Abdominal scintigraphy using99mTc-HMPAO-labelled leucocytes in patients with seronegative spondylarthropathies without clinical evidence of inflammatory bowel disease

Abdominal scintigraphy with technetium-99m hexamethylpropylene amine oxime (^99mTc-HMPAO)-labelled leucocytes is an excellent tool for evaluating disease extent and activity of intestinal lesions in patients with inflammatory bowel disease (IBD). In some cases of seronegative spondylarthropathies (SSp), IBD may remain subclinical. The aim of this study was to evaluate the presence of positive abdominal scintigraphy in patients with SSp and without clinical symptoms or signs of IBD. To this end we studied 32 patients with active SSp (European Spondylarthropathy Study Group 1991 criteria) without clinical evidence of IBD (eight had ankylosing spondylitis, four psoriatic arthritis, three reactive arthritis an 17 undifferentiated SSp) and 11 controls without SSp. All SSp and control patients received similar doses of non-steroidal anti-inflammatory drugs (NSAIDs). Abdominal scintigraphic images were obtained at 30 and 120 min after re-injection of^99mTc-HMPAO-labelled leucocytes. The^99mTc-HMPAO-labelled leucocyte scan was positive in 17 patients with SSp (53.1%) (six with ankylosing spondylitis, three with psoriatic arthritis, two with reactive arthritis and six with undifferentiated SSp). Fourteen patients scored from 2 to 4 on the intensity of uptake scale. The colon and terminal ileum were predominantly involved. Axial involvement was more frequent in patients with a positive scan than in patients with negative results (P<0.05) (64.7% vs 26.6%; odds ratio: 5). No control patient showed a positive scan. It is concluded that^99mTc-HMPAO-labelled leucocyte scan shows increased uptake among patients with SSp without evidence of IBD. These findings provide new evidence linking SSp with intestinal inflammation and suggest that in some cases a bowel-related process could contribute to the development of SSp. Longterm follow-up studies with more patients are necessary to evaluate the diagnostic and therapeutic implications of these results.     

Pethidine-augmented white cell scintigraphy in inflammatory bowel disease

Technetium-99m hexamethylpropylene amine oxime (^99mTc-HMPAO) white cell scintigraphy is invaluable for assessing the presence and extent of disease activity in patients with inflammatory bowel disease. Interpretation of images can be compromised by physiological excretion of tracer into the bowel via the biliary tree. This study assesses the effect of intravenous pethidine administered with the labelled white cells in an attempt to reduce the enterohepatic circulation of the tracer. Ninety-one subjects with proven or suspected inflammatory bowel disease were included in this study, all of whom underwent ^99mTc-HMPAO white cell scintigraphy. The control group of 50 subjects underwent the standard protocol for this study performed in our department. The other 41 subjects received an intravenous injection of 0.3 mg/kg of pethidine at the same time as re-injection of the labelled white cells. Images were graded using a five-point scale at both 1 and 2.5 h and categorised as positive, negative or non-diagnostic. Each scan was also assessed for the presence of a visible gall-bladder. The pethidine group had significantly fewer non-diagnostic scans than the control group (P=0.003), and significantly (P=0.001) more studies in which the gall-bladder was visualised. It is concluded that the use of pethidine appears to reduce biliary excretion of tracer during ^99mTc-HMPAO white cell scintigraphy. This may allow the delayed images, and early images with low-grade tracer uptake in the bowel, to be interpreted with greater confidence and thereby reduce the number of scans classified as non-diagnostic. Received 14 December 1999 and in revised form 16 February 2000     

Uptake of technetium-99m hexamethylpropylene amine oxime labelled white cells in lymph nodes involved in non-Hodgkin's lymphoma

Radiolabelled white cell scanning is widely used to detect the presence of infection. We present a case of non-Hodgkin's lymphoma manifesting with signs and symptoms suggestive of infection, in which a technetium-99m hexamethylpropylene amine oxime (^99mTc-HMPAO) white cell scan demonstrated high uptake in lymph nodes involved by lymphoma. Differential cell analysis showed preferential lymphocyte labelling. The classification and management of the disease were changed accordingly. Our findings suggest that a future role for^99mTc-HMPAO labelled white cells in the assessment of disease activity of lymphoma should be investigated.     

