Investigating the role of SPECT/CT in dynamic sentinel lymph node biopsy for penile cancers.

PURPOSE: Currently, most centres use 2-D planar lymphoscintigraphy when performing dynamic sentinel lymph node biopsy in penile cancer patients with clinically impalpable inguinal nodes. This study aimed to investigate the role of SPECT/CT following 2-D planar lymphoscintigraphy (dynamic and static) in the detection and localization of sentinel lymph nodes in the groin. METHODS: A qualitative (visual) review was performed on planar followed by SPECT/CT lymphoscintigraphy in 115 consecutive patients (age 28-86 years) who underwent injection of 99mTc-nanocolloid followed by immediate acquisition of dynamic (20 min) and early static scans (5 min) initially and further delayed static (5 min) images at 120 min followed by SPECT/CT imaging. The lymph nodes detected in each groin on planar lymphoscintigraphy and SPECT/CT were compared. RESULTS: A total of 440 and 467 nodes were identified on planar scintigraphy and SPECT/CT, respectively. Overall, SPECT/CT confirmed the findings of planar imaging in 28/115 cases (24%). In the remaining 87 cases (76%), gross discrepancies were observed between planar and SPECT/CT images. SPECT/CT identified 17 instances of skin contamination (16 patients, 13%) and 36 instances of in-transit lymphatic tract activity (24 patients, 20%) that had been interpreted as tracer-avid lymph nodes on planar imaging. In addition, SPECT/CT identified 53 tracer-avid nodes in 48 patients (42%) that were not visualized on planar imaging and led to reclassification of the drainage basins (pelvic/inguinal) of 27 tracer-avid nodes. CONCLUSIONS: The addition of SPECT/CT improved the rate of detection of true tracer-avid lymph nodes and delineated their precise (3-D) anatomic localization in drainage basins.

Distribution pattern of 68Ga-DOTATATE in disease-free patients.

PURPOSE: 68Ga-DOTA-DPhe1,Tyr3-octreotate (68Ga-DOTATATE) is a somatostatin analogue that shows high affinity for somatostatin receptor subtype 2 (sst2) and has been used for imaging neuroendocrine tumours. However, normal uptake patterns and potential pitfalls have not been described with this high-sensitivity radiotracer. The aim of this study was therefore to outline the normal distribution pattern of 68Ga-DOTATATE in disease-free patients, to provide standardized uptake values (SUVs) of various organs and to compare our results with the current knowledge on sst2 receptor expression in vitro. METHODS: 68Ga-DOTATATE PET/computed tomography was performed in 42 patients (15 men and 27 women). Approximately 145 MBq of tracer was injected intravenously and imaging was performed using a GE Discovery ST PET/computed tomography scanner. SUVs were calculated on the reconstructed images for various organs. RESULTS: 68Ga-DOTATATE uptake was noted in the sst2-expressing organs such as pituitary, thyroid, stomach wall, spleen, adrenals, kidneys, pancreas and prostate and in the liver and salivary glands, with excreted activity in the bowel and in the pelvicalyceal system of the kidneys and urinary bladder. The SUVs ranged from 0.1 to 48.8 in the organs considered. Potential pitfalls in interpreting the 68Ga-DOTATATE uptake in organs such as thyroid, pancreas lymph nodes and bowel were identified. CONCLUSION: This study shows the distribution pattern of 68Ga-DOTATATE outlines the range of SUVs for various organs in disease-free patients and identifies some of the potential pitfalls encountered during imaging.

Cardiovascular infection and inflammation.

Infectious and inflammatory processes, in particular those involving the cardiovascular system, are not a story of the past. New aggressive pathogens are responsible for difficult-to-treat infections. Present-day problems such as diabetes are associated with frequent and at times severe infectious processes, with high morbidity related to the disease or to available therapeutic options. Infections involving the heart or vessels pose clinical challenges in diagnosing and planning the most appropriate therapeutic strategy. Inflammatory processes are diagnosed more frequently today, acknowledged as pathologic conditions of high clinical significance, and much is invested in developing efficient therapeutic options. Nuclear medicine procedures are an important component of the evaluation armamentarium used in patients with suspected or confirmed infectious and inflammatory processes. Their role relies on the strength of noninvasive scintigraphic imaging tests that provide functional and metabolic information early during the course of the disease. Drawbacks of nuclear medicine procedures related to either the use of specific radiolabeled tracers or to their rather low resolution are overcome to a large extent during the last decade by the introduction of hybrid positron emission tomography/computed tomography and single-photon emission computed tomography/computed tomography imaging devices. Initial validated results regarding the role of nuclear medicine and of hybrid imaging using various radiotracers in the evaluation of cardiovascular infections and inflammatory processes are emerging over the last few years. They indicate the potentially important role of these modalities for early and precise diagnosis, in defining the whole extent of disease, for individualized treatment tailoring and for monitoring response to treatment. Attention needs to be given to match the appropriate imaging test and radiolabeled agent to the clinical question at hand. Nuclear medicine in general and hybrid imaging procedures in particular will redefine in future the diagnostic and therapeutic capabilities in patients with suspected or known infections and inflammations of the cardiovascular system.

High-grade mucoepidermoid carcinoma of the accessory parotid gland with distant metastases identified by 18F-FDG PET-CT.

