Case Report of a Child after Hematopoietic Cell Transplantation with Acute Aspergillus Tracheobronchitis as a Cause for Respiratory Failure.

Rapid respiratory failure due to invasive mycosis of the airways is an uncommon presentation of Aspergillus infection, even in immunocompromised patients, and very few pediatric cases have been reported. Patients with Aspergillus tracheobronchitis present with nonspecific symptoms, and radiologic studies are often noninformative, leading to a delay in diagnosis. Prompt initiation of adequate antifungal therapies is of utmost importance to improve outcome. We report the case of a 9-year-old girl with chronic myelogenous leukemia who developed respiratory distress 41 days after hematopoietic cell transplantation and rapidly deteriorated despite multiple interventions and treatment modalities.

Parathyroid Imaging with Simultaneous Acquisition of 99mTc-Sestamibi and 123I: The Relative Merits of Pinhole Collimation and SPECT/CT.

UNLABELLED: The objective of this study was to determine the relative utility of 3 state-of-the-art parathyroid imaging protocols: single-time-point simultaneous acquisition of (99m)Tc-sestamibi and (123)I images with pinhole collimation in the anterior and bilateral anterior oblique projections, single-time-point simultaneous acquisition of (99m)Tc-sestamibi and (123)I images with SPECT/CT, and the combination of the first and second protocols. METHODS: Fifty-nine patients with surgical proof of parathyroid adenomas were evaluated retrospectively. All 3 protocols included perfectly coregistered subtraction images created by subtracting the (123)I images from the (99m)Tc-sestamibi images, plus an anterior parallel-hole collimator image of the neck and upper chest. The pinhole protocol was performed first, followed by the SPECT/CT protocol. Three image sets were derived from each study in each patient according to the above protocols. Two experienced observers recorded the size, location, and degree of certainty of any identified lesion. RESULTS: The 59 patients had 61 adenomas. For the 2 observers combined, the localization success rate was 88% for the pinhole protocol, 69% for the SPECT/CT protocol, and 81% for the combined protocol. The pinhole protocol detected more adenomas than the SPECT/CT protocol and missed fewer adenomas than either the SPECT/CT protocol or the combined pinhole and SPECT/CT protocol (P < 0.01). The 2 protocols that included SPECT/CT provided superior anatomic information relative to the location and size of the parathyroid adenomas. CONCLUSION: The pinhole protocol localized significantly more adenomas than the SPECT/CT protocol. However, the protocols that included SPECT/CT provided more anatomic information than pinhole imaging alone.

Anti-CTLA4 antibody therapy related complications on FDG PET/CT.

Anti-cytotoxic T-lymphocyte antigen-4 monoclonal antibody therapy is a new class of drug which has demonstrated increased overall survival in patients with metastatic melanoma. Anti-CTLA-4 antibody therapy inhibits the CTLA-4 inhibitory signal, thereby enhancing the anti-tumor response of the cytotoxic T lymphocytes. This response can lead to a variety of immune-related adverse events. Many of these events are present on follow-up PET/CT examinations performed to assess response to therapy. It is important for the interpreting physician to be aware of the findings on PET/CT to avoid diagnosing adverse events as progressive disease and to alert clinicians regarding these complications.

SPECT/CT of metastatic struma ovarii.

A 41-year-old woman presented with multiple right lower quadrant masses which were removed and consistent with metastatic follicular thyroid cancer. Thyroidectomy revealed no primary malignancy and evaluation of her ovaries was positive for struma ovarii. The patient was diagnosed with metastatic struma ovarii stage IV. Nine days following the patient's second therapy with I for recurrent disease, planar and SPECT/CT imaging demonstrated multiple I avid peritoneal nodules. At least one of them, located along the medial margin of the spleen, would have been difficult to diagnose without hybrid SPECT/CT imaging.

99mTc-mercaptoacetyltriglycine camera-based measurement of renal clearance: should the result be normalized for body surface area?