Technetium-99m hexamethylpropylene amine oxime labelled leucocyte scintigraphy in ulcerative colitis and Crohn's disease

Technetium-99m hexamethylpropylene amine oxime labelled leucocyte scintigraphy (LS) was performed on 45 occasions in 30 patients with ulcerative colitis and on 53 occasions in 34 patients with Crohn's disease. Serial images were taken following re-injection of the labelled leucocytes. The segmental extent of the inflammation and the grade of the leucocyte uptake were calculated, and compared with the laboratory results and colonoscopy findings. The sensitivity and specificity of LS proved higher in ulcerative colitis (87% and 93%) than in Crohn's disease (53% and 89% in cases with large intestine involvement, and 82% and 100% in cases with small intestine involvement). The activity of the process determined by LS correlates with the ₂ globulin level (r=0.47), fibrinogen level (r=0.50), fS iron level (r=–0.57), sedimentation (r=0.44), leucocyte count (r=0.38), platelet count (r=0.34) and Best index (r=0.31) in ulcerative colitis, but not in Crohn's disease. Correspondence to: M. Papós     

Evaluation of white cell scintigraphy using indium-111 and technetium-99m labelled leucocytes

Indium-111 oxine labelled leucocyte (¹¹¹In oxine leucocyte) scintigraphy is the test of choice in detecting occult infection and localising focal inflammation. ¹¹¹In oxine labelling is technically difficult and expensive and leucocyte labelling with technetium-99m stannous colloid (^99mTc Sn colloid) has been considered to be an alternative. Leucocytes from 40 cases referred for investigation of occult infection or localisation of inflammation were simultaneously labelled with ¹¹¹In oxine and ^99mTc Sn colloid with dual isotope acquisition performed at 1, 3 and 24 h. Twenty-four hour ^99mTc Sn colloid scans were corrected for ¹¹¹In downscatter. Each case was independently interpreted by two experienced observers. Twentyone patients demonstrated positive ¹¹¹In oxine leucocyte scans. Using ¹¹¹In oxine leucocyte scans as the gold standard, ^99mTc Sn colloid leucocyte scanning had an overall sensitivity of 86% and a specificity of 95%. Clinical follow-up verified that three patients had false negative ^99mTc Sn colloid leucocyte scans and one patient had a false positive. Further clinical evaluation of ^99mTc Sn colloid labelled leucocytes is required before they can become a reliable replacement for ¹¹¹In oxine leucocytes. Correspondence to: S. Boyd     

Scintigraphic evaluation of disease activity in rheumatoid arthritis: a comparison of technetium-99m human non-specific immunoglobulins,leucocytes and albumin nanocolloids

Technetium-99m-labelled, non-specific, polyclonal, human immunoglobulin G (^99mTc-hIG) has been used to quantify synovial inflammation in rheumatoid arthritis. A comparison was carried out between the scintigraphic results obtained with this tracer, ^99mTc-hexamethylpropylene amine oxime-labelled white blood cells (^99mTc-WBC) and ^99mTc-albumin nanocolloids (^99mTc-NC). Twenty patients affected by rheumatoid arthritis and suffering from clinically active synovitis were studied with ^99mTc-hIG. The number and sites of the involved joints had been previously assessed on the basis of the presence of pain and/or swelling. A radiological examination had already been carried out on all the joints. Two days after the ^99mTc-hIG scan, 10 patients (group 1) underwent ^99mTc-WBC scintigraphy and the other 10 (group 2) underwent a ^99mTc-NC scan. The results show that the results of ^99mTc-hIG and^99m Tc-NC scans are in agreement with clinical examinations in the majority of cases. However, a certain number of positive joint scans corresponding to negative clinical examinations was found. The numerical distribution of these results according to the radiological stages seems to show that^99m Tc-hIG is more useful than ^99mTc-NC in the initial phases of the disease. The ^99mTc-WBC scan was negative in a consistent percentage of the joints previously assessed as clinically and ^99mTc-hIG scan positive. Offprint requests to: M. Liberatore     