We report a rare case of a metastatic mucoepidermoid carcinoma (MEC) arising from the accessory parotid gland in a 14-year-old male. In the pre-surgical assessment, the MR and CT showed no other abnormalities apart from the primary lesion. The lesion was excised and confirmed as a high-grade MEC. Four months later, he presented with a recurrence in his right temple. A (18)F-FDG PET-CT showed distal metastases in cervical nodes and lungs. In view of the findings and poor prognosis of the patient, surgical intervention and radiotherapy were not given and palliative measures offered. This case shows the potential of molecular imaging with (18)F-FDG PET-CT in these patients.

The impact of 18F-FDG PET/CT in patients with liver metastases.

PURPOSE: The aim of this study was to assess the performance of (18)F-fluorodeoxyglucose positron emission tomography/computed tomography ((18)F-FDG PET/CT) versus dedicated contrast-enhanced CT (CECT) in the detection of metastatic liver disease. METHODS: All patients that presented to our Institution with suspected metastatic liver disease who underwent (18)F-FDG PET/CT and CECT within 6 weeks of each other, were retrospectively analyzed, covering a 5-year period. One hundred and thirty-one patients (67 men, 64 women; mean age 62) were identified. Seventy-five had colorectal carcinoma and 56 had other malignancies. The performance of CECT and that of (18)F-FDG-PET/CT in detecting liver metastases were compared. The ability of each to detect local recurrence, extrahepatic metastases and to alter patient management was recorded. The final diagnosis was based on histology, clinical and radiological follow-up (mean 23 months). RESULTS: In detecting hepatic metastases, (18)F-FDG-PET/CT yielded 96% sensitivity and 75% specificity, whilst CECT showed 88% sensitivity and 25% specificity. (18)F-FDG-PET/CT and CECT were concordant in 102 out of 131 patients (78%). In the colorectal group (18)F-FDG-PET/CT showed 94% sensitivity and 75% specificity, whilst CECT had 91% sensitivity and 25% specificity. In the noncolorectal group (18)F-FDG-PET/CT showed 98% sensitivity and 75% specificity whilst CECT had 85% sensitivity and 25% specificity. Overall, (18)F-FDG-PET/CT altered patient management over CECT in 25% of patients. CECT did not alter patient management over (18)F-FDG-PET/CT alone in any patients. CONCLUSION: (18)F-FDG-PET/CT performed better in detecting metastatic liver disease than CECT in both colorectal and noncolorectal malignancies, and frequently altered patient management. The future role of CECT in these patients may need to be re-evaluated to avoid potentially unnecessary duplication of investigation where (18)F-PET/CT is readily available.

Frontal lobe dysfunction in sporadic hyperekplexia--case study and literature review.

Hyperekplexia (HE), or startle disease, is usually a familial disorder associated with mutations in the glycine receptor alpha1 subunit gene (GLRA1), characterised by exaggerated startle reactions to unexpected auditory, somaesthetic and visual stimuli. Non-familial cases may be idiopathic, or associated with pathology usually in the brainstem or rarely in the supratentorial compartment. The pathophysiological basis of HE is unclear. We report the case of a 40-year-old woman presenting with excessive startle response to unexpected stimuli and falls since the age of 16 years. There was no family history. She was initially diagnosed with epilepsy and started on phenytoin with no resolution of her symptoms. Clinical examination revealed hyperreflexia and an insecure broad-based gait but no other abnormalities. Routine comprehensive neuropsychological assessment revealed below average intelligence with signs of frontal lobe dysfunction. EEG showed non-specific abnormalities in the right frontal and central regions. A (99m)Tc-HMPAO SPET scan revealed hypoperfusion in the frontal (worse on the right) and temporal lobes and to a lesser extent in the basal ganglia. MRI was normal, as well as blood and CSF tests. No mutations were found in a genetic analysis of GLRA1. The patient improved partially with treatment by clonazepam. The localisation of the clinical and neuropsychological findings accord with the EEG and SPET scan abnormalities in our patient and corroborates previous reports. Appropriate neuropsychological testing and functional imaging enable more accurate delineation of the clinical phenotype of this rare disorder.

Myocardial perfusion scintigraphy: patients' perception of benefit and risk.

BACKGROUND AND AIM: Myocardial perfusion scintigraphy is a useful and safe investigation, which has now received approval by the National Institute of Clinical Excellence (NICE). However, there are common unpleasant side-effects to the drugs used and there is a risk from radiation. This study was performed to assess patients' perceptions of the benefits and risks of myocardial perfusion scintigraphy, and to determine whether the cardiac stress component influenced these perceptions. METHODS: Ninety patients attending our institution for thallium-201 myocardial perfusion study over a period of 2 months were interviewed with regard to their perception of the benefits of the study. Patients were interviewed prior to and following the stress study. RESULTS: On average, patients thought they had a good (three in four) chance of benefiting from myocardial perfusion imaging. Sixty per cent of patients were unaware that they were going to be exposed to ionizing radiation and over 80% were unaware of the side-effects. Two-thirds of the patients said they would undergo the test even if there was only a one in ten chance of benefiting. The majority of patients were uninfluenced by the stress component of the study. CONCLUSIONS: Many patients lack a knowledge of the risks of myocardial perfusion scintigraphy. Most patients would undergo myocardial perfusion studies even if they had a poor chance of benefit.

[(123)I]-FP-CIT-SPECT in the early diagnosis of PD presenting as exercise-induced dystonia.

Isolated foot dystonia following exercise is a rare manifestation of early PD. It may precede the onset of parkinsonism by years and can be clinically indistinguishable from familial exercise-induced dystonia. The authors present a patient with dystonic claudication where dopamine transporter SPECT using (123)I-FP-CIT allowed early diagnosis of PD and enabled effective symptomatic treatment with a dopamine agonist.