UNLABELLED: Testing the rate of creatinine clearance by measuring the level of creatinine in the blood and in a 24-h urine collection is a common method of evaluating renal function. The result is routinely normalized for body surface area (BSA). Alternatively, renal clearance can be measured by (99m)Tc-mercaptoacetyltriglycine (MAG3) renal imaging without the need for urine collection. Frequently, the (99m)Tc-MAG3 camera-based result is also normalized for BSA. METHODS: I evaluated the need for BSA normalization of renal clearance measurements in (99m)Tc-MAG3 imaging studies from both a conceptual and a mathematic point of view. Both approaches involved analyzing the effect of patient size, that is, BSA, on the factors blood volume, renal blood flow, and amount of test substance present in the blood in the creatinine clearance method compared with the (99m)Tc-MAG3 camera-based method. RESULTS: Both the conceptual and the mathematic analyses were consistent with a significant difference between the creatinine and (99m)Tc-MAG3 approaches to measuring renal clearance. Larger patients have larger kidneys, greater renal blood flow, higher renal clearances, larger blood volumes, more muscle mass, and higher BSAs than smaller patients. However, the concentration of creatinine in the blood of patients of any size with normal renal function is similar because the amount of creatinine released into the blood varies with patient muscle mass, which varies with blood volume. Because normalization for BSA is needed for creatinine clearance, a single reference range can be used for all patients. In the case of measurement of renal clearance with (99m)Tc-MAG3 imaging (assuming a constant dose), the concentration of tracer in the blood will vary inversely with patient size because blood volume varies with patient size. Thus, as patient size increases, the blood concentration of tracer will go down and compensate for the increase in renal blood flow and renal clearance, and conversely. Consequently, the (99m)Tc-MAG3 renal imaging study is self-correcting for BSA and no additional correction is needed. CONCLUSION: A conceptual and mathematic analysis suggests that, although normalization for BSA is necessary in the measurement of renal clearance by the standard creatinine clearance test, such normalization is inappropriate in the (99m)Tc-MAG3 camera-based imaging study because the (99m)Tc-MAG3 method is inherently self-normalizing for BSA.

Parathyroid imaging: the importance of pinhole collimation with both single- and dual-tracer acquisition.

UNLABELLED: Our objective was to rigorously compare pinhole and parallel-hole collimation in an intrapatient, intrastudy design in 2 parathyroid imaging protocols: the first was dual-phase (99m)Tc-sestamibi imaging, and the second was dual-phase (99m)Tc-sestamibi plus dual-tracer ((99m)Tc-sestamibi and (123)I) simultaneous-acquisition subtraction imaging. METHODS: Thirty-three patients with 37 surgically proven nonectopic parathyroid adenomas were evaluated. Anterior pinhole and parallel-hole images of the neck were available for (99m)Tc-sestamibi at 15 min and 3 h, and for simultaneously acquired (99m)Tc-sestamibi and (123)I subtraction at 15 min, all from a single study. The images were modified so that all had a square border and so that the thyroid filled approximately three quarters of the image. The images were evaluated by 2 experienced nuclear medicine physicians who did not know the surgical results or whether the images were acquired with pinhole or parallel-hole collimation. The observers indicated the location of any identified adenoma and graded the certainty of diagnosis on a 3-point scale. RESULTS: The localization success rate for the 2 observers combined for the single-tracer dual-phase images was 66.2% with pinhole collimation and 43.2% with parallel-hole collimation (P < 0.0001). The localization success rate with the addition of the dual-tracer simultaneous-acquisition subtraction image was 83.8% with pinhole collimation and 62.2% with parallel-hole collimation (P = 0.0018). In addition, the degree of certainty of localization was greater with pinhole collimation with both imaging protocols (P < 0.001 in both cases). CONCLUSION: In the anterior projection, pinhole collimation is superior to parallel-hole collimation for parathyroid imaging with either dual-phase (99m)Tc-sestamibi or dual-phase (99m)Tc-sestamibi plus dual-tracer ((99m)Tc-sestamibi and (123)I) simultaneous-acquisition subtraction.