Intraindividual comparison of 99mTc-labelled anti-SSEA-1 antigranulocyte antibody and 99mTc-HMPAO labelled white blood cells for the imaging of infection

Technetium-99m labelled antigranulocyte antibodies are ready to use and are sensitive and specific in the diagnosis of infectious diseases. ^99mTc-SSEA antigranulocyte antibodies have a very high affinity constant (K _d 10^–12 M) for human neutrophils (PMNs), and excellent imaging qualities with high target/background ratios. The aim of this study was to compare the diagnostic accuracy of the ^99mTc-anti-SSEA-1 monoclonal antibody (Mab) with that of ^99mTc-hexamethylpropylene amine oxime (HMPAO)-labelled white blood cells (WBCs). To this end, 17 patients with 23 proven infectious foci were examined with 555 MBq ^99mTc-anti-SSEA-1 MAb and with 370 MBq ^99mTc-HMPAO labelled autologous leucocytes within a period of 7 days. All the infections were confirmed by culture, biopsy, surgery and follow-up. Whole-body images and planar spot views with the antibody were performed at 1-h, 4-h and 24-h post injection; the biodistribution of the antibody was quantified, absorbed radiation doses were calculated and the diagnostic results were compared with the ^99mTc-HMPAO WBC images. Human anti-mouse antibody (HAMA) evaluation was performed in all patients before and 3 months after antibody injection. Blood was drawn at different times after ^99mTc-anti-SSEA-1 MAb injection to determine the amount of granulocyte-associated radioactivity and to calculate recovery. ^99mTc-anti-SSEA-1 MAb scintigraphy detected all 23 lesions, while 21 were detected with ^99mTc-HMPAO WBC scan. In this small group of patients, the sensitivity and specificity of ^99mTc-anti-SSEA-1 MAb scintigraphy were 95% and 96% respectively, as compared with 91% and 82% respectively for ^99mTc-HMPAO WBC scan. An increasing uptake of the injected activity in the lesion at different time points was indicative of high affinity and of specific PMN binding.There was no HAMA formation. In four of five patients investigated, a transient mild leukopenia was found at 15 min p.i.. There was increased uptake of the antibody in liver and spleen and normal uptake in kidneys and bone marrow.The estimated radiation doses for the whole body and the red bone marrow were 1.1×10^–2 cGy/37 MBq and 5.3×10^–2 cGy/37 MBq, respectively. The activity associated to the PMNs in vivo was 33.5%, 30.6%, 21.3% and 9% at 5, 15, 30 and 45 min. post-injection, respectively. It is councluded that use of ^99mTc-anti-SSEA-1 antigranulocyte antibodies demonstrates promising results comparable to those obtained with ^99mTc-labelled autologous WBCs. The ^99mTc-labelled MAb is ready to use, has excellent image qualities and a high target/background ratio. Received 16 October and in revised form 17 December 1997     

Technetium-99m scintigraphy: more accurate assessment of ulcerative colitis with exametazime-labelled leucocytes than with antigranulocyte antibodies

To compare two technetium-99m scintigraphic techniques —^99mTc-labelled antibodies against granulocyte non-specific cross-reacting antigen-95 and^99mTc-exametazime labelled leucocytes in ulcerative colitis —23 consecutive patients undergoing colonoscopy were investigated in a prospective and randomized study. In each patient the two scans and colonoscopy and biopsy were performed within 10 days. Scans, endoscopy and histology were independently graded for degree of inflammation in eight different colorectal segments for each patient. Active inflammation in one or more segments was present on endoscopy in 22 patients and on histology in 17 patients. Twenty-two patients had increased uptake on the antibody scan and 21 patients on the exametazime scan. Twelve patients showed the same disease extent with both scan methods (total colitis,n=10; distal colitis,n=2). Compared with endoscopy, sensitivity for inflammation in individual segments was 0.51 for antibody scan and 0.87 for exametazime scan; specificity was 0.67 and 0.55, respectively. The predictive value for presence of inflammation was 0.66 for antibody scan and 0.72 for exametazime; the predictive value for absence of inflammation was 0.52 and 0.77, respectively. Segmental scan uptake of endoscopically or histologically visualized inflammation was consistently lower for antigranulocyte antibodies than for exametazime. It is concluded that in patients with active ulcerative colitis, inflammation is better visualized with^99mTc-exametazime labelled leucocytes than with^99mTc-labelled antigranulocyte antibodies. The antibody technique offers the advantage of in vivo labelling, but is less reliable than the exametazime method for imaging of colonic inflammation.     

