Diagnostic performance of prospective same-day 18F-FDG PET/MRI and 18F-FDG PET/CT in the staging and response assessment of lymphoma.

BACKGROUND: Accurate staging and response assessment are essential for prognosis and to guide treatment in patients with lymphoma. The aim of this study was to compare the diagnostic performance of FDG PET/MRI versus FDG PET/CT in adult patients with newly diagnosed Hodgkin and Non- Hodgkin lymphoma. METHODS: In this single centre study, 50 patients were prospectively recruited. FDG PET/MRI was performed after staging FDG PET/CT using a single injection of 18F-FDG. Patients were invited to complete same-day FDG PET/MRI with FDG PET/CT at interim and end of treatment response assessments. Performance was assessed using PET/CT as the reference standard for disease site identification, staging, response assessment with Deauville score and concordance in metabolic activity. RESULTS: Staging assessment showed perfect agreement (κ = 1.0, P = 0) between PET/MRI and PET/CT using Ann Arbor staging. There was excellent intermodality correlation with disease site identification at staging (κ = 0.976, P < 0.001) with FDG PET/MRI sensitivity of 96% (95% CI, 94-98%) and specificity of 100% (95% CI, 99-100%). There was good correlation of disease site identification at interim assessment (κ = 0.819, P < 0.001) and excellent correlation at end-of-treatment assessment (κ = 1.0, P < 0.001). Intermodality agreement for Deauville scores was good at interim assessment (κ = 0.808, P < 0.001) and excellent at end-of-treatment assessment (κ = 1.0, P = 0). There was good-excellent concordance in SUV max and mean between modalities across timepoints. Minimum calculated radiation patient effective dose saving was 54% between the two modalities per scan. CONCLUSION: With high concordance in disease site identification, staging and response assessment, PET/MR is a potentially viable alternative to PET/CT in lymphoma that minimises radiation exposure.

18F-FDG Superscan Caused by Extensive Bone Marrow Involvement in Hemophagocytic Lymphohistiocytosis.

An 82-year-old woman who initially presented with pulmonary infection had persistent pancytopenia, which presented a diagnostic dilemma requiring multiple bone marrow biopsies for eventual diagnosis of hemophagocytic lymphohistiocytosis. This case highlights the utility of FDG PET in (a) focusing attention on the bone marrow and reticuloendothelial system as the primary site of pathology and (b) excluding underlying malignancy and infection in this rare but potentially fatal hyperinflammatory condition caused by a highly stimulated but ineffective immune response.

Perineural spread of recurrent cutaneous melanoma along cervical nerves into the spinal cord.

Perineural spread of malignant melanoma is rare but increasingly recognized as a potential mechanism of metastasis particularly in desmoplastic melanoma, which has neurotropic characteristics. In the head and neck, this form of melanoma spread affecting cranial nerves has been described; however, to date, only one case of melanoma spreading to the brachial plexus has ever been reported. We present a case of cutaneous melanoma recurrence below the right jaw with perineural spread along the C3 and C4 nerves into the spinal cord, something which has not been documented previously in the literature.

Concordance of 18F-FDG PET Uptake in Tumor and Normal Tissues on PET/MRI and PET/CT.

AIM: The aim of this study was to assess the concordance of PET measurements of F-FDG uptake in tumor and normal tissues obtained on Australia's first clinical PET/MRI scanner in comparison to PET/CT, with comparison against published data. METHODS: One hundred subjects were prospectively recruited from an unselected, heterogeneous group of cancer patients to undergo F-FDG PET/CT and PET/MRI on the same day. SUVs of physiological regions and tumor tissues obtained by PET/MRI and PET/CT were compared and benchmarked against existing published data. Physiological activity was measured in the thoracic aorta and right lobe of the liver. Tumor SUVs were analyzed by cancer type, body region, and a combined group of all lesions. RESULTS: There was an excellent correlation between SUV measurements in tumor lesions obtained by PET/MRI and PET/CT, across all body regions and in all tumor types studied. There was a less robust correlation for SUVs measured in areas of physiological activity, but the level of agreement still fell within 2 SDs of mean. Data from this study showed comparable or smaller systemic biases and narrower confidence limits than existing studies in the literature comparing SUVs from PET/MRI and PET/CT. CONCLUSIONS: F-FDG PET/MRI appears promising as an adjunct or alternative to PET/CT for quantitative evaluation in oncology, independent of body region and tumor type, across a wide range of SUVs.

