSA <1 ng/ml.

MATERIAL AND METHOD

Fifty consecutive patients (mean age: 65.9±5.6 years) with biochemical relapse of PCa and serum PSA <1ng/ml were evaluated retrospectively. PET/CT was performed 20min after intravenous administration of 555-740 MBq of ¹¹C-choline. Minimum follow up time was 30 months.

RESULTS

Twenty-one out of 50 patients (42%) had an abnormal ¹¹C-choline PET/CT. In 7 out of 21 patients (14%) tumor was confirmed (4 in prostatic bed, 4 in pelvic lymph nodes, 2 in mediastinal lymph nodes and one synchronous sigmoid carcinoma), and in all cases the initial therapeutic planning was modified. In 2 patients (4%) subsequent tests diagnosed a benign disease (one sarcoidosis, one tuberculosis sequelae) and in 3 patients (6%) they ruled out pathology. The other 9 patients (18%) had no further assessment (7 mediastinal and 4 pelvic lymph nodes). Twenty-nine out of 50 patients (58%) had a normal PET/CT. At 30 months, follow up recurrence was confirmed only in 2 of these patients.

CONCLUSIONS

¹¹C-choline PET/CT proved its usefulness in demonstrating tumor in 14% of patients with BR of PCa and serum PSA <1ng/ml, with therapeutic implications. In 4% of patients a benign condition was detected. A normal ¹¹C-choline PET/CT was associated with a very low rate of recurrence at 30 months.

Candida Esophagitis Incidentally Detected by 18F-FDG PET/CT in Metastatic Lung Adenocarcinoma

The diagnostic significance of esophageal 18F-FDG uptake in oncologic patient is challenging. It may represent normal physiological uptake, inflammation, infection, or neoplasia. We present a patient with a recent diagnosis of non-small cell lung cancer stage IV and esophageal mild uptake on 18F-FDG PET/CT scan. Biopsy of esophageal mucosa demonstrated Candida esophagitis.

The Role of PET/CT Molecular Imaging in the Diagnosis of Recurrence and Surveillance of Patients Treated for Non-Small Cell Lung Cancer

Non-small cell lung cancer (NSCLC) is the leading cause of cancer mortality worldwide and its prognosis remains poor. Molecular imaging with ¹⁸F-FDG PET/CT can metabolically characterize the nature of lesions as benign or malignant, allowing a better staging at the diagnosis of this kind of patient. This advantage can also be applied in the re-staging due to the suspicion of recurrent disease. Many patients have a recurrence of the disease, including surgically treated patients. In the current context, with new personalized oncological treatments, the surveillance for recurrence and its accurate diagnosis are crucial to improve their survival. In this paper, we revise the current knowledge about the clinical and molecular factors related to the recurrent disease. In the context of new, promising, available personalized treatments, the role of molecular imaging with PET/CT and ¹⁸F-FDG and non-¹⁸F-FDG radiotracers in the follow-up of NSCLC-treated patients is especially attractive and interesting.

Ventilation/Perfusion SPECT lung scintigraphy and computed tomography pulmonary angiography in patients with clinical suspicion of pulmonary embolism

The aim was to compare ventilation/perfusion SPECT lung scintigraphy (V/Q-SPECT) and computed tomography pulmonary angiography (CTPA) in patients with suspicion of pulmonary embolism (PE).

MATERIAL AND METHODS

This prospectively designed study included 53 patients with intermediate or high clinical probability of PE. A V/Q-SPECT and CTPA was performed on all patients. The V/Q-SPECT was interpreted according to the European Association of Nuclear Medicine and Molecular Imaging (EANMMI) guidelines. CTPA was reported as positive, negative, or indeterminate.

RESULTS

CTPA was positive in 22 cases, negative in 28, and indeterminate in 3. V/Q-SPECT was positive in 27 cases, negative in 24, and non-diagnostic in 2. In the 22 with positive CTPA, V/Q-SPECT was positive in 18, negative in 3, and non-diagnostic in 1. In the 28 with negative CTPA, V/Q-SPECT was positive in 8, negative in 19, and non-diagnostic in 1. In the 3 with indeterminate CTPA, V/Q-SPECT was positive in 1 and negative in 2. In the 2 non-diagnostic cases V/Q-SPECT, CTPA was positive in 1 and negative in one. In the 10 high clinical probabilities, CTPA and V/Q-SPECT were positive in 7, negative in 2, and in 1, CTPA was positive and V/Q-SPECT negative. In the 38 intermediate probability group, CTPA and V/Q-SPECT were positive in 11, negative in 17, with CTPA negative and V/Q-SPECT positive in 8, and in 2 CTPA was positive and V/Q-SPECT negative. The results show that V/Q-SPECT detected PE in 5 patients more than CTPA.