Technetium-99m hexamethyl propylene amine oxine leucocytes in the assessment of disease activity in inflammatory bowel disease

The inflammatory activity in 108 bowel segments of 40 patients with suspected or known inflammatory bowel disease was assessed macroscopically by endoscopy, histology and technetium-99m hexamethyl propylene amine oxine (^99mTc-HMPAO) leucocytes using a numerical grading system (scores 0–3). A 4-h series of scintigrams showed a significant correlation with both histological and macroscopical assessment of disease activity (rho = 0.850, P<0.001 and rho = 0.773, P<0.001, respectively). Sensitivity, specificity and accuracy of scintigraphy in detecting active inflammatory segments were 85%, 92% and 89%, respectively. A normal scintigram did not completely exclude mild inflammatory activity, especially in the rectosigmoid area. ^99mTc-HMPAO leucocytes offer an accurate and non-invasive alternative for the assessment of disease activity in ulcerative colitis and Crohn's disease. Offprint requests to: E. Lantto     

Chronic osteomyelitis: diagnosis with tech netium-99m-d,l-hexamethylpropylene amine oxime labelled leucocytes

To evaluate the diagnostic value of technetium-99md,l-hexamethylpropylene amine oxime (HMPAO) labelled leucocytes in combination with a^99mTc-methylene diphosphonate (MDP) bone scan in the detection of chronic osteomyelitis, we retrospectively reviewed 55 patients. Prior to the^99mTc-d,I-HMPAO labelled leucocyte scan, all patients underwent a^99mTc-MDP bone scan. The correct diagnosis was confirmed by long-term clinical follow-up (n=29) or by bacteriological cultures (n=26). We found an overall sensitivity of 94%, a specificity of 91% and an accuracy of 92% for^99mTc-d,l-HMPAO labelled leucocyte scintigraphy in the diagnosis of chronic osteomyelitis. When the patients were divided into three groups according to the location of the infection, our study results showed a sensitivity and specificity for the central location (containing active bone marrow) of 94% and 100% respectively; for the peripheral location (hands and feet) both parameters were 100%, and for the middle location (all sites between the central and the peripheral location) the values were 92% and 81% respectively. Specificity and accuracy were significantly lower in the middle location than in the central and peripheral locations. The results of our study confirm that a^99mTc-d,l-HMPAO labelled leucocyte scan in combination with an^99mTc-MDP bone scan is a reliable way to diagnose chronic osteomyelitis, except for vertebral osteomyelitis.     

Imaging of bone infection with labelled white blood cells role of contemporaneous bone marrow imaging

The uptake of white blood cells (WBC) into normal bone marrow may lead to difficulty in detecting bone infection. Twenty-one patients in whom the WBC scan was equivocal or positive underwent a technetium 99m colloid scan to show the distribution of bone marrow. Six patients had a positive WBC scan, and in five of them a discordant colloid scan confirmed infection. However, in one the colloid scan was concordant, indicating that the WBC activity was not due to infection but the result of normal bone marrow uptake. Fifteen patients had an equivocal WBC scan. In 14, infection was excluded by a concordant scan, and 1 patient with a discordant scan was lost to follow-up. We conclude that the combination of a WBC scan and a colloid scan is an effective method to distinguish infection from normal bone marrow activity and, in particular, reduces the number of incorrect diagnoses of infection.     

Upregulation of granulocyte CD11b (CR 3) after labelling with technetium-99m hexamethylpropylene amine oxime

Today technetium-99m hexamethylpropylene amine oxime (^99mTc-HMPAO) is widely used for leucocyte scintigraphy, as^99mTc-HMPAO selectively labels granulocytes in mixed leucocyte suspensions. However, the influence of cell labelling on the expression of specific adhesion proteins has not been studied before. Therefore, we investigated five patients, four of whom had established Crohn's disease. We found that leucocyte labelling with^99mTc-HMPAO induces increased expression of the glucoprotein receptor CD11b on granulocytes, but it is not clear whether this upregulation affects the functional integrity of the granulocytes.     

