Assessment of Apparent Diffusion Coefficients and SUVs as Predicators of Histological Differentiation in Anal Squamous Cell Carcinoma.

AIM: The study aims to assess minimal apparent diffusion coefficient (ADCmin) and SUVmax as predictors of histological differentiation in patients with anal squamous cell carcinoma (ASCC) and to determine cutoff values for each histopathological tumor grade. PATIENTS AND METHODS: A retrospective study of 41 ASCC patients (14 males, 27 females; mean age, 65 ± 13 years) staged with FDG PET/CT and MRI (mean scan time interval, 21 ± 11 days). SUVmax and ADCmin values were measured and compared with histopathological tumor grading obtained from biopsy. RESULTS: The mean size and tumor volume were 3 ± 2 cm and 16.5 ± 27.3 cm3, respectively. The mean ADCmin values for well-, moderately, and poorly differentiated ASCC were 935 ± 179, 896 ± 123, and 637 ± 114, respectively. The mean SUVmax for well-, moderately, and poorly differentiated ASCC were 6.9 ± 1.8, 11.5 ± 4.1, and 13.4 ± 2.6, respectively. The difference in mean ADCmin values between poorly and moderately/well-differentiated tumors was statistically significant, whereas this was not significant between moderately and well-differentiated tumors. Differences in SUVmax values were statistically significant between poorly/moderately and well-differentiated tumors, whereas there was no statistical significance between poorly and moderately differentiated tumors. By combining the 2 modalities using cutoff values of 675 × 10-6 mm2·s-1 for ADCmin and 8.5 for SUVmax, it was possible to differentiate the tumor categories with a sensitivity, specificity, positive predictive value, and negative predictive value, respectively, of 84.6%, 96.4%, 91.7%, and 93.1% for well-differentiated ASCC, 76.5%, 87.5%, 81.3%, and 84% for moderately, and 90.9%, 89.3%, 76.9%, and 96.2% for poorly differentiated ASCC, respectively. CONCLUSIONS: ADCmin and SUVmax values correlated with the degree of differentiation in ASCC and can be used as predictors of tumor grading and aggressiveness. Combined ADCmin and SUVmax cutoff values can therefore be used for early patient risk stratification and treatment decision making.

Impact of thyroiditis on 131I uptake during ablative therapy for differentiated thyroid cancer.

CONTEXT: Differentiated thyroid cancer (DTC) is usually treated by thyroidectomy followed by radioiodine ablation and generally has a good prognosis. It may now be possible to limit the amount of treatment without impacting on efficacy. It is not known whether coexistent thyroiditis impacts on radioiodine uptake or on its potential efficacy, but this could provide a rationale for modification to current therapeutic protocols. DESIGN: This was a retrospective cohort study of radioiodine uptake on imaging after radioiodine ablation for DTC in patients with and without concurrent thyroiditis. All patients with histologically confirmed DTC treated with radioiodine ablation after thyroidectomy in a single centre from 2012 to 2015 were included. The primary outcome assessed was the presence of low or no iodine uptake on post-ablation scan, as reported by a nuclear medicine physician blinded to the presence or absence of thyroiditis. RESULTS: One hundred thirty patients with available histopathology results were included. Thyroiditis was identified in 42 post-operative specimens and 15 of these patients had low or no iodine uptake on post-ablation scan, compared to only 2 of 88 patients without thyroiditis (P < 0.0001) with further data analysis dividing the groups by ablation activity received (1100 MBq or 3000 MBq). CONCLUSIONS: Concurrent thyroiditis may impair the uptake of radioactive iodine in management of DTC. Given that patients with DTC and thyroiditis already have a good prognosis, adopting a more selective approach to this step in therapy may be indicated. Large, longitudinal studies would be required to determine if omitting radioactive iodine therapy from those patients with concurrent thyroiditis has a measurable impact on mortality from thyroid cancer.

Use of 18F FDG PET and the short temporal response of Hodgkin's disease to RIT.