PET/CT imaging of age- and task-associated differences in muscle activity during fatiguing contractions.

The study compared positron emission tomography/computed tomography (PET/CT) of [(18)F]-2-fluoro-2-deoxy-D-glucose ([(18)F]-FDG) uptake by skeletal muscles and the amount of muscle activity as indicated by surface electromyographic (EMG) recordings when young and old men performed fatiguing isometric contractions that required either force or position control. EMG signals were recorded from thigh muscles of six young men (26 ± 6 yr) and six old men (77 ± 6 yr) during fatiguing contractions with the knee extensors. PET/CT scans were performed immediately after task failure. Glucose uptake in 24 leg muscles, quantified as standardized uptake values, was greater for the old men after the force task and differed across tasks for the young men (force, 0.64 ± 0.3 g/ml; position, 0.73 ± 0.3 g/ml), but not the old men (force, 0.84 ± 0.3 g/ml; position, 0.79 ± 0.26 g/ml) (age × task interaction; P < 0.001). In contrast, the rate of increase in EMG amplitude for the agonist muscles was greater for the young men during the two contractions and there was no difference for either group of subjects in the rate of increase in EMG amplitude across the two tasks. The imaging estimates of glucose uptake indicated age- and task-dependent differences in the spatial distribution of [(18)F]-FDG uptake by skeletal muscles during fatiguing contractions. The findings demonstrate that PET/CT imaging of [(18)F]-FDG uptake, but not surface EMG recordings, detected the modulation of muscle activity across the fatiguing tasks by the young men but not the old men.

Parathyroid imaging: the importance of dual-radiopharmaceutical simultaneous acquisition with 99mTc-sestamibi and 123I.

UNLABELLED: Our objective was to compare the accuracy of 3 imaging protocols for the detection of parathyroid adenomas: single-tracer, dual-phase imaging with (99m)Tc-sestamibi; dual-tracer, single-phase imaging with simultaneous acquisition of (99m)Tc-sestamibi and (123)I images; and dual-tracer, dual-phase imaging with simultaneous acquisition of (99m)Tc-sestamibi and (123)I images. MATERIALS: Thirty-seven patients with surgical proof of parathyroid adenomas were evaluated. Three different protocols were derived from a single study in each patient, resulting in an intrapatient intrastudy comparison. The first derived protocol was the conventional dual-phase protocol with (99m)Tc-sestamibi consisting of anterior and anterior-oblique pinhole images of the neck at 15 min and 3 h plus parallel-hole images of the neck and upper chest at both imaging times. The second derived protocol was a dual-tracer, single-phase protocol consisting of administration of (123)I followed 2 h later by (99m)Tc-sestamibi. Fifteen minutes later, anterior and anterior oblique pinhole images of the (99m)Tc-sestamibi and (123)I were acquired simultaneously, allowing generation of perfectly coregistered subtraction images. Parallel-hole images of the neck and upper chest were also obtained. The third protocol was the same as the second except that the same imaging protocol was repeated at 3 h. Two experienced nuclear medicine physicians indicated the location of any identified lesion and graded the certainty of diagnosis on a 3-point scale. RESULTS: Thirty-seven patients had 41 parathyroid adenomas. For the 2 observers combined, the localization success rate was 66% for the single-tracer, dual-phase protocol; 94% for the dual-tracer, single-phase protocol; and 90% for the dual-phase, dual-tracer protocol. Both dual-tracer protocols were significantly more accurate than the single-tracer protocol (P < 0.01); there was no significant difference between the 2 dual-tracer protocols. In addition, the degree of certainty of localization was greater with the 2 dual-tracer protocols than the single-tracer protocol (P < 0.001). CONCLUSION: A dual-tracer, single-phase parathyroid imaging protocol consisting of simultaneous acquisition of (99m)Tc-sestamibi and (123)I images with pinhole collimation at 15 min and perfectly coregistered subtraction results in a higher degree of accuracy and a greater degree of diagnostic certainty than the commonly used single-tracer, dual-phase protocol of imaging (99m)Tc-sestamibi alone at 15 min and 3 h. The addition of delayed imaging to the dual-tracer protocol did not improve results.