Semi-quantitative assessment of cerebral blood flow with 99mTc-HMPAO SPET in type I diabetic patients with no clinical history of cerebrovascular disease

In 65 type I diabetic patients we prospectively evaluated brain perfusion by means of single-photon emission tomography after the injection of 740– 1110 MBq of technetium-99m hexamethylpropylene amine oxime. Thirty-five of the patients presented complications secondary to their diabetes. None showed CNS symptoms. A semiquantitative analysis was performed drawing 50 symmetrical regions of interest (ROIs) per patient. The relative contribution of each ROI to the total blood flow in each slice was compared with the relative contribution of the same ROI in a control group of ten healthy volunteers. Relative values of any ROI in the study group higher or lower than the mean ±2 SD in respect of the same ROI in the control group were considered abnormal. The results revealed hypoperfusion in 207 ROIs in the 65 patients with diabetes mellitus: of these ROIs, 113 were frontal, 10 frontotemporal, 20 temporal, 18 parietal, 11 occipital and 35 cerebellar. A total of 137 ROIs showed hyperperfusion: 17 frontal, 3 frontotemporal, 19 temporal, 18 parietal, 19 parieto-occipital, 29 occipital and 32 cerebellar. Out of 65 type I diabetic patients, 61 showed at least one hypoperfused ROI (P = 0.0064 vs. controls) and 25 showed more than three hypoperfused ROIs. None of the control subjects showed more than three hypoperfused regions (P<0.001). The results obtained demonstrate the existence of subclinical abnormalities of brain blood perfusion in patients with type I diabetes mellitus and no history of cerebrovascular disease, thereby allowing the initiation of intensive preventive measures. Received 16 July and in revised form 16 August 1997     

Comparison of simultaneous 99mTc-HMPAO and 111In oxine labelled white cell scans in the assessment of inflammatory bowel disease

Forty-seven patients, 29 with chronic inflammatory bowel disease (1131) and 18 with presumed irritable bowel syndrome, including one with uncomplicated diverticular disease, were studied with simultaneous technetium-99m hexamethylpropylene amine oxime and indium-111 oxine labelled leucocyte scans performed at 1, 3 and 24 h. Twenty-seven patients with IBD had active disease as judged by clinical and laboratory criteria and all of these had positive scans with both agents. No false positive studies were obtained. The 1-h ^99mTc-HMPAO WBC scans showed the same distribution to disease as the 3-h ¹¹¹-In WBC scans, with no difference in intensity (P < 0.92); they showed more extensive disease (P < 0.02) and more intense uptake (P < 0.001) than did the 1-h ¹¹¹-In scans. The 3-h ^99mTc-HMPAO WBC scans showed more extensive disease (P < 0.002), with greater intensity (P < 0.0005), than did the 3-h ¹¹¹In WBC scans. Physiological bowel activity on 3-h ^99mTc-HMPAO WBC scans was present in 12 patients but was faint and did not interfere with assessment of disease extent and activity. It is concluded that in terms of isotope availability, radiation dosimetry and image quality, ^99mTc-HMPAO is the agent of choice in detecting active IBD, with localization of disease possible at 1-h after re-injection and optimal resolution and definition of disease extent at 3 h. A negative scan reliably excludes active disease. Correspondence to: R.A. Allan     

The use of technetium-99m hexamethylpropylene amine oxime labelled white blood cells to detect subclinical inflammation of the heart after cardiopulmonary bypass in children with congenital heart disease