CONCLUSION

Our results show a 77% concordance of both techniques. Overall V/Q-SPECT detected PE in 18% more patients than CTPA in the intermediate group. Both techniques have a complementary role when a diagnosis cannot be made with one of them.

Patterns of 11C-PIB cerebral retention in mild cognitive impairment patients

OBJECTIVE

To evaluate the patterns of cerebral cortical distribution of (11)C-PIB in patients with mild cognitive impairment (MCI).

MATERIAL AND METHODS

The study included 69 patients (37 male, age range 42-79 years) with MCI, sub-classified as 53 with amnestic-MCI (A-MCI), and 16 with non-amnestic-MCI (NA-MCI). Patients underwent (11)C-PIB PET/CT scan 60min after intravenous injection of the radiotracer. A visual analysis of the images was performed by 2 experienced physicians. (11)C-PIB-positive studies were considered when gray matter uptake was equal to or greater than white matter. According to the regions involved, (11)C-PIB-positive studies were classified into A-pattern (predominant retention in frontal, anterior cingulate, lateral temporal, and basal ganglia) and B-pattern (generalized retention).

RESULTS

Thirty-nine of the 69 (56%) patients with MCI showed (11)C-PIB retention. Of the 53 A-MCI patients, 36 (68%) showed (11)C-PIB retention. Eleven out of 36 (30%) positive scans in A-MCI patients showed A-pattern, and 25 out of 36 (70%) patients had a B-pattern. Positive (11)C-PIB was observed in 3 out of 16 (19%) patients with NA-MCI. Regional distribution in these 3 patients showed A-pattern in 1, and B-pattern in 2 patients.

CONCLUSION

Cortical retention of (11)C-PIB was more frequent in A-MCI than in NA-MCI patients, and also B-pattern than A-pattern in the (11)C-PIB positive group. The recognition of (11)C-PIB distribution patterns allows MCI patients to be classified, and the A-pattern may offer a therapeutic window for potential future treatments.

(18)F-FDG PET/CT for the detection of large vessel vasculitis in patients with polymyalgia rheumatica

PURPOSE

Polymyalgia rheumatica (PMR) may present together with large vessel vasculitis (LVV), and frequently requires a more intensive therapy. The aim of the study was to evaluate the impact of (18)F-FDG PET/CT in the diagnosis and management of LVV associated to PMR.

MATERIAL AND METHODS

This prospective study included 40 consecutive patients (27 women/13 men, 68.10±10.27 years) with PMR and suspicion of associated LVV submitted for (18)F-FDG PET/CT. A PET/CT scan was obtained 180 min after (18)F-FDG intravenous injection. A visual analysis was performed on the images. Five vascular regions were evaluated: supra-aortic trunks (SAT), thoracic aorta (TA), abdominal aorta (AA), iliac arteries (IA), and femoral/tibioperoneal arteries (FTA). The intensity of uptake was graded from 0 to 3. A final diagnosis of LVV was established in 26/40 patients (65%).

RESULTS

In the 26 patients with a diagnosis of LVV, the highest intensity of (18)F-FDG uptake was observed in the TA, SAT, and FTA. All of these patients showed uptake at the TA, with grade 2 and 3 in most cases. In 4 of the 14 patients without LVV, no uptake was observed in any vascular region, and in the other 10 patients only a grade 1 uptake was observed in 1 or to 2 territories. Out of the 20 treated LVV patients, (18)F-FDG PET/CT led to a therapeutic change in 17 (85%).

CONCLUSION

(18)F-FDG PET/CT was useful in identifying patients with LVV associated to PMR. The detection of vascular inflammation had an important impact, and led to a change of treatment in a high percentage of patients with LVV.