The gastric emptying study with oatmeal: reference range and reproducibility as a function of age and sex.

UNLABELLED: This study evaluated the reference range and reproducibility of the gastric emptying study with oatmeal as a function of age and sex. METHODS: Twenty-four healthy subjects, 12 men and 12 women, categorized into 3 age groups, 20-40, 40-60, and 60-80 y, were studied twice, 1 d apart, with instant oatmeal labeled with (99m)Tc-sulfur colloid. Imaging was performed in the upright position using the left anterior oblique (LAO), right posterior oblique (RPO), anterior, and posterior projections. One-minute digital images acquired every 15 min for 60 min were used to calculate a simple half-time of emptying. RESULTS: A strong correlation was found among half-times of gastric emptying calculated from the anterior projection, LAO projection, anterior-posterior geometric mean, and LAO-RPO geometric mean (P < 0.01). A significant inverse correlation was found between increasing age and decreasing half-time of emptying in men and women (P < 0.05). A reference range of 10-60 min is suggested for 20- to 40-y-old patients, 10-40 min for 40- to 60-y-olds, and 10-30 min for 60- to 80-y-olds. Half-times of emptying tended to be longer for women than for men (not statistically significant). There was a large variation between the first and second studies, with a trend toward decreasing variation with increasing age in both men and women. In repeated studies, a reference range of variation of up to 30 min is suggested for 20- to 40-y-old patients, up to 20 min for 40- to 60-y-olds, and up to 15 min for 60- to 80-y-olds. CONCLUSION: The reference range for half-time of gastric emptying with instant oatmeal decreases with increasing age in both men and women. Test-retest variation is relatively large and tends to decrease with increasing age in both men and women. Data from either the LAO projection or the anterior-posterior geometric mean are acceptable for calculating the half-time of gastric emptying.

Decreased perfusion in the lateral wall of the left ventricle in PET/CT studies with 13N-ammonia: evaluation in healthy adults.

UNLABELLED: This study evaluated the causes of the frequently observed decreased myocardial perfusion in the lateral wall of the left ventricle in PET/CT studies with (13)N-ammonia in healthy adults. METHODS: Thirty-two adults who were undergoing PET/CT of the heart with (13)N-ammonia as part of a study of the effects of posttraumatic stress disorder in American Indians were included. Participants who had evidence of heart disease by a physician-administered questionnaire or by pharmacologic stress during the myocardial perfusion study were excluded. The ratio of counts in the lateral wall relative to the septum at stress and rest were compared with the degree of misalignment between the PET and CT images at the left border of the heart and at the right hemidiaphragm. RESULTS: No participant had evidence of heart disease. For the left heart border, 41% of participants showed misalignment at rest and 62% showed misalignment at stress. For the right hemidiaphragm, 28% showed misalignment at rest and 53% showed misalignment at stress. Among all participants, the decrease in lateral wall counts relative to the septum correlated with the degree of misalignment of the PET and CT images at the left heart border at rest using both average (P = 0.01) and maximum (P < 0.01) counts per pixel and at stress using maximum counts per pixel (P = 0.02) but not average counts per pixel (P = 0.14). There was also a correlation between the degree of misalignment of the PET and CT images at the left heart border and at the right hemidiaphragm at stress (P = 0.01) but not at rest (P = 0.09). The decreased counts in the lateral wall relative to the septum and the misalignment of the PET and CT images at the left heart border and at the right hemidiaphragm were all greater at stress than at rest (all P < 0.05). In those participants who had no misalignment of the PET and CT images at the left heart border, there was still a residual decrease in relative counts in the lateral wall at both stress and rest, using both average and maximum counts (all P < 0.05). CONCLUSION: Relative decreased counts in the lateral wall of the heart in PET/CT studies with (13)N-ammonia are commonly seen in healthy adults. The decreased counts in the lateral wall appear to be caused by an attenuation artifact from misalignment at the left border of the heart between the PET and CT images, possibly related to differences in respiratory motion during acquisition of the PET and CT images. In addition, there was a small, but significant, decrease in relative counts in the lateral wall even in participants without misalignment at the left heart border or at the right hemidiaphragm.