Radioimmunotherapy (RIT) has been available for some time to treat patients with non-Hodgkin's lymphoma, but its use in Hodgkin's lymphoma has been less available, partly because of the need to find an appropriate antibody. A new radioiodinated chimeric antibody directed against the CD25 epitope (131I basiliximab) seems promising, but assessment of response has been difficult. 18F-fluorodeoxyglucose-positron emission tomography (18F-FDG-PET) has become a standard method by which the response of Hodgkin's disease to chemotherapy is both predicted and assessed with well-understood criteria of response. The aim of this study is to determine 18F-FDG-PET can be used to assess response to RIT. Pre- and post-treatment 18F-FDG-PET imaging was performed in a series of 13 patients with advanced Hodgkin's disease who had failed conventional therapy and had been enrolled on a compassionate use program for treatment with 131I basiliximab. The 131I basiliximab was given at an activity of 1200MBq/m2 with one patient receiving 2 cycles and the rest a single cycle. The 18F-FDG-PET studies were compared using the "Deauville" criteria and by comparing the maximum standardized uptake value (SUVmax) of target tumors before and 4 and 8 weeks after treatment. All patients survived long enough for their initial 18F-FDG-PET-computed tomography scan at 4 weeks after their 131I basiliximab therapy. One out of ten patients with "Deauville" Grade 4 or 5 response died during the 6-month follow-up period. Two out of three patients with a "Deauville" Grade 2 or 3 response died in the follow-up period. The mean SUVmax pretreatment was 11.9 (±4.7); at 4-week posttreatment, the mean SUVmax was significantly lower at 6.5 (±5.8) (P = 0.02). At 8 weeks, the mean SUVmax was 8.8 (±7.0), which was not significantly different from the pretreatment level. 18F-FDG-PET imaging is able to predict the short-term response to treatment of Hodgkin's disease by RIT, and an initial poor response appears to predict poor outcome. Early changes in 18F-FDG-PET uptake did not predict sustained response and by 8 weeks all but one patient had recurrent disease.

Optimization of PET/CT image quality using the GE 'Sharp IR' point-spread function reconstruction algorithm.

OBJECTIVE: The objective of this study was to quantify any improvement with the GE 'Sharp IR' point-spread function (PSF) reconstruction algorithm in addition to ordered subsets expectation maximum (OSEM) and time-of-flight (TOF) reconstruction algorithms and establish the optimum parameters to be used in clinical studies. MATERIALS AND METHODS: We conducted a range of experiments using the National Electrical Manufacturers Association image quality phantom filled with a 4 : 1 signal-to-background ratio. We scanned the phantom using the GE Discovery 690 PET/CT scanner. We varied iteration number and Gaussian filtration. Results were compared for OSEM, OSEM+TOF and OSEM+TOF+PSF reconstructions. A sample of 15 whole-body fluorine-18-fluorodeoxyglucose were reconstructed with OSEM+TOF and OSEM+TOF+PSF using a selection of optimum reconstruction parameters determined in phantom studies. Clinicians qualitatively ranked their preferred images to choose optimum parameters. RESULTS: The addition of PSF improved signal-to-noise ratios (SNRs), contrast, hot contrast recovery coefficients and noise over OSEM and OSEM+TOF reconstruction algorithms. SNRs were the highest at two iterations and with 0 or 2 mm filters with OSEM+TOF+PSF reconstruction in all phantom studies. Clinicians generally favoured OSEM+TOF+PSF reconstruction with three iterations and a 2 mm filter. CONCLUSION: PSF reconstruction significantly improved image quality for both clinical and phantom studies. We recommended the optimum reconstruction parameters using three iterations, 24 subsets and a 2 mm filter, which improved SNRs by up to 28.8% for small lesions (P<0.05).

Is there a Role for Gallium-67 Citrate SPECT/CT, in Patients with Renal Impairment or Who are Renal Transplant Recipients, in Identifying and Localizing Suspected Infection?

To assess the added value of single-photon emission computed tomography/computed tomography (SPECT/CT) in patients with end-stage renal failure (ESRF) or renal transplant recipients in whom focal infection was suspected. Gallium-67 (Ga-67) citrate scintigrams of 18 patients (10 in ESRF and eight with renal transplants) were reviewed. Sites of abnormal uptake seen on the whole body and SPECT were noted. A SPECT/CT was also reviewed to see if additional information could be obtained. Imaging results were compared with the final diagnosis. Overall, 14 out of 18 (78%) patients had a proven cause to explain symptoms while four patients did not have a final cause identified. Infection was proven in the final diagnosis in 12 out of 14 (86%) patients. Of the 10 patients with ESRF, six had confirmed infection with the Ga-67 citrate study correctly identifying five out of six (83%) patients, and SPECT/CT providing additional information in four out of five (80%) patients. In the eight renal transplant recipients, six had a confirmed source of infection (all identified by the Ga-67 citrate study). SPECT/CT provided additional information in two out of six (33%) patients. Ga-67 citrate imaging had an overall sensitivity of 13/14 (93%), with one false negative. SPECT/CT provided an additional contribution in eight out of 18 (44%) patients by better defining the location/extent of infection and differentiating the physiological from the pathological uptake.