Contribution of V/Q SPECT to planar scintigraphy in the diagnosis of pulmonary embolism

AIM

To evaluate the feasibility of V/Q SPECT and analyze its contribution to planar V/Q lung scintigraphy in the diagnosis of pulmonary embolism (PE).

MATERIAL AND METHODS

A total of 109 patients with suspected PE showing Wells score>2 and elevated D-dimer were studied. The V/Q could not be completed in 7 patients, so they were excluded. Ventilation and perfusion scans were done using Technegas and (99m)Tc-MAA. Planar study included 8 projections on a 256×256 matrix and 128 projections on a 128×128 matrix were acquired for the SPECT study, applying an iterative method. Planar images were interpreted according to modified PIOPED criteria, and SPECT by the guidelines of the EANMMI. The results with both techniques were compared.

RESULTS

V/Q planar scintigraphy and SPECT could be performed in 102 patients. V/Q planar scintigraphy was considered "diagnostic" in 39 of the 102 patients, and "non-diagnostic" in 63. Of the 39 "diagnostic" studies, 31 were reported as high probability of PE and 8 as normal. Of the 63 "non-diagnostic", 26 corresponded to intermediate, 29 to low, and 8 to very low probability. The SPECT study was "diagnostic" in 97 and indeterminate in only 5. All patients with a high probability planar scintigraphy had a positive SPECT. In the 8 patients with a normal planar scintigraphy SPECT was negative in 5 and positive in 3. In the 63 patients with a "non-diagnostic" planar scintigraphy SPECT was "diagnostic" in 58 of them, positive in 17 and negative in 41.

CONCLUSION

V/Q SPECT is a feasible technique as it was performed in 102 of the 109 patients who were enrolled in the study (94%). The addition of V/Q SPECT to planar V/Q decreases the number of "non-diagnostic" reports from 62% in planar scintigraphy to 4.9% in SPECT. Therefore, V/Q SPECT should be included in the diagnosis approach of PE due to its high diagnostic yield.

Comparison of 99mTc-sestamibi and 11C-methionine PET/CT in the localization of parathyroid adenomas in primary hyperparathyroidism

AIM

To evaluate the usefulness of (11)C-methionine PET/CT (MET) in the localization of the parathyroid adenomas and to compare the results with those obtained with the conventional technique in double-phase (99m)Tc-sestamibi scintigraphy (MIBI). We evaluated the optimal timing to acquire MET images.

MATERIAL AND METHODS

A prospective study that included 14 patients (mean age: 65.5 ± 9.7 years) with primary hyperparathyroidism (PH) who underwent surgery was performed. Mean serum iPTH was 215.8 ± 108 pg/mL and serum calcium 10.8 ± 0.9 mg/dL. MIBI (planar and SPECT) was obtained 10 min and 2-3h after injection of 740 MBq (20 mCi) of (99m)Tc-sestamibi. MET was obtained 10 min and 40 min after injection of 740 MBq (20 mCi) of (11)C-methionine. MIBI and MET images were visually evaluated and compared. A score for 10 min and 40 min MET images from 0 (no abnormal uptake) to 3 (intense uptake) was assigned.

RESULTS

MIBI and MET were positive and concordant in 11/14 patients and in 10 of them the parathyroid adenoma was correctly localized. In 3/14 MIBI was positive and MET negative (MIBI correctly localized the parathyroid adenoma in 2 of them). According to the timing of MET imaging acquisition, the 10 min and 40 min acquisition showed the same score in 10 patients, it was higher at 10 min acquisition in 3 and in 1 the parathyroid adenoma was only detected at 40 min acquisition.

CONCLUSION

MIBI remains the technique of choice for the localization of parathyroid adenomas in patients with PH. MET may play a complementary role in selected patients. Delayed acquisition should be included in the MET protocol when the early acquisition is negative.

Evaluation of the contribution of the dynamic phase of lymphoscintigraphy to the detection of sentinel lymph node in breast cancer

AIM

The aim of this study was to evaluate the contribution of an early dynamic phase (DP) of the lymphoscintigraphy (LS) to the detection of the sentinel lymph node (SLN) in breast cancer.