The gastric emptying study: protocol design considerations.

UNLABELLED: This study evaluated the intrapatient correlation for gastric emptying times with instant oatmeal and scrambled egg meals. In addition, this study evaluated the degree of overlap between the stomach and the colon or jejunum in the anterior (AP) and left anterior oblique (LAO) projections in CT studies of the abdomen. METHODS: Fifteen patients were studied twice, 1 d apart, with instant oatmeal and scrambled egg meals, both of which were labeled with (99m)Tc-sulfur colloid. Imaging was performed in the upright position with the LAO projection. One-minute digital images acquired every 15 min were used to calculate a simple half-time of emptying. The correlation coefficient between the oatmeal and egg meals was calculated. In addition, the degree of overlap between the stomach and the colon or jejunum in the AP and LAO projections in 100 CT studies of the abdomen was categorized as none, mild (up to 25%), moderate (25%-50%), or marked (>50%). RESULTS: One pair of gastric emptying studies was eliminated as an outlier because the distribution of the meals in the stomach, as determined by imaging, was very different for the 2 studies. In the remaining 14 patients, the correlation coefficient for half-times of emptying for the oatmeal and egg meals was 0.77 (P < 0.01). The stomach overlapped the colon 74% of the time in the AP projection and 82% of the time in the LAO projection (P = not significant). The stomach overlapped the jejunum 77% of the time in the AP projection but only 52% of the time in the LAO projection (P < 0.05). CONCLUSION: The significant correlation between the instant oatmeal and scrambled egg gastric emptying times suggests that similar information is provided by the 2 meals. The frequent overlap of the stomach and the colon in both the AP and the LAO projections suggests that imaging at delayed times, such as 4 h, is likely to be problematic because of colonic activity within the stomach region of interest. In addition, the frequent overlap of the stomach and the jejunum has implications for calculation of the lag time; the less frequent overlap of the stomach and the jejunum in the LAO projection than in the AP projection may be an advantage for imaging in the LAO projection.

Intrapatient comparison of 2-deoxy-2-[F-18]fluoro-D-glucose with positron emissiontomography/computed tomography to Tc-99m fanolesomab (NeutroSpec) for localization of infection.

PURPOSE: This study evaluated the efficacy of 2-deoxy-2-[F-18]fluoro-D: -glucose (FDG) with positron emission tomography/computed tomography (PET/CT) in comparison with Tc-99m fanolesomab (NeutroSpec) for imaging infection. PROCEDURES: Twelve patients with possible infection were studied with both FDG-PET/CT and Tc-99m fanolesomab. One patient was studied twice for a total of 13 paired studies. The final determination of the presence or absence of infection and the site(s) of infection at the time of imaging was made by an infectious disease physician using culture results and other relevant information. The sensitivity, specificity, and accuracy were calculated for each imaging study on a per paired study basis and a per lesion basis. In addition, the quality of lesion depicted was compared between the two studies. RESULTS: Three patients were determined not to have infection. Ten paired studies, in nine patients, were determined to have one or more sites of infection: seven had one site and three had two sites. On a per paired study basis the sensitivity, specificity, and accuracy of FDG-PET/CT were all 100%; for Tc-99m fanolesomab these parameters were 30, 100, and 46%, respectively (P < 0.01 for sensitivity and accuracy). On a per site basis the results for FDG-PET/CT were all 100% and for Tc-99m fanolesomab they were 23, 100, and 38% (P < 0.01 for sensitivity and accuracy). In the three sites of infection shown by both studies, FDG-PET/CT was judged to be superior in spatial resolution and anatomic localization compared to Tc-99m fanolesomab in all three sites. CONCLUSION: FDG-PET/CT is superior to Tc-99m fanolesomab for detecting and localizing sites of infection.