Ten children (6 boys and 4 girls, aged 1–9 years old) underwent operations with a cardiopulmonary bypass, and the technetium-99m hexamethylpropylene amine oxine (^99mTc-HMPAO) labelled white blood cell (WBC) heart scans were used to detect postoperative leukocyte infiltration in the hearts. The results showed that 80% (/810) of the cases had subclinical inflammation in the hearts (grading of WBC scans score 2), and a positive correlation (R = 0.77) was noted between the severity of the inflammation (grading of the WBC scans) and the duration of the cardiopulmonary bypass in the operations. Another control group (9 boys and 2 girls, aged 2–13 years old) underwent operations without a cardiopulmonary bypass, and subclinical inflammation of hearts was demonstrated in only 1 case (9%) by the ^99mTc-HMPAO labelled WBC scans (grading of WBC scans < score 2) after the operations. There was a significant difference (P < 0.001, by a Wilcoxon rank sum test) based upon the severity of the ischaemic heart damage in the two groups. In our preliminary conclusions, the ^99mTc-HMPAO labelled WBC heart scans may provide non-invasive and directly discernible evidence of subclinical inflammation in the heart due to a transient ischaemic state during a cardiopulmonary bypass, even if the clinical symptoms and signs of carditis are not apparent. Correspondence to: Chia-Hung Kao     

Postoperative assessment of cerebral blood flow in subarachnoid haemorrhage by means of99mTc-HMPAO tomography

Regional hypoperfusion is a very frequent complication of subarachnoid haemorrhage (SAH), being related to vasospasm in the majority of cases. Twenty-six patients who were admitted for SAH underwent follow-up with technetium-99m hexamethylpropylene amine oxime single photon emission tomography (SPECT) 3 and 8 days after surgery. Fifteen patients of these had one more examination 15 days after surgery. The degree of hypoperfusion was quantified using an index of asymmetry which allow the comparison of two symmetrical regions of interest (ROIs) on the transaxial slice which presented the greatest perfusion defect. Comparison of CT data, transcranial Doppler data and clinical signs with the perfusion as quantified by^99mTc-HMPAO SPECT indicates that a difference in counts of less than 10% between the two symmetrical ROIs is of no diagnostic value. Follow-up of the brain perfusion clearly shows that the most pronounced hypoperfusion was observed just after surgery, with progressive normalization at 8 and 15 days after surgery.^99mTc-HMPAO SPECT performed 8 days after surgery allows prediction of the clinical outcome. For these reasons,^99mTc-HMPAO SPECT, which is the only method for follow-up of cerebral perfusion in routine clinical practice, should be the first examination to be performed after surgery in patients with SAH.     

18FDG PET and acetazolamide-enhanced99mTc-HMPAO SPET in systemic lupus erythematosus

In systemic lupus erythematosus (SLE), brain and kidney are the most frequently affected organs. Measurements of cerebral blood flow and metabolism by means of positron emission tomography (PET) and single-photon emission tomography (SPET) can contribute to the diagnostic assessment of the involvement of the central nervous system (CNS) in SLE. Functional imaging has been proven to be more sensitive than morphological imaging (magnetic resonance imaging and computed tomography). In this report, we present the case of a 70-year-old female patient, suffering from SLE without symptoms of CNS involvement. In addition to a SPET study using technetium-99m hexamethylpropylene amine oxime (^99mTc-HMPAO) and a PET scan with fluorine-18 deoxyglucose (¹⁸FDG), a SPET study after acetazolamide injection was performed in order to assess the cerebral perfusion reserve. While the PET scan showed no major abnormalities, and the baseline SPET study revealed only minor changes, the acetazolamide-enhanced SPET study revealed a marked reduction of the cortical perfusion reserve, particularly in both frontal lobes. It is concluded that preclinical CNS involvement, mainly caused by pathological mechanisms involving the cerebral blood vessels, can be considered to exist in this patient with SLE.     

Scintigraphic findings on99mTc-MDP,99mTc-sestamibi and99mTc-HMPAO images in Gaucher's disease