Cardiac Amyloid Imaging with 18F-Florbetaben PET: A Pilot Study.

Our aim was to determine the feasibility of 18F-florbetaben PET in diagnosing cardiac amyloidosis. METHODS: 18F-florbetaben PET was performed on 14 patients: 5 amyloid light chain, 5 amyloid transthyretin, and 4 control with hypertensive heart disease. Qualitative and quantitative assessments of 18F-florbetaben activity were performed using the SUVmean of the left ventricular myocardium and blood pool and calculation of target-to-background SUV ratio. Myocardial 18F-forbetaben retention was also calculated as the percentage mean myocardial SUV change between 0 and 5 min and 15 and 20 min after radiotracer injection. Global left ventricular longitudinal and right ventricular free wall longitudinal strain were calculated using 2-dimensional speckle-tracking echocardiography. RESULTS: Target-to-background SUV ratio and percentage myocardial 18F-forbetaben retention were higher in amyloid patients than in hypertensive controls. A cutoff of 40% was able to differentiate between cardiac amyloid patients and hypertensive controls. Percentage myocardial 18F-forbetaben retention was an independent determinant of both global left ventricular longitudinal and right ventricular free wall longitudinal strain via an inverse curve relationship. CONCLUSION: 18F-florbetaben PET imaging can accurately identify and differentiate between cardiac amyloidosis and hypertensive heart disease. Percentage myocardial 18F-florbetaben retention was an independent determinant of myocardial dysfunction in cardiac amyloidosis.

Gallium-68 PSMA uptake in adrenal adenoma.

Gallium-68 (Ga-68) labelled prostate-specific membrane antigen (PSMA) imaging by positron emission tomography (PET) has emerged as a promising tool for staging of prostate cancer and restaging of disease in recurrence or biochemical failure after definitive treatment of prostate cancer. Ga-68 PSMA PET produces high target-to-background images of prostate cancer and its metastases which are reflective of the significant overexpression of PSMA in these cells and greatly facilitates tumour detection. However, relatively little is known about the PSMA expression of benign neoplasms and non-prostate epithelial malignancies. This is a case report of PSMA uptake in an adrenal adenoma incidentally discovered on PET performed for restaging of biochemically suspected prostate cancer recurrence. With the increasing use of PSMA PET in the management of prostate cancer - and the not infrequent occurrence of adrenal adenomas - the appearance of low- to moderate-grade PSMA uptake in adrenal adenomas should be one with which reporting clinicians are familiar.

Bilateral cryptorchidism mimicking external iliac lymphadenopathy in a patient with leg melanoma: role of FDG-PET and ultrasound in management.

Cryptorchidism is the most common congenital anomaly present at birth in males. Spontaneous testicular descent occurs in the majority of patients, typically before 6 months of age. Radiology plays an important role, predominantly in the assessment of the nonpalpable testis, with ultrasound being the most commonly employed modality. Magnetic resonance imaging is however the most accurate modality for the assessment of the nonpalpable testis, particularly with the use of fat suppressed T2 and diffusion weighted sequences. While traditionally treated in infancy, the untreated or occult form can radiologically be mistaken for lymphadenopathy. Fluorodeoxyglucose (FDG) positron emission tomography can play an important role in differentiating cryptorchidism from lymphadenopathy, most commonly in patients with known malignancy, although FDG uptake can be variable. We present a case of bilateral cryptorchidism in an adult male which masqueraded as lymphadenopathy in a patient with lower limb melanoma.

The 'double pituitary hot spot' sign of skull base meningioma on gallium-68-labelled somatostatin analogue PET.