Localization of parathyroid disease with 'sequential multiphase and dual-tracer' technique and comparison with neck ultrasound.

OBJECTIVE: The aim of the study was to evaluate the accuracy of the sequential multiphase and dual-tracer (SMADT) technique utilizing technetium-99m pertechnetate (99mTcO4) and dynamic technetium-99m-2-methoxyisobutylisonitrile (99mTc-MIBI) with single-photon emission computed tomography/computed tomography (SPECT/CT) for localization of hyperfunctioning parathyroid tissue and compare the results with ultrasound (US). MATERIALS AND METHODS: Sixty-four patients with hyperparathyroidism were scanned over 4 years. For the SMADT technique, 80 MBq 99mTcO4 was injected with dynamic thyroid image acquisition started at 20 min, followed by 900 MBq 99mTc-MIBI injection at 30 min; the dynamic imaging continued for 50 min. SPECT was acquired at 60 min, with SPECT/CT of the neck at 3 h. Subsequent subtraction and statistical difference analyses were performed. Neck US was carried out within 3 months. Findings for each parathyroid gland and thyroid were classified as positive or negative. The patients underwent surgical resection of parathyroid tissue on the basis of imaging results. SMADT and US findings were correlated with histology as the gold standard. RESULTS: Eighty-six histological samples were resected. The sensitivity of SMADT for localization to individual glands was 70.6% [95% confidence interval (CI)=58.1-80.7%] and that for neck US was 60.3% (95% CI=47.7-71.8%, P=0.26). Specificity was 94.4% (95% CI=70.6-99.7%) for SMADT and 72.2% (95% CI=46.4-89.2%) for neck US (P=0.13). Sensitivities in multigland disease were 63.6% (95% CI=31.6-87.6%) for SMADT and 36.4% (95% CI=12.4-68.4%) for US (P=0.37) and in nodular thyroid disease were 83.8% (95% CI=67.3-93.2%) and 66.7% (95% CI=48.9-80.9%), respectively (P=0.07). CONCLUSION: SMADT results in better localization of varying parathyroid pathologies and complements the role of US in patients with multigland disease and nodular thyroid.

Single-photon emission computed tomography-computed tomography in imaging infection.

This review focuses on the current evidence available on the use of single-photon emission computed tomography-computed tomography (SPECT-CT) in infection imaging. The single-photon functional agents commonly used to image infection include In-111-labelled or Tc-99m-labelled leucocytes, Ga-67 citrate, Tc-99m-biphosphonates and radiolabelled antigranulocyte antibodies. Although many of these agents have been available for a long time, the development of hybrid SPECT-CT technology has led to a wider use of these agents. This review shows that the application of CT to single-photon imaging techniques for imaging infection can significantly improve the accuracy of the technique by increasing the specificity and better defining the location and extent of suspected disease. Hybrid fusion images also increase the confidence of the individual in reporting and seem to be applicable to a wide range of clinical situations. We believe that, overall, SPECT-CT, by providing a clearer assessment of whether infection is present and an accurate localization of the disease so that optimum treatment can be initiated, has a role in infection imaging.

Abnormal Tc99m sulesomab in Klippel-Trenaunay syndrome.

Tc-99m sulesomab is indicated in bone and joint infection, but reading of scans can be affected by pre-existing conditions. This case report describes a case of Klippel-Trenaunay syndrome (KTS) which results in vascular malformations of one or more limbs. Tc-99m sulesomab imaging demonstrated persistent blood pool activity up to 20 hours post injection. However, despite this, septic arthritis could be identified with confidence in the same limb.

FDG-PET/CT as a molecular biomarker in ovarian cancer.

In the clinical setting the vast majority of positron emission tomography (PET) procedures use the glucose analogue F-18 fluorodeoxyglucose (FDG) to visualize the increased glucose consumption of malignant lesions. Co-registered PET/CT has improved the diagnostic accuracy compared to either imaging procedure alone, particularly in ovarian cancer. FDG-PET/CT demonstrates primary malignant ovarian tumors; however, it is often unable to accurately differentiate between benign and malignant pelvic masses and to visualize borderline ovarian tumors. FDG-PET/CT has a suggested role for staging, by improving treatment planning in individual cases, but it is particularly helpful in the setting of disease recurrence when CA125 tumor marker levels are rising and conventional imaging (CT or MR) is inconclusive or negative. The aim of this review is to demonstrate the value of FDG-PET-CT in diagnosis and management of patients with ovarian malignancies, outlining its advantages and limitations.