Gaucher's disease is an autosomal recessive lysosomal storage disease characterized by the specific deficiency of glucocerebrosidase that leads to accumulation of insoluble glucocerebroside in the reticuloendothelial system, particularly the bone marrow, liver, spleen and lymph nodes. Direct scintigraphic visualization of lipid deposits in Gaucher's disease has recently been described, based on the use of the lipid-soluble xenon-133. We report here on the use of the lipophilic cat-ionic complex technetium-99m sestamibi (^99mTc-MIBI), employed as an indicator of increased cellular density and metabolic activity, to evaluate Gaucher cell infiltrates in the bone marrow;^99mTc-hexametazime (^99mTc-HMPAO) was also employed, as a pure indicator of lipidic infiltration in the bone marrow. A 67-year-old patient with known type 1 Gaucher's disease presented with a painful left hip and knee and difficulty in gait subsequent to traumatic fracture of the left femoral neck that had required implant of a fixation screw-plaque. Bone scan with^99mTc-methylene diphosphonate revealed reduced uptake at the distal metaphyseal-epiphyseal femoral region. In addition, whole-body maps and spot-view acquisitions of the thighs and legs were recorded at both 30 min and 2.5 h after the injection of^99mTc-MIBI: the scintigraphic pattern clearly showed increased uptake at several sites involved by Gaucher deposits in the bone marrow (both knees, with variable intensity in different areas), matching the bone changes detected by conventional x-ray. The target to non-target ratios slowly decreased with time, from an average value of 2.25 in the early scan to an average value of 2 in the delayed scan. The lipid-soluble agent^99mTc-HMPAO exhibited a superimposable scintigraphic pattern of accumulation at the involved sites, though with lower target to non-target ratios (1.27–1.48). The results obtained in this patient suggest a potential role of^99mTc-MIBI in the scintigraphic evaluation of Gaucher's lipid deposits in the bone marrow. If the results are confirmed in other patients, this radiopharmaceutical would offer clear advantages over¹³³Xe because of its wider availability and greater practicality (i.v. administration of^99mTc-MIBI versus inhalation of¹³³Xe, and use of a single gamma camera instead of two as with¹³³Xe).     

Quantification of technetium-99m hexamethylpropylene amine oxime brain uptake in routine clinical practice using calibrated point sources as an external standard: phantom and human studies

Quantitative methods for calculation of regional cerebral blood flow with technetium-99m hexamethylpropylene amine oxime (^99mTc-HMPAO) have been proposed. These methods are very labour intensive and therefore are not useful in routine clinical practice. We describe a simple alternative method, using calibrated point sources as a scaling factor, whereby the tomographic slices are displayed as regional ^99mTc-HMPAO brain uptake per cm³ brain tissue in 10^–6 of the injected lipophilic dose. The method was validated on Jaszczak and Hoffman phantoms using a three-detector system with HR parallel and HR fan-beam collimators. Under the optimal conditions described in this paper, the measured to real activity ratio was 1.00 (SD = 0.06). The reproducibility of the cerebellar uptake in a group of ten normal volunteers and five patients was studied. Intra-individually a mean deviation of 12.6% was observed for the total group. For those persons with a heart rate difference of less than 5 units between the two studies, a mean deviation of 7.2% was obtained. Quantitative ^99mTc-HMPAO brain uptake images can be useful for longitudinal studies, especially for follow-up, activation and pharmacological studies. Correspondence to: A. Dobbeleir     

Assessment of changes in regional cerebral blood flow in patients with major depression using the 99mTc-HMPAO single photon emission tomography method

Regional cerebral blood flow was investigated in 14 patients with major depression diagnosed according to the DSM-III-R criteria (six patients with single and eight patients with recurrent episodes) and in ten healthy volunteers. The mean ages of the patients and the controls were 33.5 ± 2.7 and 31.6 ± 2.6 years, respectively. The severity of the depression was assessed using the 17-item Hamilton Depression Scale (mean: 23.2 ± 1.5). None of the patients was under medication. After administration of 500 MBq technetium-99m hexamethylpropylene amine oxime, a single photon emission tomography study was performed and then transaxial, sagittal and coronal slices were obtained. For the semiquantitative analysis of the data, the ratios of the mean counts/pixel to the whole slice were calculated for 24 regions on three consecutive transaxial slices in the orbitomeatal plane. Additionally, left/right and frontal/occipital ratios were calculated. Both sides of the temporal region had a significantly decreased cerebral blood flow (CBF) when compared to the controls. The left/right ratio of the prefrontal region was also significantly lower in the patients than in the controls. The Hamilton score had a negative correlation with blood flow in the anterofrontal and left prefrontal regions. According to our results, regional CBF seems to be decreased in the left prefrontal and in both temporal regions in major depression. The severity of depression is correlated with the reduction in CBF in the regions of the anterofrontal and left prefrontal cortex.