Gallium-68 ((68) Ga)-labelled somatostatin analogue imaging by positron emission tomography (PET) is increasingly replacing single photon (such as (111) In-labelled octreotide) imaging in the detection and staging of carcinoid and other neuroendocrine tumours. Among other tissues, pituitary uptake of 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid-octreotate (DOTA-TATE) and other somatostatin analogues is physiological. DOTA-TATE also accumulates in meningiomas, which have a high density of somatostatin receptor expression. The combination of pituitary and skull base meningioma uptake results in a characteristic 'double hot spot' appearance, which indicates the presence of a meningioma. This is a case of a middle-aged woman who underwent (68) Ga-DOTA-TATE PET for confirmation and staging of clinically suspected carcinoid tumour, in whom a skull base meningioma was incidentally discovered. With the increasing use of PET in the management of neuroendocrine tumours - and the not infrequent occurrence of meningiomas - the appearance of meningiomas on somatostatin analogue imaging should be one with which reporting clinicians are familiar.

Predicting tumour response.

Response prediction is an important emerging concept in oncologic imaging, with tailored, individualized treatment regimens increasingly becoming the standard of care. This review aims to define tumour response and illustrate the ways in which imaging techniques can demonstrate tumour biological characteristics that provide information on the likely benefit to be received by treatment. Two imaging approaches are described: identification of therapeutic targets and depiction of the treatment-resistant phenotype. The former approach is exemplified by the use of radionuclide imaging to confirm target expression before radionuclide therapy but with angiogenesis imaging and imaging correlates for genetic response predictors also demonstrating potential utility. Techniques to assess the treatment-resistant phenotype include demonstration of hypoperfusion with dynamic contrast-enhanced computed tomography and magnetic resonance imaging (MRI), depiction of necrosis with diffusion-weighted MRI, imaging of hypoxia and tumour adaption to hypoxia, and 99mTc-MIBI imaging of P-glycoprotein mediated drug resistance. To date, introduction of these techniques into clinical practice has often been constrained by inadequate cross-validation of predictive criteria and lack of verification against appropriate response end points such as survival. With further refinement, imaging predictors of response could play an important role in oncology, contributing to individualization of therapy based on the specific tumour phenotype. This ability to predict tumour response will have implications for improving efficacy of treatment, cost-effectiveness and omission of futile therapy.

Multidetector spiral CT renal angiography in the diagnosis of giant renal artery aneurysms.

A case of giant renal artery aneurysm in a 63-year-old man is presented. Renal artery aneurysms are rare (incidence of <1%) and this case is one of the largest giant renal artery aneurysms recorded in the literature. This case also demonstrates the value of multidetector spiral CT renal angiography (CTA) in the diagnosis, planning and treatment of renal aneurysms.

Helical CT in the diagnosis of acute lower gastrointestinal haemorrhage.

INTRODUCTION: A pilot study to evaluate helical computer tomography (CT) as a diagnostic tool for acute lower gastrointestinal tract (GIT) bleeding. CT was compared to conventional angiography (CA) and colonoscopy for the diagnosis and detection of bleeding site in suspected cases of acute lower GIT bleeding. METHODS: Seven patients presenting with acute lower GIT bleeding, between June and November 2002, underwent CT examinations. All of these seven patients underwent CA following CT. Emergency colonoscopies were performed on five patients investigated with both CT and CA. Median delay from the most recent episode of hematochezia to CT was two and a half hours, to CA was 3h, and to colonoscopy was 4h. None of the patients underwent nuclear medicine (NM) bleeding studies. RESULTS: Haemoglobin drop in all patients was greater than 15 g/L in the first 24h of presentation. The mean age was 68.86 years (range, 49-83 years). Comparing CT and CA, there were four concordant and three discordant results. Both modalities had concordant findings of two active bleeding sites, one non-bleeding rectal tumour, and one negative case result. In three patients, the source of bleeding was found on CT whereas CA was negative. Emergency colonoscopies performed in all of these three patients confirmed blood in the colon/ileum. CONCLUSION: Early experience suggests that CT is a safe, convenient and accurate diagnostic tool for acute lower GIT haemorrhage. It raises questions regarding the sensitivity of CA. A new management algorithm for acute lower GIT haemorrhage using CT as the pre-CA screening tool is being proposed based on the preliminary findings. Positive CT will allow directed therapeutic angiography, while negative CT will triage patients into alternative management pathways.