METHODS

This prospective study included 164 breast lesions in 161 consecutive patients (160 women, mean age 57.5 years). Patients with tumor >5 cm, multicentric, palpable nodes, axillary involvement, previous surgery, lymphadenectomy, radio or chemotherapy were not included. All patients underwent preoperative LS before surgery. DP immediately after injection of [99mTc]Nanocolloid followed by early and delayed planar images (EPI and DPI) were acquired.

RESULTS

SLN was detected in 162/164 lesions (98.8%). In 115 (71%) DP showed no lymph node uptake and the SLN was identified only by EPI and DPI. A focal uptake by at least one lymph node was observed in DP in the remaining 47 lesions (29%). Although in 30/74 lesions DP did not provide additional information to EPI and DPI, nevertheless in 17 cases (10.5%) DP was essential to identify correctly the SLN.

CONCLUSION

We concluded that DP, by allowing a better interpretation of the lymphatic drainage pattern, provides unique information to distinguish the correct SLN from other lymph nodes and is recommended as the first part of LS.

Diagnosis of recurrence and assessment of post-recurrence survival in patients with extracranial non-small cell lung cancer evaluated by 18F-FDG PET/CT

The accurate diagnosis of recurrence of non small cell lung cancer (NSCLC) is crucial for the appropriate management of patients with suspicion of recurrence (SOR). We evaluated prospectively in the clinical setting the contribution of FDG PET/CT in patients with SOR of NSCLC in terms of sensitivity, specificity, impact on therapy and on survival.

METHODS

Of the 55 patients included in the study, recurrence was confirmed in 37 but, follow up data for survival evaluation was available in 34. There were 59 SOR in the 55 patients and in 41 recurrence was confirmed. 53 of the 59 suspicions, had a contrast enhanced CT. All patients had a FDG PET/CT scan after iv injection of 8 MBq/kg of F18-FDG.

RESULTS

Of the 59 SOR, FDG PET/CT was positive in all 41 in which recurrence was confirmed (100% sensitivity) and, it was negative in 15 of the 18 in which it was ruled out (specificity 83%). In 27 SOR with inconclusive CT, FDG PET/CT showed 100% sensitivity (18/18) and 78% specificity (7/9). FDG PET/CT had an impact on treatment in 42 of the 59 SOR. In all 34 patients, FDG PET/CT diagnosed recurrence and overall survival at 20 months and 5 years was 44% and 11%, respectively. When the extent of recurrence assessed by FDG PET/CT was considered, survival at 20 months and at 5 years of patients with loco-regional recurrence was 77% and 28% and in patients with distant recurrence 14% and 0% (p < 0.001).

CONCLUSION

Despite the small number of patients, our study demonstrates that FDG PET/CT is highly accurate for the detection of NSCLC recurrence. Therefore it has a great impact on the therapy regimen and on survival depending on the extent of the recurrent disease, survival being better for patients with local recurrence. By differentiating local from distant recurrence, it allows the selection of patients who, could potentially benefit from new therapies. The results also suggest that there are grounds to include FDG PET/CT in the guidelines for surveillance for NSCLC.

Evaluation of the contribution of the dynamic phase of lymphoscintigraphy to the detection of sentinel lymph node in breast cancer

Aim: The aim of this study was to evaluate the contribution of an early dynamic phase (DP) of the lymphoscintigraphy (LS) to the detection of the sentinel lymph node (SLN) in breast cancer. Methods: This prospective study included 164 breast lesions in 161 consecutive patients (160 women, mean age 57.5 years). Patients with tumor >5 cm, multicentric, palpable nodes, axillary involvement, previous surgery, lymphadenectomy, radio or chemotherapy were not included. All patients underwent preoperative LS before surgery. DP immediately after injection of [99mTc]Nanocolloid followed by early and delayed planar images (EPI and DPI) were acquired. Results: SLN was detected in 162/164 lesions (98.8%). In 115 (71%) DP showed no lymph node uptake and the SLN was identified only by EPI and DPI. A focal uptake by at least one lymph node was observed in DP in the remaining 47 lesions (29%). Although in 30/74 lesions DP did not provide additional information to EPI and DPI, nevertheless in 17 cases (10.5%) DP was essential to identify correctly the SLN. Conclusion: We concluded that DP, by allowing a better interpretation of the lymphatic drainage pattern, provides unique information to distinguish the correct SLN from other lymph nodes and is recommended as the first part of LS.

Contribution of 18F-sodium fluoride PET/CT to the study of the carotid atheroma calcification

AIM

To assess the calcification process of the carotid plaque by (18)F-sodium fluoride PET/CT imaging.

MATERIAL AND METHODS

A prospectively designed study including 15 patients in whom an atheroma plaque was detected by contrast enhanced CT scan during a neurological work-up was performed. A total of 29 plaques, 19 asymptomatic and 10 symptomatic, were studied. An (18)F-sodium fluoride PET/CT scan was acquired 180min after the i.v. injection of 370 MBq of (18)F-sodium fluoride in all the patients. The images obtained were analyzed visually according to the intensity of the uptake.

RESULTS

All the plaques showed (18)F-sodium fluoride uptake, regardless of the intensity. However, the plaques of the symptomatic group showed a level of 2 or greater intensity while the intensity in 6 of the 19 in the asymptomatic group was lower than 2.

CONCLUSIONS

Although the study is limited by the small number of cases, the results show the feasibility of the technique to study the calcification of the atheroma using (18)F-sodium fluoride and suggest an association between symptomatology and higher uptake of (18)F-sodium fluoride. Thus, these results encourage us to continue this study, with the inclusion of a larger number of patients.

High prevalence of upper urinary tract involvement detected by 111indium-oxine leukocyte scintigraphy in patients with candiduria

The purpose of this investigation was to assess the prevalence of upper urinary tract involvement in patients with candiduria by means of (111)indium-oxine-labeled leukocyte scintigraphy. An observational cohort study of patients with confirmed candiduria was conducted in an acute-care teaching hospital in Spain from March 2006 through February 2009. An (111)In-labeled leukocyte scan was performed in order to assess the upper urinary tract involvement. A series of non-matched patients without candiduria nor bacteriuria undergoing scintigraphy to exclude infections in other sites than the urinary tract was also studied. Demographics, baseline illness, and clinical data were recorded. Candiduria was detected in 428 patients, and scintigraphy was performed in 35 of these patients. Twenty-nine patients without candiduria nor bacteriuria were also studied. Positive renal scintigraphy was documented in 24 (68%) patients with confirmed candiduria and in 3 (10%) patients without candiduria (p < 0.005). Renal uptake was not associated with a higher mortality nor with re-admissions. Subclinical pyelonephritis could be more frequent in patients with candiduria than it has been previously considered.

[18F-FDG PET/CT in response evaluation of gastrointestinal stromal tumours treated with imatinib]

OBJECTIVE

Several studies have demonstrated the effective use of adjuvant treatment with Imatinib mesylate for unresectable, metastatic or recurrent gastrointestinal stromal tumours (GIST). We retrospectively evaluated the role of 18F-FDG PET/CT scanning in assessing the response of GIST patients to imatinib mesylate therapy.

MATERIALS AND METHODS

Eight consecutive patients with GIST confirmed by surgery (4 stomach, 2 small bowel, 1 small bowel and peritoneum, and 1 rectum) underwent eighteen 18F-FDG PET/CT imaging after beginning imatinib mesylate therapy (400 mg/day or greater if disease progression). PET/CT scan was acquired 60-90 minutes after the intravenous injection of 333-707 MBq of 18F-FDG. Visual and semiquantitative (standardized uptake value [SUV]) analysis of images was performed. Response to therapy was assessed according to EORTC recommendations for PET. Results were confirmed by clinical follow-up, radiographic findings or histological analysis.

RESULTS

Complete response to imatinib mesylate was observed in 5 patients. Four had abdominal lymph nodes, associated with liver metastases in 2, and the other had a residual tumour mass. Partial response (reduction in SUV and in the extent of FDG uptake) was demonstrated in a patient with lung nodules. Disease progression was observed in one patient who had developed new liver metastases on the PET/CT scan. One patient with multiple peritoneal implants and abdominal mass was a non-responder and died 2 months after the 18F-FDG PET/CT.

CONCLUSION

18F-FDG PET/CT scan identified the degree of GIST response to imatinib therapy. Patients who responded to therapy showed normalisation of FDG uptake or a decrease in the SUV of lesions.