Impact of viral hepatitis co-infection on response to antiretroviral therapy and HIV disease progression in the HIV-NAT cohort.

OBJECTIVE: To examine the impact of viral hepatitis co-infection on HIV disease outcomes following commencement of combination antiretroviral therapy in a developing country setting. METHODS: HIV RNA suppression, CD4 cell count recovery, and HIV disease progression were examined within a cohort of Thai HIV-infected patients enrolled in eight HIV-NAT randomized controlled trials of antiretroviral therapy (n = 692). Hepatitis B virus (HBV) and hepatitis C virus (HCV) testing was performed on stored serum. RESULTS: Mean age was 32.3 years, 52% were male, 11% had CDC category C HIV disease at baseline, and 22% had received prior antiretroviral therapy. Prevalence of HBV, HCV and HBV/HCV co-infection was 8.7, 7.2 and 0.4%, respectively. Median HIV RNA reductions (log10 copies/ml) were approximately 1.5 for HIV, HIV-HBV, HIV-HCV subgroups from week 4 up to week 48. Mean increases in CD4 cell count were significantly lower among HIV-HBV and HIV-HCV subgroups at week 4 (HIV, 62 x 10(6) cells/l; HIV-HBV, 29 x 10(6) cells/l; HIV-HCV, 33 x 10(6) cells/l), however, by week 48 CD4 cell increases were similar (HIV, 115 x 10(6) cells/l; HIV-HBV, 113 x 10(6) cells/l; HIV-HCV, 97 x 10(6) cells/l). Cox regression analyses showed that HIV-HBV or HIV-HCV co-infection were not associated with a CD4 cell count increase of 100 x 10(6) cells/l over 48 weeks. Estimated progression to AIDS event or death at week 48 was 3.3% (95% confidence interval, 2.0-5.1%) for HIV, 6.7% (2.5-14.6%) for HIV-HBV, and 8.0% (2.2-20.5%) for HIV-HCV subgroups (P > 0.05). CONCLUSIONS: An early delayed CD4 count recovery among HIV/viral hepatitis co-infected patients was not sustained, and was not associated with increased HIV disease progression.

Risk of severe hepatotoxicity associated with antiretroviral therapy in the HIV-NAT Cohort, Thailand, 1996-2001.

OBJECTIVE: To examine rates and predictors of severe hepatotoxicity with combination antiretroviral therapy in a developing country setting: the eight HIV-NAT randomized controlled trials in Thailand. METHODS: All patients (n = 692) received at least two nucleoside reverse transcriptase inhibitors; 215 also received a non-nucleoside reverse transcriptase inhibitor (NNRTI) and 135 also received a protease inhibitor. Severe hepatotoxicity was defined as an increase in alanine aminotransferase (ALT) level to five times the upper limit of normal and an increase of at least 100 U/l from baseline. Liver function tests were available at baseline and weeks 4, 8, 12, 24, 36 and 48. Hepatitis B virus (HBV) and hepatitis C virus (HCV) testing was performed on stored serum. RESULTS: Mean age was 32.3 years; 52% were male, 11% had Centers for Disease Control and Prevention category C HIV disease at baseline, and 22% had received prior antiretroviral therapy. Prevalence of HBV, HCV and HBV/HCV coinfection was 8.7%, 7.2%, and 0.4%, respectively. Incidence of severe hepatotoxicity was 6.1/100 person-years [95% confidence interval (CI), 4.3-8.3/100]. In multivariate analysis, predictors of severe hepatotoxicity were HBV or HCV coinfection, and NNRTI-containing therapy. Incidence of severe hepatotoxicity was particularly high among patients receiving nevaripine (18.5/100 person-years; 95% CI, 11.6-27.8) and nevirapine/efavirenz (44.4/100 person-years; 95% CI, 12.1-113.7). CONCLUSIONS: Incidence and risk factors for severe hepatotoxicity appear similar among these Thai patients to those in other racial groups. Development of standardized antiretroviral therapy regimens for developing country settings should consider potential toxicity and capabilities for monitoring of toxicity.